Bacterial divisome peptidoglycan polymerization and crosslinking

A focused FtsW/class-B-PBP septal peptidoglycan-synthesis mechanism with two required reactions: lipid-II-derived glycan polymerization and serine-dependent D,D peptide crosslinking. FtsW requires a compatible bPBP activation interface, whereas crosslink catalysis can be supplied conditionally by Bacillus PBP3 while physical PBP2B remains present. The acceptor amino group may lie on a stem peptide or an attached bridge; mDAP is not universal. Sampled E. coli, Bacillus, Staphylococcus and Streptococcus implementations illustrate this mechanism, which is not a universal description of bacterial division. Precursor supply, divisome positioning and upstream activation, class-A-PBP alternatives and cell separation lie outside this focused boundary.

MODULE:bacterial_divisome_peptidoglycan_transpeptidationCOMPLETECONCRETEBiological Processmodules/bacterial_divisome_peptidoglycan_transpeptidation.yaml
division septum assemblyGO:0000917 peptidoglycan biosynthetic processGO:0009252
GO:0000917
division septum assembly
Defines septum assembly as process context; it does not specify a universally required FtsI implementation.
GO:0009252
peptidoglycan biosynthetic process
Defines peptidoglycan synthesis from lipid II.
file:genes/ECOLI/ftsI/ftsI-ai-review.yaml
ECOLI ftsI gene review
The completed E. coli ftsI review grounds FtsI as the PBP3 septal D,D-transpeptidase.
file:genes/ECOLI/ftsW/ftsW-ai-review.yaml
ECOLI ftsW gene review
The completed E. coli ftsW review grounds FtsW as the SEDS-family septal peptidoglycan glycosyltransferase.
PMID:6450748
Evidence for involvement of penicillin-binding protein 3 in murein synthesis during septation but not during cell elongation.
Supports the septation-specific requirement for PBP3 activity.
PMID:9603865
FtsI and FtsW are localized to the septum in Escherichia coli.
Establishes septal localization of FtsI and FtsW.
PMID:20847002
The integral membrane FtsW protein and peptidoglycan synthase PBP3 form a subcomplex in Escherichia coli.
Establishes the FtsW-FtsI/PBP3 subcomplex.
PMID:27525505
SEDS proteins are a widespread family of bacterial cell wall polymerases.
Establishes the SEDS protein family as peptidoglycan glycosyltransferases.
PMID:40879381
Peptidoglycan polymerase function and regulation.
The comparative review distinguishes SEDS GT119 polymerases from class-A-PBP GT51 architecture. Similar PG output does not make the families interchangeable.
a C1-type GTase from the CAZy GT119 family
PMID:38821027
Stay on track - revelations of bacterial cell wall synthesis enzymes and things that go by single-molecule imaging.
The review compares synthase dynamics across diderm and monoderm models. Conserved septal synthesis does not imply a universal two-track motion mechanism.
the movement occurs at two distinct speeds
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Purified FtsW requires a compatible bPBP for polymerization; its partner may be catalytically inactive. StPBP2x crosslink products are separately measured, so polymerization does not prove complete crosslinked output.
its polymerase activity requires complex formation with its partner class B PBP.
PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
In the tested Bacillus subtilis mutants, PBP3 supplies catalytic capacity when PBP2B catalysis is disabled; the PBP2B protein still provides an essential structural role.
a catalytically inactive mutant of PBP 2B supports cell division
PMID:41118402
Molecular dissection of Class A PBP function uncovers novel features of the non-canonical Clostridioides difficile divisome complex.
C. difficile vegetative cell division uses a class-A-PBP1-centered mechanism and bounds claims that FtsW/FtsI is universally required. This alternative lies outside the focused FtsW/bPBP pair.
it lacks functional orthologs of the septal peptidoglycan-synthesizing enzymes, FtsW and FtsI.

