MinD is a septum site-determining protein and ParA-family Walker-type ATPase essential for correct placement of the bacterial cell division site. MinD acts in concert with MinC to form an inhibitory complex that blocks polar Z ring formation, preventing aberrant division at cell poles. The ATP-bound form of MinD dimerizes and recruits MinC to the membrane, where MinC directly inhibits FtsZ polymerization. Unlike E. coli, B. subtilis lacks MinE and instead uses MinJ as the topological determinant that bridges MinD/MinC to DivIVA, which senses negative membrane curvature at poles and septa. MinD's ATPase cycle controls membrane residence time and drives dynamic polar/septal enrichment patterns that prevent polar septum formation and promote divisome disassembly after cytokinesis. Loss of MinD leads to minicell formation due to aberrant polar division.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005524 ATP binding | IBA GO_REF:0000033 | ACCEPT | Summary: MinD is a ParA-family Walker-type ATPase with a well-characterized ATP binding site at residues 11-18 (P-loop motif). ATP binding is essential for MinD function and drives dimerization, which is required for MinC recruitment and membrane association. This is a core molecular function supported by extensive phylogenetic and biochemical evidence. Reason: ATP binding is a core molecular function of MinD. The protein contains a characteristic P-loop NTPase domain (InterPro: IPR027417) with an ATP binding site at residues 11-18 documented in UniProt. The IBA annotation is well-supported by phylogenetic inference and aligns with the conserved function across MinD family proteins. Biochemical studies confirm ATP binding is essential for MinD dimerization and function. Supporting Evidence: UniProt:Q01464 BINDING 11..18 /ligand="ATP" /ligand_id="ChEBI:CHEBI:30616" file:BACSU/minD/minD-deep-research-falcon.md MinD is an ATPase whose hydrolysis is strongly stimulated by membrane binding |
| GO:0016887 ATP hydrolysis activity | IBA GO_REF:0000033 | ACCEPT | Summary: MinD possesses intrinsic ATP hydrolysis activity that is membrane-activated. Recent biochemical studies report kcat of approximately 36.27 h^-1 in liposome assays. The ATPase cycle controls membrane residence time and is essential for MinD patterning and function in division site selection. Reason: ATP hydrolysis is a core enzymatic function of MinD essential for its role in division site selection. Unlike E. coli MinD which requires MinE for stimulation, B. subtilis MinD ATPase is activated by membrane binding alone. The ATPase cycle drives the dynamic membrane association/dissociation that creates the spatial gradients necessary for correct division site positioning. This IBA annotation is strongly supported by phylogenetic inference and recent biochemical characterization. Supporting Evidence: file:BACSU/minD/minD-deep-research-falcon.md MinD ATPase activity is strongly stimulated by membrane binding, with kcat approximately 36.27 h^-1 in liposome assays PMID:33849976 MinD, a protein that belongs to the WACA (Walker A cytomotive ATPase) family |
| GO:0005829 cytosol | IBA GO_REF:0000033 | ACCEPT | Summary: MinD is found in the cytosol as part of its dynamic cycling between cytoplasm and membrane. The ATP-free monomeric form of MinD is predominantly cytosolic, while ATP-bound dimeric MinD associates with the membrane. This dynamic localization is essential for MinD function. Reason: MinD cycles between cytosol and membrane as part of its functional mechanism. Single-molecule tracking studies show that MinD exists in multiple diffusion states including a fast cytosolic fraction (D approximately 0.60 um^2/s). The cytosolic pool represents the ATP-free/monomeric form that is part of the functional cycle. This annotation correctly captures one aspect of MinD's dynamic localization. Supporting Evidence: file:BACSU/minD/minD-deep-research-falcon.md Representative diffusion-state fractions for MinD populations (WT example): fast approximately 22.3% at D approximately 0.60 um^2 s^-1 |
