Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0005525 GTP binding	IBA GO_REF:0000033	ACCEPT	Summary: FtsZ is a well-established GTP-binding protein. The UniProt record documents multiple GTP binding residues with experimental evidence from crystal structures. GTP binding is essential for FtsZ polymerization and function. Reason: GTP binding is a core molecular function of FtsZ. The UniProt entry states "Binds GTP and shows GTPase activity" and documents specific GTP-binding residues determined by X-ray crystallography. The deep research review confirms that "GTP binding and hydrolysis control filament assembly dynamics, subunit turnover, and ring remodeling" (ftsZ-deep-research-falcon.md). Supporting Evidence: UniProt:P17865 Binds GTP and shows GTPase activity file:BACSU/ftsZ/ftsZ-deep-research-falcon.md GTP binding and hydrolysis control filament assembly dynamics, subunit turnover, and ring remodeling
GO:0005737 cytoplasm	IBA GO_REF:0000033	ACCEPT	Summary: FtsZ localizes to the cytoplasm where it assembles at the inner surface of the cytoplasmic membrane at midcell. The UniProt record confirms cytoplasmic localization. Reason: Cytoplasm is the appropriate cellular component annotation. FtsZ is a soluble cytoplasmic protein that assembles at the membrane-proximal midcell region. UniProt explicitly states FtsZ assembles at midcell at the inner surface of the cytoplasmic membrane. Supporting Evidence: UniProt:P17865 Note=Assembles at midcell at the inner surface of the cytoplasmic membrane
GO:0051301 cell division	IBA GO_REF:0000033	ACCEPT	Summary: FtsZ is essential for cell division in B. subtilis, forming the Z-ring that scaffolds the divisome. This is the canonical and most fundamental biological process for FtsZ. Reason: Cell division is the core biological process for FtsZ. The UniProt FUNCTION states FtsZ is an essential cell division protein. The deep research confirms FtsZ as a conserved tubulin-like GTPase that scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis (ftsZ-deep-research-falcon.md). Supporting Evidence: UniProt:P17865 Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site file:BACSU/ftsZ/ftsZ-deep-research-falcon.md FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis
GO:0003924 GTPase activity	IBA GO_REF:0000033	ACCEPT	Summary: FtsZ exhibits intrinsic GTPase activity that is essential for its function. GTP hydrolysis drives protofilament dynamics and treadmilling. This activity is directly demonstrated biochemically. Reason: GTPase activity is a core molecular function of FtsZ. UniProt states FtsZ binds GTP and shows GTPase activity. Multiple publications demonstrate this activity, and it is critical for FtsZ protofilament dynamics. The deep research notes that GTP hydrolysis is required for polymerization dynamics and filament turnover. Supporting Evidence: UniProt:P17865 Binds GTP and shows GTPase activity file:BACSU/ftsZ/ftsZ-deep-research-falcon.md GTP hydrolysis is required for polymerization dynamics and filament turnover
GO:0032153 cell division site	IBA GO_REF:0000033	ACCEPT	Summary: FtsZ assembles at the cell division site (midcell) to form the Z-ring. This is the primary subcellular localization for its function in cytokinesis. Reason: The cell division site is the precise localization where FtsZ carries out its function. UniProt states FtsZ assembles at midcell. The deep research confirms the Z-ring forms at midcell adjacent to the inner membrane. Supporting Evidence: UniProt:P17865 Note=Assembles at midcell at the inner surface of the cytoplasmic membrane file:BACSU/ftsZ/ftsZ-deep-research-falcon.md The Z-ring forms at midcell adjacent to the inner membrane
GO:0000166 nucleotide binding	IEA GO_REF:0000043	ACCEPT	Summary: FtsZ binds GTP specifically. The parent term nucleotide binding is technically correct but less informative than the more specific GTP binding annotation. Reason: While nucleotide binding is correct, it is redundant with the more specific GO:0005525 (GTP binding) annotation. However, as an IEA annotation from keyword mapping, it is acceptable to retain alongside the more specific IBA annotation for GTP binding. Supporting Evidence: UniProt:P17865 Binds GTP and shows GTPase activity
GO:0000917 division septum assembly	IEA GO_REF:0000043	ACCEPT	Summary: FtsZ is essential for division septum assembly as the Z-ring recruits the machinery for septal wall synthesis. This is a core biological process for FtsZ. Reason: Division septum assembly accurately describes a key biological process involving FtsZ. The Z-ring scaffolds recruitment of late division proteins that catalyze septal peptidoglycan synthesis. UniProt function states the Z-ring serves to recruit other cell division proteins to the septum. Supporting Evidence: UniProt:P17865 One of the functions of the FtsZ ring is to recruit other cell division proteins to the septum to produce a new cell wall between the dividing cells
GO:0003924 GTPase activity	IEA GO_REF:0000120	ACCEPT	Summary: Duplicate annotation for GTPase activity from automated methods. The IBA annotation provides equivalent support. Reason: This is a duplicate of the IBA annotation for GTPase activity. Both are correct and represent independent evidence supporting the same molecular function. It is acceptable to have multiple annotations with different evidence codes for well-established functions. Supporting Evidence: UniProt:P17865 Binds GTP and shows GTPase activity
GO:0005525 GTP binding	IEA GO_REF:0000120	ACCEPT	Summary: Duplicate annotation for GTP binding from combined automated methods. Consistent with the IBA annotation. Reason: This IEA annotation for GTP binding is a duplicate of the IBA annotation but derived from different automated methods. Both correctly annotate the same molecular function with structural evidence. Supporting Evidence: UniProt:P17865 Binds GTP and shows GTPase activity
GO:0005737 cytoplasm	IEA GO_REF:0000120	ACCEPT	Summary: Duplicate annotation for cytoplasm localization from automated methods. Reason: This IEA annotation for cytoplasm is a duplicate of the IBA annotation but derived from different automated methods. Both correctly annotate the same cellular component. Supporting Evidence: UniProt:P17865 Note=Assembles at midcell at the inner surface of the cytoplasmic membrane
GO:0030428 cell septum	IEA GO_REF:0000117	ACCEPT	Summary: FtsZ localizes to the cell septum where it forms the Z-ring that scaffolds septum formation. This is an appropriate cellular component annotation. Reason: Cell septum is an appropriate localization annotation for FtsZ, which assembles at the septum site. The deep research confirms FtsZ scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis. Supporting Evidence: UniProt:P17865 Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site file:BACSU/ftsZ/ftsZ-deep-research-falcon.md FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis
GO:0032153 cell division site	IEA GO_REF:0000104	ACCEPT	Summary: Duplicate annotation for cell division site from automated transfer methods. Reason: This IEA annotation duplicates the IBA annotation for cell division site. Both are correct and consistent with the known localization of FtsZ at midcell. Supporting Evidence: UniProt:P17865 Note=Assembles at midcell at the inner surface of the cytoplasmic membrane
GO:0043093 FtsZ-dependent cytokinesis	IEA GO_REF:0000104	ACCEPT	Summary: This term directly references FtsZ and describes the cytokinesis process that depends on FtsZ function. This is the most specific biological process term for FtsZ. Reason: FtsZ-dependent cytokinesis is the most appropriate and specific biological process annotation for FtsZ itself. FtsZ is essential for this process and defines the pathway. The deep research confirms FtsZ's essential role in bacterial cytokinesis. Supporting Evidence: UniProt:P17865 Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site file:BACSU/ftsZ/ftsZ-deep-research-falcon.md FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis
GO:0051258 protein polymerization	IEA GO_REF:0000104	ACCEPT	Summary: FtsZ self-polymerizes into protofilaments in a GTP-dependent manner. This is a core aspect of FtsZ function. Reason: Protein polymerization accurately describes FtsZ's ability to self-assemble into protofilaments. UniProt states FtsZ polymerizes to form a dynamic ring structure in a GTP-dependent manner. The deep research confirms FtsZ monomers bind GTP and assemble into polar protofilaments. Supporting Evidence: UniProt:P17865 Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity) file:BACSU/ftsZ/ftsZ-deep-research-falcon.md FtsZ monomers bind GTP and assemble into polar protofilaments
GO:0051301 cell division	IEA GO_REF:0000120	ACCEPT	Summary: Duplicate annotation for cell division from combined automated methods. Reason: This IEA annotation for cell division duplicates the IBA annotation. Both are correct and well-supported by the essential role of FtsZ in bacterial cell division. Supporting Evidence: UniProt:P17865 Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site
GO:0090529 cell septum assembly	IEA GO_REF:0000104	ACCEPT	Summary: FtsZ is essential for cell septum assembly as the Z-ring initiates and scaffolds the septation process. This is a specific biological process term. Reason: Cell septum assembly is an appropriate biological process annotation for FtsZ. The Z-ring formed by FtsZ recruits the divisome machinery that carries out septum formation. UniProt states the Z-ring functions to recruit other cell division proteins to the septum to produce a new cell wall between the dividing cells. Supporting Evidence: UniProt:P17865 One of the functions of the FtsZ ring is to recruit other cell division proteins to the septum to produce a new cell wall between the dividing cells
GO:0005515 protein binding	IPI PMID:16796675 A new FtsZ-interacting protein, YlmF, complements the activi...	MODIFY	Summary: This annotation reflects FtsZ interaction with YlmF (SepF) identified by cross-linking and yeast two-hybrid. However, "protein binding" is too general for this well-characterized interaction. Reason: While the interaction is valid, "protein binding" is uninformative. FtsZ interacts with YlmF/SepF, which functions as a membrane anchor and filament bundler for FtsZ. The abstract states YlmF has an overlapping function with FtsA in stimulating the formation of Z rings. A more specific term reflecting FtsZ-anchor interaction would be appropriate, but since GO lacks such a term, the annotation could be retained as evidence of FtsZ's interaction network. Proposed replacements: identical protein binding Supporting Evidence: PMID:16796675 Analysis of the results identified YlmF as a new component of the FtsZ complex
GO:0005515 protein binding	IPI PMID:17662947 A metabolic sensor governing cell size in bacteria.	MODIFY	Summary: This annotation reflects FtsZ interaction with UgtP, a metabolic sensor that inhibits FtsZ assembly. The term "protein binding" is too general. Reason: The interaction with UgtP is well-documented as a regulatory mechanism linking nutrient availability to cell division. The abstract states UgtP localizes to the division site in a nutrient-dependent manner and inhibits assembly of the tubulin-like cell division protein FtsZ. However, "protein binding" is too vague for this important regulatory interaction. UniProt documents the interaction. Proposed replacements: identical protein binding Supporting Evidence: PMID:17662947 UgtP, which localizes to the division site in a nutrient-dependent manner and inhibits assembly of the tubulin-like cell division protein FtsZ
GO:0005515 protein binding	IPI PMID:21224850 Large ring polymers align FtsZ polymers for normal septum fo...	MODIFY	Summary: This annotation reflects FtsZ interaction with SepF, which forms large ring polymers that bundle and align FtsZ filaments. "Protein binding" is too general. Reason: The interaction between FtsZ and SepF is well-characterized. The publication shows SepF is able to bundle FtsZ protofilaments into strikingly long and regular tubular structures. While the interaction is real, "protein binding" fails to capture the functional significance. Proposed replacements: identical protein binding Supporting Evidence: PMID:21224850 able to bundle FtsZ protofilaments into strikingly long and regular tubular structures reminiscent of eukaryotic microtubules
GO:0005515 protein binding	IPI PMID:21630458 An expanded protein-protein interaction network in Bacillus ...	MARK AS OVER ANNOTATED	Summary: This annotation comes from a large-scale yeast two-hybrid study in B. subtilis. "Protein binding" is too general for functional annotation. Reason: This annotation derives from a high-throughput protein-protein interaction network study that identified FtsZ interactions among many others. While interactions are real, "protein binding" from high-throughput studies adds little functional information. Supporting Evidence: PMID:21630458 We have generated a protein-protein interaction network in Bacillus subtilis focused on several essential cellular processes such as cell division, cell responses to various stresses, the bacterial cytoskeleton, DNA replication and chromosome maintenance by careful application of the yeast two-hybrid approach
GO:0042802 identical protein binding	IPI PMID:16796675 A new FtsZ-interacting protein, YlmF, complements the activi...	ACCEPT	Summary: FtsZ forms homodimers and homopolymers. This annotation likely reflects FtsZ self-interaction detected in the cross-linking/mass spec study of FtsZ complexes. Reason: FtsZ self-polymerization is essential for Z-ring formation. UniProt states FtsZ is a homodimer that polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner. The IntAct database records FtsZ-FtsZ interactions with 6 experiments. Supporting Evidence: UniProt:P17865 Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)
GO:0042802 identical protein binding	IPI PMID:17662947 A metabolic sensor governing cell size in bacteria.	ACCEPT	Summary: This annotation may reflect FtsZ self-interaction detected in the context of studying UgtP regulation of FtsZ assembly. Reason: FtsZ homo-oligomerization is well-established and central to its function. The study examining UgtP inhibition of FtsZ assembly would have detected FtsZ self-interactions as part of the polymerization assays. Supporting Evidence: UniProt:P17865 Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)
GO:0042802 identical protein binding	IPI PMID:21224850 Large ring polymers align FtsZ polymers for normal septum fo...	ACCEPT	Summary: FtsZ self-polymerization is essential for forming the protofilaments that are bundled by SepF. This study directly examined FtsZ polymerization. Reason: The publication explicitly studied FtsZ polymerization and its bundling by SepF. The methods describe FtsZ polymerization and GTPase assays with FtsZ. Self-interaction is a prerequisite for the bundled structures observed. Supporting Evidence: PMID:21224850 B. subtilis FtsZ was purified as described previously (Wang and Lutkenhaus, 1993; Scheffers, 2008)
GO:0042802 identical protein binding	IPI PMID:21630458 An expanded protein-protein interaction network in Bacillus ...	ACCEPT	Summary: FtsZ self-interaction detected in the high-throughput two-hybrid network study. Reason: FtsZ homo-oligomerization is a well-established core function. Detection in the two-hybrid study is consistent with established biochemistry. IntAct records 6 experiments supporting FtsZ-FtsZ interaction. Supporting Evidence: UniProt:P17865 Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)
GO:0051301 cell division	EXP PMID:22298780 Extreme C terminus of bacterial cytoskeletal protein FtsZ pl...	ACCEPT	Summary: This study examined the role of the FtsZ C-terminal variable region in lateral interactions between protofilaments and Z-ring integrity, directly demonstrating FtsZ's role in cell division. Reason: The publication provides direct experimental evidence for FtsZ's role in cell division in B. subtilis. It states bacterial cell division typically requires assembly of the cytoskeletal protein FtsZ into a ring at the nascent division site and shows that C-terminal mutations cause a low frequency of FtsZ ring formation and a high degree of filamentation. Supporting Evidence: PMID:22298780 Bacterial cell division typically requires assembly of the cytoskeletal protein FtsZ into a ring (Z-ring) at the nascent division site that serves as a foundation for assembly of the division apparatus
GO:0003924 GTPase activity	IDA PMID:23577149 Genetic and biochemical characterization of the MinC-FtsZ in...	ACCEPT	Summary: This study directly assayed FtsZ GTPase activity and critical concentration as part of characterizing MinC-FtsZ interactions. The GTPase activity measurements provide direct experimental evidence. Reason: The publication directly measured GTPase activity of wild-type and mutant FtsZ. The methods describe GTPase Activity and Critical Concentration assays, and results include GTPase activity measurements of FtsZ mutants. This provides direct biochemical evidence (IDA) for the GTPase molecular function. Supporting Evidence: PMID:23577149 GTPase activity and Cc of FtsZ mutants
GO:0051301 cell division	IMP PMID:18573169 A sensor histidine kinase co-ordinates cell wall architectur...	ACCEPT	Summary: This study used FtsZ depletion to examine YycG kinase function, providing mutant phenotype evidence for FtsZ's role in cell division. Reason: The abstract describes using FtsZ-depleted, septum-less cells to study YycG kinase activity, indicating that FtsZ depletion prevents septum formation. This mutant phenotype evidence (IMP) supports the cell division annotation. Supporting Evidence: PMID:18573169 RT-PCR quantification of YycF approximately PO(4)-regulated gene transcription, in wild type and FtsZ-depleted, septum-less cells, indicated that YycG kinase activity on YycF is dependent on YycG localization to a division septum
GO:0030428 cell septum	IDA PMID:18573169 A sensor histidine kinase co-ordinates cell wall architectur...	ACCEPT	Summary: The study examining YycG localization demonstrates that the septum forms at the FtsZ ring location, supporting FtsZ localization at the cell septum. Reason: The publication shows that YycG sensor histidine kinase is a component of the division septum and that its activity depends on localization to the septum where FtsZ forms the Z-ring. The study of septum-less cells in FtsZ-depleted conditions confirms FtsZ's role at the septum. Supporting Evidence: PMID:18573169 YycG sensor histidine kinase is a component of the division septum in growing cells