The two original reaction nodes and E. coli annoton identifiers are retained. Nine completed reference-protein reviews ground four compatible native pairs and one conditional PBP3 catalytic substitute. Family membership identifies candidates, not partner compatibility or catalytic competence. The checker uses production compile_node/is_satisfied with an explicit active-unit and proposed-function-aware oracle; one pair/taxon witness is shared across both reactions. Same-taxon constraints bound native panel inference, not all possible heterologous biochemistry: PMID30692671 directly demonstrated StFtsW activation by pneumococcal PBP2x. FtsW polymerization alone does not establish crosslinked output; StPBP2x crosslinking also works on glycan supplied by other polymerases. No stable FtsW/PBP2B/PBP3 trimer is asserted. Comparative review findings and eight original curated reference entries are retained unchanged.

12Nodes
2Parts
2Variant Sets
9Variants
10Annotons
1Connections

Derived QC

Recommended-field compliance

73.3% recommended fields populated
  • references[8] · findings (0/1)
  • references[9] · findings (0/1)
  • references[10] · findings (0/1)
  • references[13] · findings (0/1)

Module deep research

✗ none found

No MODULE:bacterial_divisome_peptidoglycan_transpeptidation deep-research report alongside the module YAML.

Leaf nodes lacking representative members

✓ every leaf node grounds to a representative protein.

Template conformance

✓ every declared conforms_to bundle matches its template motif.

Function consistency and core coverage

4 gene-function check(s) reflected in core functions · 0 conflict(s) · 14 evidence or coverage gap(s) (22 comparison(s))

Retained noncore functions are reported separately; they do not require promotion to core functions. Support from representative genes does not establish conservation across the whole family. Missing reviews or identifiers leave a claim unverified.