| GO:0009898 cytoplasmic side of plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: MinD localizes to the cytoplasmic side of the plasma membrane via two C-terminal amphipathic helices (MTS1 and MTSL). Membrane association is enhanced in the ATP-bound dimeric state and is essential for recruiting MinC to inhibit polar FtsZ ring formation. MinD enriches at poles and active division sites. Reason: Membrane localization is a core aspect of MinD function. B. subtilis MinD possesses two C-terminal amphipathic alpha-helices (MTS1 and MTSL) that mediate membrane targeting. Unlike E. coli MinD which oscillates rapidly pole-to-pole, B. subtilis MinD forms polar and septal enrichments with dynamic recruitment to division sites. UniProt annotates MinD as a peripheral membrane protein associated with the cell membrane. Supporting Evidence: UniProt:Q01464 SUBCELLULAR LOCATION: Cell membrane; Peripheral membrane protein. PMID:28674273 Bacillus subtilis MinD has two amphipathic Ξ±-helices rich in basic amino acid residues at its C-terminus file:BACSU/minD/minD-deep-research-falcon.md In B. subtilis MinD enriches at poles and active division sites (septal enrichment) |
| GO:0000166 nucleotide binding | IEA GO_REF:0000043 | ACCEPT | Summary: This is a parent term of GO:0005524 (ATP binding). MinD specifically binds ATP through its P-loop motif. The more specific ATP binding annotation already captures the core function. Reason: This IEA annotation from UniProtKB keyword mapping is correct but less specific than the ATP binding (GO:0005524) annotation already present via IBA evidence. Since MinD is specifically an ATP-binding ATPase, this broader term is technically accurate but redundant with the more informative ATP binding annotation. Acceptable to retain as it does not contradict other annotations. |
| GO:0000917 division septum assembly | IEA GO_REF:0000043 | MODIFY | Summary: MinD is involved in the regulation of division septum assembly, specifically by preventing inappropriate polar septum formation and promoting divisome disassembly after cytokinesis. However, MinD's role is inhibitory/regulatory rather than directly assembling the septum. Reason: While MinD is clearly involved in division septum-related processes, the term 'division septum assembly' (GO:0000917) implies direct participation in building the septum. MinD's actual role is to NEGATIVELY regulate septum formation at inappropriate sites (cell poles) and to promote disassembly of the divisome after septation. More appropriate terms would be 'regulation of division septum assembly' (GO:0032955) or 'negative regulation of division septum assembly' (GO:0010974), or 'division septum site selection' (GO:0000918). The MinCDJ system prevents polar Z-ring activity and promotes divisome disassembly. Proposed replacements: division septum site selection regulation of division septum assembly Supporting Evidence: PMID:20352045 the main function of the Min system is to prevent minicell formation adjacent to recently completed division sites by promoting the disassembly of the cytokinetic ring file:BACSU/minD/minD-deep-research-falcon.md MinCDJ acting downstream of site selection to prevent re-initiation and to assist divisome disassembly |
| GO:0005524 ATP binding | IEA GO_REF:0000043 | ACCEPT | Summary: Duplicate of the IBA annotation for ATP binding. This IEA from UniProtKB keyword mapping confirms the same core function. Reason: This is a duplicate annotation with the same GO term (GO:0005524) as the IBA annotation but with IEA evidence from UniProtKB keyword mapping. Duplicates with different evidence sources are acceptable and provide independent support. ATP binding is unambiguously a core function of MinD. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: MinD associates with the plasma membrane. This is consistent with the more specific annotation GO:0009898 (cytoplasmic side of plasma membrane) which better captures the topology. Reason: This annotation is correct - MinD is a peripheral membrane protein that associates with the plasma membrane via C-terminal amphipathic helices. While less specific than GO:0009898 (cytoplasmic side of plasma membrane), it is not incorrect. The IEA annotation from UniProtKB subcellular location mapping is acceptable alongside the more specific IBA annotation. Supporting Evidence: UniProt:Q01464 SUBCELLULAR LOCATION: Cell membrane; Peripheral membrane protein. |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000002 | ACCEPT | Summary: Duplicate of the IBA annotation for ATP hydrolysis activity. This IEA from InterPro mapping provides independent support for this core enzymatic function. Reason: This is a duplicate annotation with the same GO term (GO:0016887) as the IBA annotation but with IEA evidence from InterPro (IPR010223 MinD domain). Duplicates with different evidence sources are acceptable. ATP hydrolysis activity is well-established for MinD. |