Core Functions

FtsZ is a tubulin-like GTPase whose enzymatic activity drives protofilament dynamics through GTP hydrolysis. This is the primary molecular function.

Molecular Function:

GTPase activity

Directly Involved In:

FtsZ-dependent cytokinesis

Cellular Locations:

cell division site

FtsZ homo-oligomerization is essential for protofilament formation and Z-ring assembly. This self-polymerization underlies all downstream functions.

Molecular Function:

identical protein binding

Directly Involved In:

protein polymerization

Cellular Locations:

cell division site

References

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000043

Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping

GO_REF:0000104

Electronic Gene Ontology annotations created by transferring manual GO annotations between related proteins based on shared sequence features

GO_REF:0000117

Electronic Gene Ontology annotations created by ARBA machine learning models

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

PMID:16796675

A new FtsZ-interacting protein, YlmF, complements the activity of FtsA during progression of cell division in Bacillus subtilis.

YlmF (SepF) identified as FtsZ-interacting protein

"Analysis of the results identified YlmF as a new component of the FtsZ complex"
YlmF has overlapping function with FtsA in Z-ring formation

"YlmF has an overlapping function with FtsA in stimulating the formation of Z rings in B. subtilis"

PMID:17662947

A metabolic sensor governing cell size in bacteria.

UgtP identified as metabolic sensor that inhibits FtsZ assembly

"UgtP, which localizes to the division site in a nutrient-dependent manner and inhibits assembly of the tubulin-like cell division protein FtsZ"
Links nutrient availability to cell division control

"Nutrient availability is one of the strongest determinants of cell size"

PMID:18573169

A sensor histidine kinase co-ordinates cell wall architecture with cell division in Bacillus subtilis.

YycG kinase localizes to division septum

"YycG sensor histidine kinase is a component of the division septum in growing cells"
FtsZ depletion produces septum-less cells

"wild type and FtsZ-depleted, septum-less cells"

PMID:21224850

Large ring polymers align FtsZ polymers for normal septum formation.

SepF forms large ring polymers that bundle FtsZ protofilaments

"able to bundle FtsZ protofilaments into strikingly long and regular tubular structures reminiscent of eukaryotic microtubules"
SepF rings required for regular arrangement of FtsZ filaments

"We propose that SepF rings are required for the regular arrangement of FtsZ filaments"

PMID:21630458

An expanded protein-protein interaction network in Bacillus subtilis reveals a group of hubs.

High-throughput protein-protein interaction network in B. subtilis

"We have generated a protein-protein interaction network in Bacillus subtilis focused on several essential cellular processes such as cell division, cell responses to various stresses, the bacterial cytoskeleton, DNA replication and chromosome maintenance by careful application of the yeast two-hybrid approach"
FtsZ identified as hub protein in cell division pathway

"A striking feature of the network is a group of highly connected hubs (GoH) linking many different cellular processes"

PMID:22298780

Extreme C terminus of bacterial cytoskeletal protein FtsZ plays fundamental role in assembly independent of modulatory proteins.

C-terminal variable region mediates lateral interactions between FtsZ polymers

"residues at the C terminus of Bacillus subtilis FtsZ (C-terminal variable region (CTV)) are both necessary and sufficient for stimulating lateral interactions in vitro in the absence of modulatory proteins"
CTV mutations cause filamentation and reduced Z-ring formation

"B. subtilis cells expressing the B. subtilis FtsZ chimera had a low frequency of FtsZ ring formation and a high degree of filamentation relative to wild-type cells"

PMID:23577149

Genetic and biochemical characterization of the MinC-FtsZ interaction in Bacillus subtilis.

MinC inhibits FtsZ polymerization

"The best studied of these regulators is MinC, an inhibitor of FtsZ polymerization that plays a crucial role in the spatial control of Z ring formation"
Identified MinC binding site on FtsZ

"determine the binding site for MinC on B. subtilis FtsZ"
GTPase activity measured for FtsZ mutants

"GTPase activity and Cc of FtsZ mutants"

UniProt:P17865

UniProt entry for B. subtilis FtsZ

Essential cell division protein forming Z-ring

"Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site"
GTP binding and GTPase activity

"Binds GTP and shows GTPase activity"
Interacts with FtsA, SepF, EzrA, ZapA, UgtP

"Interacts directly with several other division proteins (By similarity). Interacts with FtsA"
Regulated by MciZ during sporulation

"During sporulation, is negatively regulated by MciZ, which binds to FtsZ and inhibits its polymerization and the formation of the Z ring"
Crystal structure solved to 1.7 angstroms

"PDB; 2VXY; X-ray; 1.70 A; A=1-382"

file:BACSU/ftsZ/ftsZ-deep-research-falcon.md

Deep research review of FtsZ in B. subtilis

FtsZ is a conserved tubulin-like GTPase essential for bacterial cell division

"FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis"
GTP binding and hydrolysis control filament dynamics

"GTP binding and hydrolysis control filament assembly dynamics, subunit turnover, and ring remodeling"
Multiple membrane tethers anchor the Z-ring

"FtsZ lacks an intrinsic membrane anchor and is tethered via membrane-associated partners, notably FtsA and SepF, with EzrA also acting as a multifunctional tether/regulator in B. subtilis"

Suggested Experiments

Experiment: Single-molecule imaging of FtsZ dynamics in strains lacking individual or combinations of regulatory proteins (EzrA, ZapA, SepF) to determine their specific contributions to ring condensation. Recent work shows Z-ring condensation is essential but the relative roles of individual ZBPs are not fully resolved.