AnnotonParticipantFunctionAssessment
ftsw_glycosyltransferase PROTEIN_COMPLEX
Gene 		peptidoglycan glycosyltransferase activity
GO:0008955 		Participant Unchecked
No direct UniProt participant to compare. Abstract selectors and complex-wide activities cannot be inferred from donor or subunit gene reviews.
ftsw_glycosyltransferase/ecoli_ftsw_catalyst P0ABG4
UniProtKB:P0ABG4
Family Representative 		peptidoglycan glycosyltransferase activity
GO:0008955 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
bacsu_ftsw_glycosyltransferase PROTEIN_COMPLEX
Gene 		peptidoglycan glycosyltransferase activity
GO:0008955 		Participant Unchecked
No direct UniProt participant to compare. Abstract selectors and complex-wide activities cannot be inferred from donor or subunit gene reviews.
bacsu_ftsw_glycosyltransferase/bacsu_ftsw_catalyst O07639
UniProtKB:O07639
Family Representative 		peptidoglycan glycosyltransferase activity
GO:0008955 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
staa8_ftsw_glycosyltransferase PROTEIN_COMPLEX
Gene 		peptidoglycan glycosyltransferase activity
GO:0008955 		Participant Unchecked
No direct UniProt participant to compare. Abstract selectors and complex-wide activities cannot be inferred from donor or subunit gene reviews.
staa8_ftsw_glycosyltransferase/staa8_ftsw_catalyst Q2G2C2
UniProtKB:Q2G2C2
Family Representative 		peptidoglycan glycosyltransferase activity
GO:0008955 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
strt2_ftsw_glycosyltransferase PROTEIN_COMPLEX
Gene 		peptidoglycan glycosyltransferase activity
GO:0008955 		Participant Unchecked
No direct UniProt participant to compare. Abstract selectors and complex-wide activities cannot be inferred from donor or subunit gene reviews.
strt2_ftsw_glycosyltransferase/strt2_ftsw_catalyst Q5M5I9
UniProtKB:Q5M5I9
Family Representative 		peptidoglycan glycosyltransferase activity
GO:0008955 		Core Supported
The GO molecular function is reflected in core_functions (exact term or a reviewed subclass).
ftsi_dd_transpeptidase P0AD68
UniProtKB:P0AD68
Family Representative 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
A gene review exists, but this function lacks a GO identifier. Free-text chemistry is not automatically compared.
bacsu_dd_transpeptidase Q07868
UniProtKB:Q07868
Family Representative 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
A gene review exists, but this function lacks a GO identifier. Free-text chemistry is not automatically compared.
staa8_dd_transpeptidase Q2FZ94
UniProtKB:Q2FZ94
Family Representative 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
A gene review exists, but this function lacks a GO identifier. Free-text chemistry is not automatically compared.
strt2_dd_transpeptidase Q5M2U8
UniProtKB:Q5M2U8
Family Representative 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
A gene review exists, but this function lacks a GO identifier. Free-text chemistry is not automatically compared.
bacsu_pbp3_dd_transpeptidase P42971
UniProtKB:P42971
Family Representative 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
A gene review exists, but this function lacks a GO identifier. Free-text chemistry is not automatically compared.
ecoli_ftsw_catalyst Verified septal FtsW
PANTHER:PTHR30474:SF2
Family 		peptidoglycan glycosyltransferase activity
GO:0008955 		Family Function Unreviewed
Family review leaves GO:0008955 UNRESOLVED. Direct purified FtsW and RodA work supports the chemistry in characterized members, including different functional subfamilies; the term is not exclusive to SF2. An exhaustive catalytic assignment to all PTHR30474 members, including SpoVE, is not established here. Use verified SF2 membership together with independent polymerase and division-role evidence for a divisome selector, not the broad family alone. This uncertainty is about full propagation scope, not a denial of the experimentally supported activities.
bacsu_ftsw_catalyst Verified septal FtsW
PANTHER:PTHR30474:SF2
Family 		peptidoglycan glycosyltransferase activity
GO:0008955 		Family Function Unreviewed
Family review leaves GO:0008955 UNRESOLVED. Direct purified FtsW and RodA work supports the chemistry in characterized members, including different functional subfamilies; the term is not exclusive to SF2. An exhaustive catalytic assignment to all PTHR30474 members, including SpoVE, is not established here. Use verified SF2 membership together with independent polymerase and division-role evidence for a divisome selector, not the broad family alone. This uncertainty is about full propagation scope, not a denial of the experimentally supported activities.
staa8_ftsw_catalyst Verified septal FtsW
PANTHER:PTHR30474:SF2
Family 		peptidoglycan glycosyltransferase activity
GO:0008955 		Family Function Unreviewed
Family review leaves GO:0008955 UNRESOLVED. Direct purified FtsW and RodA work supports the chemistry in characterized members, including different functional subfamilies; the term is not exclusive to SF2. An exhaustive catalytic assignment to all PTHR30474 members, including SpoVE, is not established here. Use verified SF2 membership together with independent polymerase and division-role evidence for a divisome selector, not the broad family alone. This uncertainty is about full propagation scope, not a denial of the experimentally supported activities.
strt2_ftsw_catalyst Verified septal FtsW
PANTHER:PTHR30474:SF2
Family 		peptidoglycan glycosyltransferase activity
GO:0008955 		Family Function Unreviewed
Family review leaves GO:0008955 UNRESOLVED. Direct purified FtsW and RodA work supports the chemistry in characterized members, including different functional subfamilies; the term is not exclusive to SF2. An exhaustive catalytic assignment to all PTHR30474 members, including SpoVE, is not established here. Use verified SF2 membership together with independent polymerase and division-role evidence for a divisome selector, not the broad family alone. This uncertainty is about full propagation scope, not a denial of the experimentally supported activities.
ftsi_dd_transpeptidase Role-qualified septal class-B PBP
PANTHER:PTHR30627:SF1
Family 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
The family function has no GO identifier for comparison; prose is not matched.
bacsu_dd_transpeptidase Role-qualified septal class-B PBP
PANTHER:PTHR30627:SF26
Family 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
The family function has no GO identifier for comparison; prose is not matched.
staa8_dd_transpeptidase Role-qualified septal class-B PBP
PANTHER:PTHR30627:SF26
Family 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
The family function has no GO identifier for comparison; prose is not matched.
strt2_dd_transpeptidase Role-qualified septal class-B PBP
PANTHER:PTHR30627:SF26
Family 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
The family function has no GO identifier for comparison; prose is not matched.
bacsu_pbp3_dd_transpeptidase Role-qualified septal class-B PBP
PANTHER:PTHR30627:SF25
Family 		serine-type peptidoglycan D,D-transpeptidase activity
No function ID 		No Function Id
The family function has no GO identifier for comparison; prose is not matched.