| GO:0032506 cytokinetic process | IEA GO_REF:0000117 | ACCEPT | Summary: MinD is involved in cytokinetic processes through its role in regulating division site selection and Z-ring positioning. This is a broad term that captures MinD's involvement in cell division. Reason: MinD clearly functions in cytokinesis by regulating where cell division occurs. The MinCDJ system prevents polar division and promotes divisome disassembly. While this is a relatively broad term, it accurately reflects MinD's biological role. More specific annotations for negative regulation of FtsZ-dependent cytokinesis could be considered but this annotation is not incorrect. Supporting Evidence: PMID:20352045 the main function of the Min system is to prevent minicell formation adjacent to recently completed division sites by promoting the disassembly of the cytokinetic ring |
| GO:0051301 cell division | IEA GO_REF:0000043 | ACCEPT | Summary: MinD is involved in cell division, specifically in regulating division site selection to ensure proper midcell septation. This broad term is accurate but non-specific. Reason: MinD is clearly involved in cell division - it is a septum site-determining protein whose loss leads to minicell formation and cell division defects. This broad biological process annotation is accurate. More specific annotations exist (cytokinetic process, division septum site selection) but this does not make the broader annotation wrong. Supporting Evidence: UniProt:Q01464 RecName: Full=Septum site-determining protein MinD; AltName: Full=Cell division inhibitor MinD |
| GO:0005515 protein binding | IPI PMID:25374563 Protein-tyrosine phosphorylation interaction network in Baci... | KEEP AS NON CORE | Summary: This annotation captures MinD's interaction with ywqD (PtkA, a tyrosine kinase; UniProtKB:P96716). The study shows MinD acts as a scaffold protein that tethers PtkA at the cell pole and can activate PtkA autophosphorylation in vitro. However, this is a secondary/moonlighting function rather than MinD's core evolved function. Reason: The interaction between MinD and PtkA (ywqD) is documented by yeast two-hybrid, far-Western blotting, and in vivo localization studies in PMID:25374563. MinD acts as a platform protein that anchors PtkA at the cell pole and can activate PtkA autophosphorylation. However, this represents a secondary scaffolding function rather than MinD's core evolved function in division site selection. The generic 'protein binding' term also fails to capture the specific nature of this interaction. Consider modifying to a more informative term if available. Supporting Evidence: PMID:25374563 MinD could act as a platform protein that would tether PtkA at a specific cellular area. Additionally MinD would also act as an activator of PtkA for signal transmission to DivIVA. PMID:25374563 Incubation of PtkA with increasing amounts of MinD activated its autophosphorylation, indicating that MinD is able to act as modulator of PtkA activity similar to TkmA |
| GO:0005515 protein binding | IPI PMID:25374563 Protein-tyrosine phosphorylation interaction network in Baci... | ACCEPT | Summary: This annotation captures MinD's interaction with MinC (UniProtKB:Q01463). The MinD-MinC interaction is a CORE functional interaction - ATP-bound MinD dimers recruit MinC to the membrane where MinC acts as the direct inhibitor of FtsZ polymerization. This is the central mechanism of the Min system. Reason: The MinD-MinC interaction is the core functional interaction of MinD. ATP-bound MinD dimers recruit MinC to form the MinCD inhibitory complex that blocks polar Z ring formation. This interaction is documented extensively in the literature and in IntAct (3 experiments). While 'protein binding' is a generic term, the annotation correctly captures a functionally critical interaction. UniProt explicitly documents the MinC interaction. Supporting Evidence: UniProt:Q01464 SUBUNIT: Interacts with MinC and FtsZ (By similarity). Interacts with MinJ. UniProt:Q01464 INTERACTION: Q01464; Q01463: minC; NbExp=3; IntAct=EBI-6502875, EBI-9304968 PMID:20352045 MinD is a membrane-associated ATPase that sequesters MinC to the membrane interface, allowing it to interact with FtsZ PMID:25374563 In this assay we detected the expected MinD-MinC complex |