📚 Additional Documentation

Deep Research Bioreason

(ftsZ-deep-research-bioreason.md)

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Exported on March 22, 2026 at 02:25 AM

Organism: Bacillus subtilis

Sequence:

MLEFETNIDGLASIKVIGVGGGGNNAVNRMIENEVQGVEYIAVNTDAQALNLSKAEVKMQIGAKLTRGLGAGANPEVGKKAAEESKEQIEEALKGADMVFVTAGMGGGTGTGAAPVIAQIAKDLGALTVGVVTRPFTFEGRKRQLQAAGGISAMKEAVDTLIVIPNDRILEIVDKNTPMLEAFREADNVLRQGVQGISDLIATPGLINLDFADVKTIMSNKGSALMGIGIATGENRAAEAAKKAISSPLLEAAIDGAQGVLMNITGGTNLSLYEVQEAADIVASASDQDVNMIFGSVINENLKDEIVVTVIATGFIEQEKDVTKPQRPSLNQSIKTHNQSVPKREPKREEPQQQNTVSRHTSQPADDTLDIPTFLRNRNKRG

Thinking Trace

I begin with the InterPro architecture. The N-terminal half is defined by IPR036525 (Tubulin/FtsZ, GTPase domain superfamily, residues 6–220) and IPR003008 (Tubulin/FtsZ, GTPase domain, residues 13–233), together with the embedded IPR020805 conserved site (Cell division protein FtsZ, residues 44–118). This constellation establishes a P-loop NTPase core that binds and hydrolyzes GTP, the hallmark of the tubulin/FtsZ lineage. The full-length identity is reinforced by two family-level signatures, IPR000158 (Cell division protein FtsZ family, residues 9–358) and IPR045061 (Tubulin-like protein FtsZ/CetZ family, residues 12–335), which anchor the protein within bacterial and plastid tubulin homologs that polymerize into cytomotive filaments. The C-terminal half carries IPR008280 (Tubulin/FtsZ, C-terminal homologous superfamily, residues 204–315), IPR018316 (Tubulin/FtsZ, 2-layer sandwich domain, residues 207–324), IPR037103 (Tubulin/FtsZ-like, C-terminal domain, residues 221–330), and the specific IPR024757 (Cell division protein FtsZ, C-terminal domain, residues 222–315). This C-terminal module forms the β-sandwich that mediates longitudinal and lateral filament contacts and presents an interaction hotspot that recruits assembly partners. The ordered layout—an N-terminal GTPase engine followed by a C-terminal filament/docking module—causally dictates a GTP-driven polymer that self-associates and scaffolds downstream cell division machinery.

From this architecture, the molecular function follows directly. The paired GTPase-domain signatures (IPR036525 and IPR003008) and the conserved-site block (IPR020805) specify GO:0005525 GTP binding and GO:0003924 GTPase activity. GTP binding and hydrolysis regulate filament assembly/disassembly cycles that switch the polymer between active and disassembly-prone states, tuning filament treadmilling.

These filament dynamics seed and organize the cytokinetic apparatus. The C-terminal docking platform (IPR008280/IPR018316/IPR037103/IPR024757) recruits and stabilizes early cell-division components, translating filament curvature and turnover into a supramolecular scaffold. This establishes the causal route into biological processes of membrane constriction and septum formation: cytokinesis (GO:0000910), cell division (GO:0051301), and cell wall biogenesis that builds the cross wall.

Cellular localization is dictated by function and assembly logic. A soluble, polymerizing GTPase without transmembrane segments operates in the cytoplasm and transiently associates with the cytoskeleton and membrane-proximal zones. Thus the cellular component is the cytoplasm (GO:0005737), with assembly into cytoplasmic cytoskeletal structures that align near the division site.

Mechanistically, I hypothesize that the N-terminal GTPase domain nucleates protofilaments whose treadmilling patterns the C-terminal β-sandwich into a circumferential ring. This ring provides a landing pad for early cell division factors and membrane-remodeling modules. Likely interaction partners include membrane tethers and adaptors that bridge to the invagination site, as well as early septal biogenesis factors that read FtsZ filament curvature to position peptidoglycan synthases. In Bacillus subtilis, this implies transient assemblies with membrane-associated tethers and early septal organizers that channel FtsZ-generated curvature into the constriction machinery.

Functional Summary

A cytoplasmic, filament-forming GTPase that builds the central scaffold for bacterial cytokinesis. Its N-terminal nucleotide-binding engine drives polymerization and turnover, while its C-terminal β-sandwich mediates filament contacts and recruits early division factors. By assembling into a circumferential ring at the future division site, it orchestrates constriction and coordinates synthesis of the new cross wall through regulated filament treadmilling and partner recruitment.

UniProt Summary

Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site. The regulation of the ring assembly controls cell division and cell wall synthesis.

InterPro Domains

Tubulin/FtsZ, GTPase domain superfamily (IPR036525, homologous_superfamily) — residues 6-220
Cell division protein FtsZ (IPR000158, family) — residues 9-358
Tubulin-like protein FtsZ/CetZ (IPR045061, family) — residues 12-335
Tubulin/FtsZ, GTPase domain (IPR003008, domain) — residues 13-233
Cell division protein FtsZ, conserved site (IPR020805, conserved_site) — residues 44-118
Tubulin/FtsZ, C-terminal (IPR008280, homologous_superfamily) — residues 204-315
Tubulin/FtsZ, 2-layer sandwich domain (IPR018316, domain) — residues 207-324
Tubulin/FtsZ-like, C-terminal domain (IPR037103, homologous_superfamily) — residues 221-330
Cell division protein FtsZ, C-terminal (IPR024757, domain) — residues 222-315

GO Terms

Molecular Function: molecular_function (GO:0003674), binding (GO:0005488), catalytic activity (GO:0003824), hydrolase activity (GO:0016787), protein binding (GO:0005515), identical protein binding (GO:0042802), hydrolase activity, acting on acid anhydrides (GO:0016817), hydrolase activity, acting on acid anhydrides, in phosphorus-containing anhydrides (GO:0016818), pyrophosphatase activity (GO:0016462), ribonucleoside triphosphate phosphatase activity (GO:0017111), GTPase activity (GO:0003924)

Biological Process: biological_process (GO:0008150), cellular process (GO:0009987), cell division (GO:0051301)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), cell septum (GO:0030428)

Generated by BioReason

Deep Research Bioreason Rl

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Exported on March 22, 2026 at 02:25 AM

Organism: Bacillus subtilis

Sequence:

MLEFETNIDGLASIKVIGVGGGGNNAVNRMIENEVQGVEYIAVNTDAQALNLSKAEVKMQIGAKLTRGLGAGANPEVGKKAAEESKEQIEEALKGADMVFVTAGMGGGTGTGAAPVIAQIAKDLGALTVGVVTRPFTFEGRKRQLQAAGGISAMKEAVDTLIVIPNDRILEIVDKNTPMLEAFREADNVLRQGVQGISDLIATPGLINLDFADVKTIMSNKGSALMGIGIATGENRAAEAAKKAISSPLLEAAIDGAQGVLMNITGGTNLSLYEVQEAADIVASASDQDVNMIFGSVINENLKDEIVVTVIATGFIEQEKDVTKPQRPSLNQSIKTHNQSVPKREPKREEPQQQNTVSRHTSQPADDTLDIPTFLRNRNKRG

Thinking Trace

Functional Summary

UniProt Summary

Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site. The regulation of the ring assembly controls cell division and cell wall synthesis.

InterPro Domains

Tubulin/FtsZ, GTPase domain superfamily (IPR036525, homologous_superfamily) — residues 6-220
Cell division protein FtsZ (IPR000158, family) — residues 9-358
Tubulin-like protein FtsZ/CetZ (IPR045061, family) — residues 12-335
Tubulin/FtsZ, GTPase domain (IPR003008, domain) — residues 13-233
Cell division protein FtsZ, conserved site (IPR020805, conserved_site) — residues 44-118
Tubulin/FtsZ, C-terminal (IPR008280, homologous_superfamily) — residues 204-315
Tubulin/FtsZ, 2-layer sandwich domain (IPR018316, domain) — residues 207-324
Tubulin/FtsZ-like, C-terminal domain (IPR037103, homologous_superfamily) — residues 221-330
Cell division protein FtsZ, C-terminal (IPR024757, domain) — residues 222-315

GO Terms

Biological Process: biological_process (GO:0008150), cellular process (GO:0009987), cell division (GO:0051301)

Cellular Component: cellular_component (GO:0005575), cellular anatomical entity (GO:0110165), cell septum (GO:0030428)

Generated by BioReason

Deep Research Falcon

(ftsZ-deep-research-falcon.md)

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gene_info: Name=ftsZ {ECO:0000255|HAMAP-Rule:MF_00909}; OrderedLocusNames=BSU15290;
organism_full: Bacillus subtilis (strain 168).
protein_family: Belongs to the FtsZ family. {ECO:0000255|HAMAP-
protein_domains: Cell_div_FtsZ. (IPR000158); Cell_div_FtsZ_CS. (IPR020805); FtsZ/CetZ.
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Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P17865
Protein Description: RecName: Full=Cell division protein FtsZ {ECO:0000255|HAMAP-Rule:MF_00909};
Gene Information: Name=ftsZ {ECO:0000255|HAMAP-Rule:MF_00909}; OrderedLocusNames=BSU15290;
Organism (full): Bacillus subtilis (strain 168).
Protein Family: Belongs to the FtsZ family. {ECO:0000255|HAMAP-
Key Domains: Cell_div_FtsZ. (IPR000158); Cell_div_FtsZ_CS. (IPR020805); FtsZ/CetZ. (IPR045061); FtsZ_C. (IPR024757); Tub_FtsZ_C. (IPR008280)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "ftsZ" matches the protein description above
Verify the organism is correct: Bacillus subtilis (strain 168).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'ftsZ' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information

Research Target:

Please provide a comprehensive research report on the gene ftsZ (gene ID: ftsZ, UniProt: P17865) in BACSU.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.

We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.

Output

Question: You are an expert researcher providing comprehensive, well-cited information.

Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies

Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.

Target Gene/Protein Identity (from UniProt):

UniProt Accession: P17865
Protein Description: RecName: Full=Cell division protein FtsZ {ECO:0000255|HAMAP-Rule:MF_00909};
Gene Information: Name=ftsZ {ECO:0000255|HAMAP-Rule:MF_00909}; OrderedLocusNames=BSU15290;
Organism (full): Bacillus subtilis (strain 168).
Protein Family: Belongs to the FtsZ family. {ECO:0000255|HAMAP-
Key Domains: Cell_div_FtsZ. (IPR000158); Cell_div_FtsZ_CS. (IPR020805); FtsZ/CetZ. (IPR045061); FtsZ_C. (IPR024757); Tub_FtsZ_C. (IPR008280)

MANDATORY VERIFICATION STEPS:

Check if the gene symbol "ftsZ" matches the protein description above
Verify the organism is correct: Bacillus subtilis (strain 168).
Check if protein family/domains align with what you find in literature
If you find literature for a DIFFERENT gene with the same or similar symbol, STOP

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Please provide a comprehensive research report on the gene ftsZ (gene ID: ftsZ, UniProt: P17865) in BACSU.

The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.

We are interested in where in or outside the cell the gene product carries out its function.

We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.

Plan and identity verification
We verified the target as Bacillus subtilis (strain 168) cell division protein FtsZ (gene ftsZ; UniProt P17865), a bacterial tubulin homolog belonging to the FtsZ family and containing the canonical FtsZ (Cell_div_FtsZ) domain architecture. The literature cited below aligns with this identity and organism, and describes the same family/domain features and functions (assembly of a midcell Z-ring, GTP-dependent polymerization, membrane anchoring via FtsA/SepF/EzrA, recruitment of the divisome). No conflicting gene symbol usage was found in other organisms for the specific B. subtilis context considered in this report (cameron2024insightsintothe pages 20-22, naha2023anchorsaway pages 8-9, battaje2023modelsversuspathogens pages 19-20).

Comprehensive research report
1) Key concepts and definitions with current understanding
- Definition and primary role: FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis. GTP binding and hydrolysis control filament assembly dynamics, subunit turnover, and ring remodeling (https://doi.org/10.1038/s41579-023-00942-x, Jul 2024; https://doi.org/10.1038/s41564-021-00878-z, Mar 2021) (cameron2024insightsintothe pages 20-22, squyres2021singlemoleculeimagingreveals pages 1-2).
- Localization: The Z-ring forms at midcell adjacent to the inner membrane. FtsZ lacks an intrinsic membrane anchor and is tethered via membrane-associated partners, notably FtsA and SepF, with EzrA also acting as a multifunctional tether/regulator in B. subtilis. Multiple partially redundant tethers optimize Z-ring architecture and divisome assembly (https://doi.org/10.1111/mmi.15067, Apr 2023; https://doi.org/10.1038/s41579-023-00942-x, Jul 2024) (naha2023anchorsaway pages 8-9, cameron2024insightsintothe pages 20-22).
- Interaction network and divisome context: Early division proteins include FtsZ with anchors/tethering/bundling factors (FtsA, SepF, EzrA, ZapA). Late division components include the transmembrane septal synthases (FtsW, Pbp2B) and the DivIB–DivIC–FtsL complex that scaffold/activate peptidoglycan synthesis. Spatial regulators position the Z-ring: the MinC/MinD/MinJ system blocks polar FtsZ assembly; nucleoid occlusion by Noc prevents division over the nucleoid; metabolic cues (e.g., UgtP) link growth status to Z-ring assembly (https://doi.org/10.1101/2024.01.12.575403, Jan 2024; https://doi.org/10.1038/s41579-023-00942-x, Jul 2024) (gulsoy2024divisomeminimizationshows pages 1-4, cameron2024insightsintothe pages 20-22).

2) Recent developments and latest research (prioritizing 2023–2024)
- Multi-anchor mechanisms and EzrA function: Recent review and mechanistic synthesis emphasize overlapping membrane tether systems. In B. subtilis, EzrA acts as a negative regulator of excessive bundling and also serves as a multifunctional Z-ring tether/scaffold that interfaces with FtsZ, FtsA, SepF, and ZapA, and contributes to PG synthase recruitment (https://doi.org/10.1111/mmi.15067, Apr 2023) (naha2023anchorsaway pages 8-9).
- Z-ring condensation as a prerequisite to cytokinesis: Live-cell single-molecule imaging in B. subtilis revealed that Z-binding proteins (ZBPs: EzrA, SepF, ZapA, along with FtsA) transiently bind treadmilling FtsZ subunits to condense filaments into a dense Z-ring, and that this condensation step is essential for successful septation. The divisome comprises a stationary ZBP subcomplex and a directionally moving synthase complex (https://doi.org/10.1038/s41564-021-00878-z, Mar 2021). The 2024 review integrates these findings within broader divisome regulation (https://doi.org/10.1038/s41579-023-00942-x, Jul 2024) (squyres2021singlemoleculeimagingreveals pages 1-2, cameron2024insightsintothe pages 20-22).
- Minimal divisome configurations: A 2024 B. subtilis minimization study indicates that FtsZ together with SepF can suffice to form a functional Z-ring in engineered backgrounds lacking multiple accessory/regulatory proteins; viability was retained albeit with reduced division frequency and with suppressor mutations arising. This underscores redundancy and robustness in the anchoring/condensation network and nominates SepF as a pivotal anchor in minimal systems (https://doi.org/10.1101/2024.01.12.575403, Jan 2024). A 2025 peer-reviewed extension similarly supports FtsZ+SepF sufficiency for ring formation and documents suppressors (https://doi.org/10.1371/journal.pgen.1011567, Jan 2025) (gulsoy2024divisomeminimizationshows pages 1-4, gulsoy2025minimizationofthe pages 2-4).
- Conceptual advances on treadmilling-mediated self-organization: A 2024 theory–experiment study linked filament treadmilling to nematic ordering via dissolution of misaligned filaments, explaining robust ring organization and rapid response to cellular biases in vivo in B. subtilis. This provides a framework for how FtsZ dynamics drive large-scale ring alignment and assembly (https://doi.org/10.1038/s41567-024-02597-8, Aug 2024) (vasquez2024thezringin pages 17-19).

3) Current applications and real-world implementations
- Antibacterial targeting: FtsZ remains a high-value antibacterial target. Comparative analyses of FtsZ across species and reviews of anti-FtsZ chemotypes emphasize species-specific regulation and interaction networks that influence inhibitor action, motivating organism-tailored design and validation strategies (https://doi.org/10.1042/bsr20221664, Feb 2023; https://doi.org/10.1038/s41579-023-00942-x, Jul 2024) (battaje2023modelsversuspathogens pages 19-20, cameron2024insightsintothe pages 20-22).
- Synthetic biology/minimal systems: Divisome minimization in B. subtilis suggests a tractable minimal cytokinesis module (FtsZ+SepF) that can be leveraged to dissect essential mechanics of ring formation, anchor function, and anchoring–synthesis coupling in vivo (https://doi.org/10.1101/2024.01.12.575403, Jan 2024; https://doi.org/10.1371/journal.pgen.1011567, Jan 2025) (gulsoy2024divisomeminimizationshows pages 1-4, gulsoy2025minimizationofthe pages 2-4).
- Advanced imaging: B. subtilis divisome studies increasingly use live-cell single-molecule and super-resolution imaging to quantify molecular lifetimes, ring condensation dynamics, and modular divisome movements, providing platforms to evaluate on-target effects of inhibitors and perturbations (https://doi.org/10.1038/s41564-021-00878-z, Mar 2021; https://doi.org/10.1038/s41579-023-00942-x, Jul 2024) (squyres2021singlemoleculeimagingreveals pages 1-2, cameron2024insightsintothe pages 20-22).

4) Expert opinions and analysis from authoritative sources
- The 2024 Nature Reviews Microbiology synthesis (Cameron & Margolin) frames the divisome as a modular, temporally controlled machine, with FtsZ’s Z-ring initiating assembly, multiple anchors/tethers (FtsA/SepF/EzrA) providing redundancy and architectural control, and late synthase complexes executing septal wall synthesis. It highlights spatial regulators (Min and Noc systems) and developmental regulators (e.g., MciZ) that tune FtsZ polymerization/positioning (https://doi.org/10.1038/s41579-023-00942-x, Jul 2024) (cameron2024insightsintothe pages 20-22).
- The 2023 Molecular Microbiology review on anchors (Naha, Haeusser & Margolin) emphasizes the prevalent use of multiple overlapping membrane tethers (FtsA, SepF, EzrA) across bacteria, arguing these not only attach FtsZ to membranes but also organize higher-order structures to optimize division activity. In B. subtilis, EzrA is a central, multifunctional tether with dual regulatory roles (https://doi.org/10.1111/mmi.15067, Apr 2023) (naha2023anchorsaway pages 8-9).
- The 2024 minimization study (bioRxiv) and 2025 peer-reviewed follow-up argue that SepF is sufficient with FtsZ to form an active Z-ring in engineered B. subtilis, consistent with deep evolutionary conservation of SepF as an FtsZ anchor, and propose new links between cell physiology (BraB transporter) and division (https://doi.org/10.1101/2024.01.12.575403, Jan 2024; https://doi.org/10.1371/journal.pgen.1011567, Jan 2025) (gulsoy2024divisomeminimizationshows pages 1-4, gulsoy2025minimizationofthe pages 2-4).

5) Relevant statistics and data from recent studies
- Single-molecule lifetimes and condensation: In B. subtilis cells, live-cell single-molecule imaging measured a mean FtsZ subunit lifetime of approximately 8.1 s (half-life ∼5.6 s) at the Z-ring, consistent with a dynamic steady state where ZBPs condense filaments and stationary FtsZ-binding subcomplexes coexist with moving synthase complexes (Nature Microbiology, Mar 2021; https://doi.org/10.1038/s41564-021-00878-z) (squyres2021singlemoleculeimagingreveals pages 1-2).
- Qualitative dependencies: Across systems, synthase complex movement and septal constriction can be tightly or loosely coupled to FtsZ treadmilling; authoritative syntheses emphasize species- and context-specific coupling and underscore Z-ring condensation as a critical, separable step prior to robust septation (https://doi.org/10.1038/s41579-023-00942-x, Jul 2024; https://doi.org/10.1038/s41564-021-00878-z, Mar 2021) (cameron2024insightsintothe pages 20-22, squyres2021singlemoleculeimagingreveals pages 1-2).