| GO:0000918 division septum site selection | TAS PMID:33849976 Dynamics of the Bacillus subtilis Min System. | NEW | Summary: MinD is directly involved in division septum site selection as part of the MinCDJ system. This is the core biological process function of MinD - ensuring that cell division occurs at midcell rather than at the poles. Reason: This annotation is not currently in the GOA file but should be added. Division septum site selection (GO:0000918) precisely captures MinD's core biological role. The MinCDJ system functions to mark and enforce the midcell division site while preventing polar division. This term is more specific and accurate than the current 'division septum assembly' annotation. Supporting Evidence: UniProt:Q01464 RecName: Full=Septum site-determining protein MinD file:BACSU/minD/minD-deep-research-falcon.md MinD is a ParA/MinD-family Walker-type P-loop NTPase in Bacillus subtilis strain 168 that participates in the MinCDJ/DivIVA system for division-site selection PMID:20352045 the main function of the Min system is to prevent minicell formation adjacent to recently completed division sites |
| GO:2000245 negative regulation of FtsZ-dependent cytokinesis | TAS PMID:20352045 The MinCDJ system in Bacillus subtilis prevents minicell for... | NEW | Summary: MinD, through its recruitment of MinC, negatively regulates FtsZ-dependent cytokinesis at polar sites. MinC is the direct inhibitor of FtsZ polymerization, and MinD positions this inhibitor at poles and completed septa. Reason: This term precisely captures MinD's role in preventing polar FtsZ ring formation. The MinCD complex blocks FtsZ polymerization at poles, preventing minicell formation. This is a core function of the Min system that should be annotated. Supporting Evidence: PMID:20352045 the main function of the Min system is to prevent minicell formation adjacent to recently completed division sites by promoting the disassembly of the cytokinetic ring file:BACSU/minD/minD-deep-research-falcon.md MinD recruits and activates MinC, the direct inhibitor of FtsZ polymerization, to suppress polar Z-ring formation |
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Download this section (compressed HTML)Q: What are the precise kinetic parameters of B. subtilis MinD membrane binding and ATPase activity under physiological conditions? Recent preprints provide in vitro measurements but physiological relevance needs confirmation.
Q: How does the MinD-PtkA interaction contribute to cell division regulation in vivo, and is DivIVA phosphorylation by PtkA functionally significant? PMID:25374563 shows MinD can scaffold and activate PtkA, which phosphorylates DivIVA, but biological significance is unclear.
Experiment: Quantitative live-cell imaging of MinD dynamics during the cell cycle using fluorescent protein fusions and single-molecule tracking to confirm gradient formation patterns in B. subtilis. This would validate the dynamic septal enrichment model proposed by recent studies and distinguish B. subtilis MinD behavior from E. coli oscillation.
Hypothesis: MinD's ATPase cycling drives the dynamic septal enrichment patterns observed in B. subtilis, distinct from the rapid pole-to-pole oscillation in E. coli.
Experiment: Site-directed mutagenesis of MinD ATP binding site residues combined with localization studies to confirm the role of ATPase cycling in membrane association patterns. This would provide direct evidence that ATPase activity drives MinD patterning as proposed by biochemical studies.
Hypothesis: ATPase activity is required for MinD patterning and membrane residence dynamics.
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