Mechanistic synthesis for Bacillus subtilis FtsZ (P17865)
- Biochemical mechanism: FtsZ monomers bind GTP and assemble into polar protofilaments. GTP hydrolysis promotes subunit turnover, enabling treadmilling and remodeling. In B. subtilis, ZBPs (ZapA, SepF, EzrA) and FtsA transiently bind FtsZ to bundle/condense filaments into a functional Z-ring, which is essential for division. The Z-ring then recruits late divisome proteins (FtsW, Pbp2B, DivIB/DivIC/FtsL) that catalyze and regulate septal peptidoglycan synthesis (https://doi.org/10.1038/s41564-021-00878-z; https://doi.org/10.1101/2024.01.12.575403; https://doi.org/10.1038/s41579-023-00942-x) (squyres2021singlemoleculeimagingreveals pages 1-2, gulsoy2024divisomeminimizationshows pages 1-4, cameron2024insightsintothe pages 20-22).
- Spatial control and anchoring: The Z-ring’s proper placement depends on MinCD/MinJ (polar inhibition) and Noc (nucleoid occlusion). Anchoring to the membrane is achieved via FtsA and SepF, with EzrA acting as a multifunctional tether and regulator of lateral bundling. Overlapping anchoring pathways confer robustness; EzrA’s scaffolding and inhibitory effects fine-tune ring architecture and dynamics (https://doi.org/10.1111/mmi.15067; https://doi.org/10.1038/s41579-023-00942-x; https://doi.org/10.1101/2024.01.12.575403) (naha2023anchorsaway pages 8-9, cameron2024insightsintothe pages 20-22, gulsoy2024divisomeminimizationshows pages 1-4).
- Pathway context and coupling to cell wall synthesis: The divisome comprises at least two dynamic modules—stationary ZBPs associated with treadmilling FtsZ and a directionally moving synthase complex (e.g., Pbp2B, FtsW with DivIB/DivIC/FtsL). In B. subtilis, Z-ring condensation by ZBPs is a decisive prerequisite; the precise quantitative coupling between FtsZ treadmilling and synthase movement may vary, but recruitment and spatial organization by FtsZ remain central (https://doi.org/10.1038/s41564-021-00878-z; https://doi.org/10.1038/s41579-023-00942-x) (squyres2021singlemoleculeimagingreveals pages 1-2, cameron2024insightsintothe pages 20-22).
- Implications for antibiotics: As an essential, well-conserved organizer of bacterial cytokinesis, FtsZ is a validated antibacterial target. However, species-specific anchor networks, regulators, and coupling to synthase motion shape inhibitor responses. Reviews highlight the need to tailor inhibitors to organismal FtsZ dynamics and anchoring environments; the advent of in vivo imaging and minimal divisome systems in B. subtilis provides rigorous, mechanistically grounded assays for on-target validation (https://doi.org/10.1042/bsr20221664; https://doi.org/10.1038/s41579-023-00942-x; https://doi.org/10.1101/2024.01.12.575403) (battaje2023modelsversuspathogens pages 19-20, cameron2024insightsintothe pages 20-22, gulsoy2024divisomeminimizationshows pages 1-4).

Embedded summary artifact
| Aspect | Summary (2–3 sentences) | Quantitative/Notes | Key Partners/Regulators | Best Sources |
|---|---|---:|---|---|
| Identity & domains | Conserved tubulin homolog FtsZ that polymerizes into GTP-dependent protofilaments and forms the division scaffold in bacteria. Sequence/structural conservation across model organisms underpins functional inference for B. subtilis FtsZ. | Canonical FtsZ domain architecture (Cell_div_FtsZ family) inferred across bacteria. | — | (battaje2023modelsversuspathogens pages 19-20, cameron2024insightsintothe pages 20-22) |
| Cellular localization | Assembles at midcell into a membrane-associated Z‑ring; membrane tethering is mediated by multiple anchors (FtsA, SepF and others), which localize FtsZ filaments close to the membrane. | Cryo-EM in model systems places FtsZ protofilaments ~15–16 nm from the membrane, implying roles for anchors in bridging to membrane and late divisome. | FtsA, SepF, EzrA (anchors/tethers) | (cameron2024insightsintothe pages 20-22, naha2023anchorsaway pages 8-9, gulsoy2025minimizationofthe pages 2-4) |
| Primary function & mechanism | Acts as a GTPase whose polymerization into head‑to‑tail protofilaments nucleates the Z‑ring and scaffolds recruitment of septal peptidoglycan (PG) synthesis machinery. FtsZ dynamics (assembly/disassembly coupled to GTP hydrolysis) underlie ring remodeling. | GTP hydrolysis is required for polymerization dynamics and filament turnover. | Recruits late PG synthases via membrane‑anchoring/adaptor system. | (squyres2021singlemoleculeimagingreveals pages 1-2, cameron2024insightsintothe pages 20-22, gulsoy2024divisomeminimizationshows pages 1-4) |
| Dynamics (treadmilling & condensation) | FtsZ protofilaments treadmill and are condensed into a functional Z‑ring by Z‑binding proteins (ZBPs); Z‑ring condensation is essential for cytokinesis in B. subtilis. Single‑molecule imaging distinguishes stationary ZBPs from moving PG synthase complexes. | Single‑molecule FtsZ subunit mean lifetime ≈ 8.1 s (t1/2 ≈ 5.6 s) reported by live‑cell imaging; treadmilling organizes but its coupling to synthase motion can be complex. | ZapA, SepF, EzrA, FtsA (condensers/tethers) | (squyres2021singlemoleculeimagingreveals pages 1-2, vasquez2024thezringin pages 17-19) |
| Interaction network | A modular network of membrane tethers, bundlers, and spatial regulators controls FtsZ assembly and position: FtsA/SepF anchor filaments; ZapA promotes bundling; EzrA modulates bundling and recruits PG synthases; MinCD/MinJ and Noc position the ring; metabolic cues (UgtP) influence assembly. | Many accessory factors are non‑essential singly but show synthetic interactions; some can substitute or compensate in minimized backgrounds. | FtsA, SepF, EzrA, ZapA, MinC/MinD/MinJ, Noc, UgtP | (naha2023anchorsaway pages 8-9, gulsoy2024divisomeminimizationshows pages 1-4, cameron2024insightsintothe pages 20-22) |
| Divisome assembly & PG synthases | The Z‑ring nucleates recruitment of late transmembrane PG synthases (e.g., FtsW, Pbp2B) typically via a DivIB–DivIC–FtsL scaffold; divisome assembly is temporally ordered with early (FtsZ + anchors) and late (synthases) modules. | Studies report multimeric synthesis complexes and show synthase movement that can be processive; the precise dependence of synthase motion on FtsZ treadmilling varies by system. | FtsW, Pbp2B, DivIB/DivIC/FtsL (late synthase complex) | (squyres2021singlemoleculeimagingreveals pages 1-2, gulsoy2024divisomeminimizationshows pages 1-4, cameron2024insightsintothe pages 20-22) |
| Recent advances (2023–2024) | Divisome minimization experiments indicate FtsZ + SepF can suffice for Z‑ring formation in engineered B. subtilis strains; reviews and focused studies (anchors, condensers) clarified multiple redundant tethering modes and emphasized imaging advances that resolved discontinuous, dynamic Z‑ring architecture. | Minimized strains remain viable though division frequency is reduced (suppressor mutations observed). Imaging (single‑molecule, super‑resolution) refined understanding of condensation and dynamics. | SepF emphasized as a minimal anchor in some contexts; advanced imaging methods applied. | (gulsoy2024divisomeminimizationshows pages 1-4, gulsoy2025minimizationofthe pages 2-4, naha2023anchorsaway pages 8-9, cameron2024insightsintothe pages 20-22, vasquez2024thezringin pages 17-19) |
| Drug discovery & applications | FtsZ remains a prioritized antibacterial target; reviews summarize diverse anti‑FtsZ chemotypes and emphasize species differences in FtsZ regulation that impact inhibitor design. Minimal‑divisome results and improved in vivo imaging inform both target validation and assays for on‑target activity. | Several benzamide and other scaffolds under investigation; translational challenges include species specificity and coupling to cell‑wall synthesis. | Targeting FtsZ polymerization/GTPase activity; assays leverage imaging and biochemical readouts. | (battaje2023modelsversuspathogens pages 19-20, cameron2024insightsintothe pages 20-22, gulsoy2024divisomeminimizationshows pages 1-4) |
| Key open questions | Quantitative coupling between FtsZ treadmilling and septal PG synthesis in B. subtilis remains under active study; the minimal essential anchor set across species and the molecular details of Z‑ring condensation→constriction coupling are unresolved. | Debate persists over how universally treadmilling drives synthase motion versus synthase‑driven processivity; roles of suppressor mutations in minimized systems require mechanistic follow‑up. | — | (cameron2024insightsintothe pages 20-22, vasquez2024thezringin pages 17-19, squyres2021singlemoleculeimagingreveals pages 1-2) |

Table: Concise, citation‑anchored summary table of FtsZ (P17865) in Bacillus subtilis covering identity, localization, mechanism, dynamics, interaction partners, divisome links, 2023–2024 advances, therapeutic relevance, and open questions using the provided evidence (pqac‑IDs).

Notes on evidence prioritization and limitations
- This report prioritized 2023–2024 sources where available and integrated foundational single-molecule/quantitative work in B. subtilis to provide kinetics. Some 2025 peer-reviewed content is cited when it consolidates 2024 preprint findings about minimal divisome sufficiency (FtsZ+SepF). Quantitative treadmilling speeds and enzyme kinetics can vary with imaging/assay conditions and were not consistently reported in the 2023–2024 B. subtilis-specific sources accessible here; we thus emphasized directly measured single-molecule lifetimes and robust qualitative coupling/condensation conclusions (squyres2021singlemoleculeimagingreveals pages 1-2, cameron2024insightsintothe pages 20-22, gulsoy2024divisomeminimizationshows pages 1-4, gulsoy2025minimizationofthe pages 2-4).

References

(cameron2024insightsintothe pages 20-22): Todd A. Cameron and William Margolin. Insights into the assembly and regulation of the bacterial divisome. Nature Reviews Microbiology, 22:33-45, Jul 2024. URL: https://doi.org/10.1038/s41579-023-00942-x, doi:10.1038/s41579-023-00942-x. This article has 105 citations and is from a highest quality peer-reviewed journal.
(naha2023anchorsaway pages 8-9): Arindam Naha, Daniel P. Haeusser, and William Margolin. Anchors: a way for ftsz filaments to stay membrane bound. Molecular Microbiology, 120:525-538, Apr 2023. URL: https://doi.org/10.1111/mmi.15067, doi:10.1111/mmi.15067. This article has 18 citations and is from a domain leading peer-reviewed journal.
(battaje2023modelsversuspathogens pages 19-20): Rachana Rao Battaje, Ravikant Piyush, Vidyadhar Pratap, and Dulal Panda. Models versus pathogens: how conserved is the ftsz in bacteria? Bioscience Reports, Feb 2023. URL: https://doi.org/10.1042/bsr20221664, doi:10.1042/bsr20221664. This article has 24 citations and is from a peer-reviewed journal.
(squyres2021singlemoleculeimagingreveals pages 1-2): Georgia R. Squyres, Matthew J. Holmes, Sarah R. Barger, Betheney R. Pennycook, Joel Ryan, Victoria T. Yan, and Ethan C. Garner. Single-molecule imaging reveals that z-ring condensation is essential for cell division in bacillus subtilis. Nature Microbiology, 6:553-562, Mar 2021. URL: https://doi.org/10.1038/s41564-021-00878-z, doi:10.1038/s41564-021-00878-z. This article has 75 citations and is from a highest quality peer-reviewed journal.
(gulsoy2024divisomeminimizationshows pages 1-4): Ilkay Celik Gulsoy, Terrens N. V. Saaki, Michaela Wenzel, Simon Syvertsson, Taku Morimoto, and Leendert W. Hamoen. Divisome minimization shows that ftsz and sepf can form an active z-ring, and reveals brab as a new cell division influencing protein in bacillus subtilis. bioRxiv, Jan 2024. URL: https://doi.org/10.1101/2024.01.12.575403, doi:10.1101/2024.01.12.575403. This article has 2 citations and is from a poor quality or predatory journal.
(gulsoy2025minimizationofthe pages 2-4): Ilkay Celik Gulsoy, Terrens N. V. Saaki, Michaela Wenzel, Simon Syvertsson, Taku Morimoto, Tjalling K. Siersma, and Leendert W. Hamoen. Minimization of the bacillus subtilis divisome suggests ftsz and sepf can form an active z-ring, and reveals the amino acid transporter brab as a new cell division influencing factor. PLOS Genetics, 21:e1011567, Jan 2025. URL: https://doi.org/10.1371/journal.pgen.1011567, doi:10.1371/journal.pgen.1011567. This article has 3 citations and is from a domain leading peer-reviewed journal.
(vasquez2024thezringin pages 17-19): Mónica Vásquez, Jorge Olivares, Derly Andrade Molina, Annia González-Crespo, Marcial Silva-Guzmán, José Conesa, Maria Luisa Cordero, Octavio Monasterio, and José Valpuesta. The z-ring in multicellular cyanobacteria has a dynamic pearl necklace arrangement. Aug 2024. URL: https://doi.org/10.21203/rs.3.rs-4660361/v1, doi:10.21203/rs.3.rs-4660361/v1.

Citations

naha2023anchorsaway pages 8-9
vasquez2024thezringin pages 17-19
cameron2024insightsintothe pages 20-22
squyres2021singlemoleculeimagingreveals pages 1-2
battaje2023modelsversuspathogens pages 19-20
gulsoy2024divisomeminimizationshows pages 1-4
gulsoy2025minimizationofthe pages 2-4
https://doi.org/10.1038/s41579-023-00942-x,
https://doi.org/10.1038/s41564-021-00878-z,
https://doi.org/10.1111/mmi.15067,
https://doi.org/10.1101/2024.01.12.575403,
https://doi.org/10.1371/journal.pgen.1011567,
https://doi.org/10.1038/s41567-024-02597-8,
https://doi.org/10.1042/bsr20221664,
https://doi.org/10.1038/s41564-021-00878-z
https://doi.org/10.1038/s41564-021-00878-z;
https://doi.org/10.1101/2024.01.12.575403;
https://doi.org/10.1038/s41579-023-00942-x
https://doi.org/10.1111/mmi.15067;
https://doi.org/10.1038/s41579-023-00942-x;
https://doi.org/10.1101/2024.01.12.575403
https://doi.org/10.1042/bsr20221664;
https://doi.org/10.21203/rs.3.rs-4660361/v1,

Bioreason Rl Review

(ftsZ-bioreason-rl-review.md)

BioReason-Pro RL Review: ftsZ (B. subtilis)

Source: ftsZ-deep-research-bioreason-rl.md

Correctness: 5/5
Completeness: 4/5

Functional Summary Review

The BioReason functional summary reads:

A cytoplasmic, filament-forming GTPase that builds the central scaffold for bacterial cytokinesis. Its N-terminal nucleotide-binding engine drives polymerization and turnover, while its C-terminal beta-sandwich mediates filament contacts and recruits early division factors. By assembling into a circumferential ring at the future division site, it orchestrates constriction and coordinates synthesis of the new cross wall through regulated filament treadmilling and partner recruitment.

This is an excellent and accurate summary. The description of FtsZ as a filament-forming GTPase matches the curated annotations for GTPase activity (GO:0003924) and GTP binding (GO:0005525). The Z-ring assembly at the division site aligns with cell division (GO:0051301), FtsZ-dependent cytokinesis (GO:0043093), and cell division site localization (GO:0032153). The description of protofilament treadmilling and partner recruitment accurately captures the protein polymerization function (GO:0051258) and the identical protein binding (GO:0042802) core functions.

The summary correctly identifies the cytoplasmic localization and the role in coordinating cross-wall synthesis (division septum assembly, GO:0000917). The mention of "regulated filament treadmilling" captures a key mechanistic feature of FtsZ biology.

Minor omissions: the curated review details multiple regulatory proteins (MinC/MinD, ZapA, SepF, EzrA, UgtP, MciZ) that modulate FtsZ dynamics, and the role of MciZ in inhibiting FtsZ during sporulation. These details are beyond the scope of a functional summary but do represent important biological context.

Comparison with interpro2go:

The interpro2go annotations for ftsZ provide GTPase activity (GO:0003924) and cell division (GO:0051301) among other terms. BioReason recapitulates and enriches these annotations by providing mechanistic context (treadmilling, partner recruitment, ring formation) that interpro2go cannot convey. BioReason adds value beyond interpro2go by describing the functional relationship between the GTPase domain and the C-terminal recruitment platform. Both correctly identify GTP binding and cell division as core functions.

Notes on thinking trace

The trace demonstrates strong reasoning from the tubulin/FtsZ GTPase domain through the C-terminal beta-sandwich to the biological function. The inference of polymerization-driven ring formation from the domain architecture is well-supported. The trace appropriately identifies the connection to septal peptidoglycan synthesis.

📄 View Raw YAML

id: P17865
gene_symbol: ftsZ
product_type: PROTEIN
status: DRAFT
taxon:
  id: NCBITaxon:224308
  label: Bacillus subtilis (strain 168)
description: >-
  FtsZ is the essential bacterial tubulin homolog that serves as the master organizer of cell division
  in Bacillus subtilis. This 40 kDa GTPase polymerizes into head-to-tail protofilaments in a
  GTP-dependent manner and assembles into a dynamic ring structure (Z-ring) at the midcell division
  site adjacent to the cytoplasmic membrane. The Z-ring serves as the scaffold that recruits and
  organizes all other cell division proteins (the divisome), ultimately directing septal peptidoglycan
  synthesis and cytokinesis. FtsZ is regulated by multiple mechanisms: spatial regulators (MinC/MinD/MinJ
  system and nucleoid occlusion by Noc) ensure proper positioning at midcell; membrane anchors (FtsA,
  SepF, EzrA) tether the ring to the membrane; bundling/condensing factors (ZapA) promote ring
  stability; and developmental regulators (MciZ) inhibit division during sporulation. GTP hydrolysis
  drives protofilament treadmilling and subunit turnover, which is essential for ring dynamics and
  function. FtsZ is a validated antibacterial drug target due to its essential and conserved role
  in bacterial cell division.
existing_annotations:
- term:
    id: GO:0005525
    label: GTP binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      FtsZ is a well-established GTP-binding protein. The UniProt record documents multiple GTP
      binding residues with experimental evidence from crystal structures. GTP binding is essential
      for FtsZ polymerization and function.
    action: ACCEPT
    reason: >-
      GTP binding is a core molecular function of FtsZ. The UniProt entry states "Binds GTP and
      shows GTPase activity" and documents specific GTP-binding residues determined by X-ray
      crystallography. The deep research review confirms that "GTP binding and hydrolysis control
      filament assembly dynamics, subunit turnover, and ring remodeling" (ftsZ-deep-research-falcon.md).
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Binds GTP and shows GTPase activity"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "GTP binding and hydrolysis control filament assembly dynamics, subunit turnover, and ring remodeling"

- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      FtsZ localizes to the cytoplasm where it assembles at the inner surface of the cytoplasmic
      membrane at midcell. The UniProt record confirms cytoplasmic localization.
    action: ACCEPT
    reason: >-
      Cytoplasm is the appropriate cellular component annotation. FtsZ is a soluble cytoplasmic
      protein that assembles at the membrane-proximal midcell region. UniProt explicitly states
      FtsZ assembles at midcell at the inner surface of the cytoplasmic membrane.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Note=Assembles at midcell at the inner surface of the cytoplasmic membrane"

- term:
    id: GO:0051301
    label: cell division
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      FtsZ is essential for cell division in B. subtilis, forming the Z-ring that scaffolds
      the divisome. This is the canonical and most fundamental biological process for FtsZ.
    action: ACCEPT
    reason: >-
      Cell division is the core biological process for FtsZ. The UniProt FUNCTION states FtsZ
      is an essential cell division protein. The deep research confirms FtsZ as a conserved
      tubulin-like GTPase that scaffolds recruitment/organization of the divisome for septal
      peptidoglycan synthesis and cytokinesis (ftsZ-deep-research-falcon.md).
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis"

- term:
    id: GO:0003924
    label: GTPase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      FtsZ exhibits intrinsic GTPase activity that is essential for its function. GTP hydrolysis
      drives protofilament dynamics and treadmilling. This activity is directly demonstrated
      biochemically.
    action: ACCEPT
    reason: >-
      GTPase activity is a core molecular function of FtsZ. UniProt states FtsZ binds GTP and shows
      GTPase activity. Multiple publications demonstrate this activity, and it is critical for
      FtsZ protofilament dynamics. The deep research notes that GTP hydrolysis is required for
      polymerization dynamics and filament turnover.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Binds GTP and shows GTPase activity"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "GTP hydrolysis is required for polymerization dynamics and filament turnover"

- term:
    id: GO:0032153
    label: cell division site
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  review:
    summary: >-
      FtsZ assembles at the cell division site (midcell) to form the Z-ring. This is the
      primary subcellular localization for its function in cytokinesis.
    action: ACCEPT
    reason: >-
      The cell division site is the precise localization where FtsZ carries out its function.
      UniProt states FtsZ assembles at midcell. The deep research confirms the Z-ring forms
      at midcell adjacent to the inner membrane.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Note=Assembles at midcell at the inner surface of the cytoplasmic membrane"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "The Z-ring forms at midcell adjacent to the inner membrane"

- term:
    id: GO:0000166
    label: nucleotide binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >-
      FtsZ binds GTP specifically. The parent term nucleotide binding is technically correct
      but less informative than the more specific GTP binding annotation.
    action: ACCEPT
    reason: >-
      While nucleotide binding is correct, it is redundant with the more specific GO:0005525
      (GTP binding) annotation. However, as an IEA annotation from keyword mapping, it is
      acceptable to retain alongside the more specific IBA annotation for GTP binding.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Binds GTP and shows GTPase activity"

- term:
    id: GO:0000917
    label: division septum assembly
  evidence_type: IEA
  original_reference_id: GO_REF:0000043
  review:
    summary: >-
      FtsZ is essential for division septum assembly as the Z-ring recruits the machinery
      for septal wall synthesis. This is a core biological process for FtsZ.
    action: ACCEPT
    reason: >-
      Division septum assembly accurately describes a key biological process involving FtsZ.
      The Z-ring scaffolds recruitment of late division proteins that catalyze septal
      peptidoglycan synthesis. UniProt function states the Z-ring serves to recruit other
      cell division proteins to the septum.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "One of the functions of the FtsZ ring is to recruit other cell division proteins to the septum to produce a new cell wall between the dividing cells"

- term:
    id: GO:0003924
    label: GTPase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      Duplicate annotation for GTPase activity from automated methods. The IBA annotation
      provides equivalent support.
    action: ACCEPT
    reason: >-
      This is a duplicate of the IBA annotation for GTPase activity. Both are correct and
      represent independent evidence supporting the same molecular function. It is acceptable
      to have multiple annotations with different evidence codes for well-established functions.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Binds GTP and shows GTPase activity"

- term:
    id: GO:0005525
    label: GTP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      Duplicate annotation for GTP binding from combined automated methods. Consistent with
      the IBA annotation.
    action: ACCEPT
    reason: >-
      This IEA annotation for GTP binding is a duplicate of the IBA annotation but derived
      from different automated methods. Both correctly annotate the same molecular function
      with structural evidence.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Binds GTP and shows GTPase activity"

- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      Duplicate annotation for cytoplasm localization from automated methods.
    action: ACCEPT
    reason: >-
      This IEA annotation for cytoplasm is a duplicate of the IBA annotation but derived from
      different automated methods. Both correctly annotate the same cellular component.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Note=Assembles at midcell at the inner surface of the cytoplasmic membrane"

- term:
    id: GO:0030428
    label: cell septum
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  review:
    summary: >-
      FtsZ localizes to the cell septum where it forms the Z-ring that scaffolds septum
      formation. This is an appropriate cellular component annotation.
    action: ACCEPT
    reason: >-
      Cell septum is an appropriate localization annotation for FtsZ, which assembles at the
      septum site. The deep research confirms FtsZ scaffolds recruitment/organization of
      the divisome for septal peptidoglycan synthesis and cytokinesis.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis"

- term:
    id: GO:0032153
    label: cell division site
  evidence_type: IEA
  original_reference_id: GO_REF:0000104
  review:
    summary: >-
      Duplicate annotation for cell division site from automated transfer methods.
    action: ACCEPT
    reason: >-
      This IEA annotation duplicates the IBA annotation for cell division site. Both are
      correct and consistent with the known localization of FtsZ at midcell.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Note=Assembles at midcell at the inner surface of the cytoplasmic membrane"

- term:
    id: GO:0043093
    label: FtsZ-dependent cytokinesis
  evidence_type: IEA
  original_reference_id: GO_REF:0000104
  review:
    summary: >-
      This term directly references FtsZ and describes the cytokinesis process that depends
      on FtsZ function. This is the most specific biological process term for FtsZ.
    action: ACCEPT
    reason: >-
      FtsZ-dependent cytokinesis is the most appropriate and specific biological process
      annotation for FtsZ itself. FtsZ is essential for this process and defines the pathway.
      The deep research confirms FtsZ's essential role in bacterial cytokinesis.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis"

- term:
    id: GO:0051258
    label: protein polymerization
  evidence_type: IEA
  original_reference_id: GO_REF:0000104
  review:
    summary: >-
      FtsZ self-polymerizes into protofilaments in a GTP-dependent manner. This is a core
      aspect of FtsZ function.
    action: ACCEPT
    reason: >-
      Protein polymerization accurately describes FtsZ's ability to self-assemble into
      protofilaments. UniProt states FtsZ polymerizes to form a dynamic ring structure
      in a GTP-dependent manner. The deep research confirms FtsZ monomers bind
      GTP and assemble into polar protofilaments.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)"
      - reference_id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
        supporting_text: "FtsZ monomers bind GTP and assemble into polar protofilaments"

- term:
    id: GO:0051301
    label: cell division
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  review:
    summary: >-
      Duplicate annotation for cell division from combined automated methods.
    action: ACCEPT
    reason: >-
      This IEA annotation for cell division duplicates the IBA annotation. Both are correct
      and well-supported by the essential role of FtsZ in bacterial cell division.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site"

- term:
    id: GO:0090529
    label: cell septum assembly
  evidence_type: IEA
  original_reference_id: GO_REF:0000104
  review:
    summary: >-
      FtsZ is essential for cell septum assembly as the Z-ring initiates and scaffolds the
      septation process. This is a specific biological process term.
    action: ACCEPT
    reason: >-
      Cell septum assembly is an appropriate biological process annotation for FtsZ.
      The Z-ring formed by FtsZ recruits the divisome machinery that carries out septum
      formation. UniProt states the Z-ring functions to recruit other cell division proteins
      to the septum to produce a new cell wall between the dividing cells.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "One of the functions of the FtsZ ring is to recruit other cell division proteins to the septum to produce a new cell wall between the dividing cells"

- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:16796675
  review:
    summary: >-
      This annotation reflects FtsZ interaction with YlmF (SepF) identified by cross-linking
      and yeast two-hybrid. However, "protein binding" is too general for this well-characterized
      interaction.
    action: MODIFY
    reason: >-
      While the interaction is valid, "protein binding" is uninformative. FtsZ interacts with
      YlmF/SepF, which functions as a membrane anchor and filament bundler for FtsZ. The
      abstract states YlmF has an overlapping function with FtsA in stimulating the formation
      of Z rings. A more specific term reflecting FtsZ-anchor interaction would be appropriate,
      but since GO lacks such a term, the annotation could be retained as evidence of FtsZ's
      interaction network.
    proposed_replacement_terms:
      - id: GO:0042802
        label: identical protein binding
    supported_by:
      - reference_id: PMID:16796675
        supporting_text: "Analysis of the results identified YlmF as a new component of the FtsZ complex"

- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:17662947
  review:
    summary: >-
      This annotation reflects FtsZ interaction with UgtP, a metabolic sensor that inhibits
      FtsZ assembly. The term "protein binding" is too general.
    action: MODIFY
    reason: >-
      The interaction with UgtP is well-documented as a regulatory mechanism linking nutrient
      availability to cell division. The abstract states UgtP localizes to the division site
      in a nutrient-dependent manner and inhibits assembly of the tubulin-like cell division
      protein FtsZ. However, "protein binding" is too vague for this important regulatory
      interaction. UniProt documents the interaction.
    proposed_replacement_terms:
      - id: GO:0042802
        label: identical protein binding
    supported_by:
      - reference_id: PMID:17662947
        supporting_text: "UgtP, which localizes to the division site in a nutrient-dependent manner and inhibits assembly of the tubulin-like cell division protein FtsZ"

- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21224850
  review:
    summary: >-
      This annotation reflects FtsZ interaction with SepF, which forms large ring polymers
      that bundle and align FtsZ filaments. "Protein binding" is too general.
    action: MODIFY
    reason: >-
      The interaction between FtsZ and SepF is well-characterized. The publication shows
      SepF is able to bundle FtsZ protofilaments into strikingly long and regular tubular
      structures. While the interaction is real, "protein binding" fails to capture the
      functional significance.
    proposed_replacement_terms:
      - id: GO:0042802
        label: identical protein binding
    supported_by:
      - reference_id: PMID:21224850
        supporting_text: "able to bundle FtsZ protofilaments into strikingly long and regular tubular structures reminiscent of eukaryotic microtubules"

- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:21630458
  review:
    summary: >-
      This annotation comes from a large-scale yeast two-hybrid study in B. subtilis.
      "Protein binding" is too general for functional annotation.
    action: MARK_AS_OVER_ANNOTATED
    reason: >-
      This annotation derives from a high-throughput protein-protein interaction network
      study that identified FtsZ interactions among many others. While interactions are real,
      "protein binding" from high-throughput studies adds little functional information.
    supported_by:
      - reference_id: PMID:21630458
        supporting_text: "We have generated a protein-protein interaction network in Bacillus subtilis focused on several essential cellular processes such as cell division, cell responses to various stresses, the bacterial cytoskeleton, DNA replication and chromosome maintenance by careful application of the yeast two-hybrid approach"

- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:16796675
  review:
    summary: >-
      FtsZ forms homodimers and homopolymers. This annotation likely reflects FtsZ
      self-interaction detected in the cross-linking/mass spec study of FtsZ complexes.
    action: ACCEPT
    reason: >-
      FtsZ self-polymerization is essential for Z-ring formation. UniProt states FtsZ is a
      homodimer that polymerizes to form a dynamic ring structure in a strictly GTP-dependent
      manner. The IntAct database records FtsZ-FtsZ interactions with 6 experiments.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)"

- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:17662947
  review:
    summary: >-
      This annotation may reflect FtsZ self-interaction detected in the context of
      studying UgtP regulation of FtsZ assembly.
    action: ACCEPT
    reason: >-
      FtsZ homo-oligomerization is well-established and central to its function. The study
      examining UgtP inhibition of FtsZ assembly would have detected FtsZ self-interactions
      as part of the polymerization assays.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)"

- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:21224850
  review:
    summary: >-
      FtsZ self-polymerization is essential for forming the protofilaments that are bundled
      by SepF. This study directly examined FtsZ polymerization.
    action: ACCEPT
    reason: >-
      The publication explicitly studied FtsZ polymerization and its bundling by SepF.
      The methods describe FtsZ polymerization and GTPase assays with FtsZ. Self-interaction
      is a prerequisite for the bundled structures observed.
    supported_by:
      - reference_id: PMID:21224850
        supporting_text: "B. subtilis FtsZ was purified as described previously (Wang and Lutkenhaus, 1993; Scheffers, 2008)"

- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:21630458
  review:
    summary: >-
      FtsZ self-interaction detected in the high-throughput two-hybrid network study.
    action: ACCEPT
    reason: >-
      FtsZ homo-oligomerization is a well-established core function. Detection in the
      two-hybrid study is consistent with established biochemistry. IntAct records 6
      experiments supporting FtsZ-FtsZ interaction.
    supported_by:
      - reference_id: UniProt:P17865
        supporting_text: "Polymerizes to form a dynamic ring structure in a strictly GTP-dependent manner (By similarity)"

- term:
    id: GO:0051301
    label: cell division
  evidence_type: EXP
  original_reference_id: PMID:22298780
  review:
    summary: >-
      This study examined the role of the FtsZ C-terminal variable region in lateral
      interactions between protofilaments and Z-ring integrity, directly demonstrating
      FtsZ's role in cell division.
    action: ACCEPT
    reason: >-
      The publication provides direct experimental evidence for FtsZ's role in cell
      division in B. subtilis. It states bacterial cell division typically requires
      assembly of the cytoskeletal protein FtsZ into a ring at the nascent division site
      and shows that C-terminal mutations cause a low frequency of FtsZ ring formation
      and a high degree of filamentation.
    supported_by:
      - reference_id: PMID:22298780
        supporting_text: "Bacterial cell division typically requires assembly of the cytoskeletal protein FtsZ into a ring (Z-ring) at the nascent division site that serves as a foundation for assembly of the division apparatus"

- term:
    id: GO:0003924
    label: GTPase activity
  evidence_type: IDA
  original_reference_id: PMID:23577149
  review:
    summary: >-
      This study directly assayed FtsZ GTPase activity and critical concentration as
      part of characterizing MinC-FtsZ interactions. The GTPase activity measurements
      provide direct experimental evidence.
    action: ACCEPT
    reason: >-
      The publication directly measured GTPase activity of wild-type and mutant FtsZ.
      The methods describe GTPase Activity and Critical Concentration assays, and
      results include GTPase activity measurements of FtsZ mutants. This provides direct
      biochemical evidence (IDA) for the GTPase molecular function.
    supported_by:
      - reference_id: PMID:23577149
        supporting_text: "GTPase activity and Cc of FtsZ mutants"

- term:
    id: GO:0051301
    label: cell division
  evidence_type: IMP
  original_reference_id: PMID:18573169
  review:
    summary: >-
      This study used FtsZ depletion to examine YycG kinase function, providing mutant
      phenotype evidence for FtsZ's role in cell division.
    action: ACCEPT
    reason: >-
      The abstract describes using FtsZ-depleted, septum-less cells to study YycG
      kinase activity, indicating that FtsZ depletion prevents septum formation. This
      mutant phenotype evidence (IMP) supports the cell division annotation.
    supported_by:
      - reference_id: PMID:18573169
        supporting_text: "RT-PCR quantification of YycF approximately PO(4)-regulated gene transcription, in wild type and FtsZ-depleted, septum-less cells, indicated that YycG kinase activity on YycF is dependent on YycG localization to a division septum"

- term:
    id: GO:0030428
    label: cell septum
  evidence_type: IDA
  original_reference_id: PMID:18573169
  review:
    summary: >-
      The study examining YycG localization demonstrates that the septum forms at the
      FtsZ ring location, supporting FtsZ localization at the cell septum.
    action: ACCEPT
    reason: >-
      The publication shows that YycG sensor histidine kinase is a component of the
      division septum and that its activity depends on localization to the septum
      where FtsZ forms the Z-ring. The study of septum-less cells in FtsZ-depleted
      conditions confirms FtsZ's role at the septum.
    supported_by:
      - reference_id: PMID:18573169
        supporting_text: "YycG sensor histidine kinase is a component of the division septum in growing cells"

references:
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000043
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
  findings: []
- id: GO_REF:0000104
  title: Electronic Gene Ontology annotations created by transferring manual GO annotations
    between related proteins based on shared sequence features
  findings: []
- id: GO_REF:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: PMID:16796675
  title: A new FtsZ-interacting protein, YlmF, complements the activity of FtsA during
    progression of cell division in Bacillus subtilis.
  findings:
    - statement: YlmF (SepF) identified as FtsZ-interacting protein
      supporting_text: "Analysis of the results identified YlmF as a new component of the FtsZ complex"
    - statement: YlmF has overlapping function with FtsA in Z-ring formation
      supporting_text: "YlmF has an overlapping function with FtsA in stimulating the formation of Z rings in B. subtilis"
- id: PMID:17662947
  title: A metabolic sensor governing cell size in bacteria.
  findings:
    - statement: UgtP identified as metabolic sensor that inhibits FtsZ assembly
      supporting_text: "UgtP, which localizes to the division site in a nutrient-dependent manner and inhibits assembly of the tubulin-like cell division protein FtsZ"
    - statement: Links nutrient availability to cell division control
      supporting_text: "Nutrient availability is one of the strongest determinants of cell size"
- id: PMID:18573169
  title: A sensor histidine kinase co-ordinates cell wall architecture with cell division
    in Bacillus subtilis.
  findings:
    - statement: YycG kinase localizes to division septum
      supporting_text: "YycG sensor histidine kinase is a component of the division septum in growing cells"
    - statement: FtsZ depletion produces septum-less cells
      supporting_text: "wild type and FtsZ-depleted, septum-less cells"
- id: PMID:21224850
  title: Large ring polymers align FtsZ polymers for normal septum formation.
  findings:
    - statement: SepF forms large ring polymers that bundle FtsZ protofilaments
      supporting_text: "able to bundle FtsZ protofilaments into strikingly long and regular tubular structures reminiscent of eukaryotic microtubules"
    - statement: SepF rings required for regular arrangement of FtsZ filaments
      supporting_text: "We propose that SepF rings are required for the regular arrangement of FtsZ filaments"
- id: PMID:21630458
  title: An expanded protein-protein interaction network in Bacillus subtilis reveals
    a group of hubs.
  findings:
    - statement: High-throughput protein-protein interaction network in B. subtilis
      supporting_text: "We have generated a protein-protein interaction network in Bacillus subtilis focused on several essential cellular processes such as cell division, cell responses to various stresses, the bacterial cytoskeleton, DNA replication and chromosome maintenance by careful application of the yeast two-hybrid approach"
    - statement: FtsZ identified as hub protein in cell division pathway
      supporting_text: "A striking feature of the network is a group of highly connected hubs (GoH) linking many different cellular processes"
- id: PMID:22298780
  title: Extreme C terminus of bacterial cytoskeletal protein FtsZ plays fundamental
    role in assembly independent of modulatory proteins.
  findings:
    - statement: C-terminal variable region mediates lateral interactions between FtsZ polymers
      supporting_text: "residues at the C terminus of Bacillus subtilis FtsZ (C-terminal variable region (CTV)) are both necessary and sufficient for stimulating lateral interactions in vitro in the absence of modulatory proteins"
    - statement: CTV mutations cause filamentation and reduced Z-ring formation
      supporting_text: "B. subtilis cells expressing the B. subtilis FtsZ chimera had a low frequency of FtsZ ring formation and a high degree of filamentation relative to wild-type cells"
- id: PMID:23577149
  title: Genetic and biochemical characterization of the MinC-FtsZ interaction in
    Bacillus subtilis.
  findings:
    - statement: MinC inhibits FtsZ polymerization
      supporting_text: "The best studied of these regulators is MinC, an inhibitor of FtsZ polymerization that plays a crucial role in the spatial control of Z ring formation"
    - statement: Identified MinC binding site on FtsZ
      supporting_text: "determine the binding site for MinC on B. subtilis FtsZ"
    - statement: GTPase activity measured for FtsZ mutants
      supporting_text: "GTPase activity and Cc of FtsZ mutants"
- id: UniProt:P17865
  title: UniProt entry for B. subtilis FtsZ
  findings:
    - statement: Essential cell division protein forming Z-ring
      supporting_text: "Essential cell division protein that forms a contractile ring structure (Z ring) at the future cell division site"
    - statement: GTP binding and GTPase activity
      supporting_text: "Binds GTP and shows GTPase activity"
    - statement: Interacts with FtsA, SepF, EzrA, ZapA, UgtP
      supporting_text: "Interacts directly with several other division proteins (By similarity). Interacts with FtsA"
    - statement: Regulated by MciZ during sporulation
      supporting_text: "During sporulation, is negatively regulated by MciZ, which binds to FtsZ and inhibits its polymerization and the formation of the Z ring"
    - statement: Crystal structure solved to 1.7 angstroms
      supporting_text: "PDB; 2VXY; X-ray; 1.70 A; A=1-382"
- id: file:BACSU/ftsZ/ftsZ-deep-research-falcon.md
  title: Deep research review of FtsZ in B. subtilis
  findings:
    - statement: FtsZ is a conserved tubulin-like GTPase essential for bacterial cell division
      supporting_text: "FtsZ is a conserved tubulin-like GTPase that polymerizes into head-to-tail protofilaments and assembles at midcell into the Z-ring, which scaffolds recruitment/organization of the divisome for septal peptidoglycan synthesis and cytokinesis"
    - statement: GTP binding and hydrolysis control filament dynamics
      supporting_text: "GTP binding and hydrolysis control filament assembly dynamics, subunit turnover, and ring remodeling"
    - statement: Multiple membrane tethers anchor the Z-ring
      supporting_text: "FtsZ lacks an intrinsic membrane anchor and is tethered via membrane-associated partners, notably FtsA and SepF, with EzrA also acting as a multifunctional tether/regulator in B. subtilis"

core_functions:
  - molecular_function:
      id: GO:0003924
      label: GTPase activity
    description: >-
      FtsZ is a tubulin-like GTPase whose enzymatic activity drives protofilament
      dynamics through GTP hydrolysis. This is the primary molecular function.
    directly_involved_in:
      - id: GO:0043093
        label: FtsZ-dependent cytokinesis
    locations:
      - id: GO:0032153
        label: cell division site

  - molecular_function:
      id: GO:0042802
      label: identical protein binding
    description: >-
      FtsZ homo-oligomerization is essential for protofilament formation and
      Z-ring assembly. This self-polymerization underlies all downstream functions.
    directly_involved_in:
      - id: GO:0051258
        label: protein polymerization
    locations:
      - id: GO:0032153
        label: cell division site

suggested_questions:
  - question: >-
      What are the precise roles of different FtsZ tethering proteins (FtsA, SepF, EzrA)
      in regulating Z-ring architecture and dynamics? Recent studies show redundant
      membrane tethering systems with partially overlapping functions.
  - question: >-
      How does FtsZ treadmilling mechanistically couple to peptidoglycan synthase
      activity during septation? The coupling between Z-ring dynamics and septal
      wall synthesis remains an active area of investigation.

suggested_experiments:
  - description: >-
      Single-molecule imaging of FtsZ dynamics in strains lacking individual or
      combinations of regulatory proteins (EzrA, ZapA, SepF) to determine their
      specific contributions to ring condensation. Recent work shows Z-ring
      condensation is essential but the relative roles of individual ZBPs are
      not fully resolved.

proposed_new_terms: []

ftsZ

Gene Description

Existing Annotations Review

Core Functions

FtsZ is a tubulin-like GTPase whose enzymatic activity drives protofilament dynamics through GTP hydrolysis. This is the primary molecular function.

FtsZ homo-oligomerization is essential for protofilament formation and Z-ring assembly. This self-polymerization underlies all downstream functions.

References

Suggested Questions for Experts

Suggested Experiments

📚 Additional Documentation

Deep Research Bioreason

BioReason Chat Export

Thinking Trace

Functional Summary

UniProt Summary

InterPro Domains

GO Terms

Deep Research Bioreason Rl

BioReason Chat Export

Thinking Trace

Functional Summary

UniProt Summary

InterPro Domains

GO Terms

Deep Research Falcon

Question

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Output

Gene Research for Functional Annotation

⚠️ CRITICAL: Gene/Protein Identification Context

Target Gene/Protein Identity (from UniProt):

MANDATORY VERIFICATION STEPS:

If Gene Symbol is Ambiguous or You Cannot Find Relevant Literature:

Research Target:

Citations

Bioreason Rl Review

BioReason-Pro RL Review: ftsZ (B. subtilis)

Functional Summary Review

Notes on thinking trace

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