Gene-review completeness (9/9 grounded genes reviewed)

3 complete review(s) · 1 with deep research · 0 missing review · 8 reviewed but lacking deep research

Gene Review Complete Deep research
ftsI P0AD68 ✓ 42/48 ✓
ftsW O07639 ✓ 11/13 ✗
ftsW P0ABG4 ✓ 43/44 ✗
ftsW Q5M5I9 ✓ 7/9 ✗
pbp2X Q5M2U8 ✓ ✓ ✗
pbpB Q07868 ✓ ✓ ✗
pbpC P42971 ✓ 13/16 ✗
SAOUHSC_01063 Q2G2C2 ✓ 8/10 ✗
SAOUHSC_01145 Q2FZ94 ✓ ✓ ✗

Details

Context
bacteriaNCBITaxon:2
FtsW-bPBP septal polymerization and D,D crosslinkingBiological Processbacterial_divisome_peptidoglycan_transpeptidation

Two-reaction capacity of the sampled FtsW-bPBP implementation; not all divisome assembly, septal synthesis in every bacterium, or sufficient autonomous cytokinesis. Lipid II availability, localization and upstream activation are boundary conditions.

division septum assemblyGO:0000917 peptidoglycan biosynthetic processGO:0009252
Context
bacteriaNCBITaxon:2

Connections

FtsW produces glycan bearing peptide stems for subsequent or coupled D,D crosslinking. Activation of FtsW and catalysis of crosslinks are separately required; PBP3 can provide the latter in the specified Bacillus conditional route.
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
LC-MS separately establishes crosslinked product from FtsW-generated glycan with active StPBP2x.
When StPBP2x was incubated with StFtsW and Lipid II, we observed an LC-MS peak in the mutanolysin digestions corresponding to the dimeric product
Part 1: FtsW glycan polymerization with compatible bPBP
FtsW glycan polymerization with compatible bPBPReactionftsw_glycan_polymerization
Variant set: compatible_polymerization_realizers [Realizer] (One Or More)
ecoli FtsW with compatible bPBPReactionecoli_polymerization_realizer
Context
Escherichia coli K-12NCBITaxon:83333

Annotons

Partner-supported FtsW glycan polymerization
ftsw_glycosyltransferase
Participant: Protein Complex: ecoli compatible FtsW-bPBP synthesis unit
Protein Complex:
ecoli compatible FtsW-bPBP synthesis unit
Active units:
FtsW polymerase
Participant: Family: Verified septal FtsW
Family:
Verified septal FtsWPANTHER:PTHR30474:SF2
Representative Members: P0ABG4UniProtKB:P0ABG4
Required Function:
peptidoglycan glycosyltransferase activityGO:0008955
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: catalytic glycan polymerization
Function:
peptidoglycan glycosyltransferase activityGO:0008955
PMID:33495624
A two-track model for the spatiotemporal coordination of bacterial septal cell wall synthesis revealed by single-molecule imaging of FtsW.
FtsW polymerizes lipid-II-derived glycans at the inner-membrane division site as the SEDS catalytic partner of FtsI/PBP3. Target-specific selective-inactivation and septal glycan-labeling experiments in E. coli support its physiological polymerase role, while purified ortholog complexes establish the cognate-bPBP dependence. This core excludes the separate in-vitro lipid-II translocation capacity.
Combined with the recent evidence that purified FtsW possesses PGTase activity5, our results in live E.coli cells strongly support the notion that FtsW is an essential septal PGTase in vivo.
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
FtsW polymerizes lipid-II-derived glycans at the inner-membrane division site as the SEDS catalytic partner of FtsI/PBP3. Target-specific selective-inactivation and septal glycan-labeling experiments in E. coli support its physiological polymerase role, while purified ortholog complexes establish the cognate-bPBP dependence. This core excludes the separate in-vitro lipid-II translocation capacity.
We conclude that FtsW is a peptidoglycan polymerase that requires divalent cations and the presence of a bPBP for activity.
PMID:9603865
FtsI and FtsW are localized to the septum in Escherichia coli.
FtsW polymerizes lipid-II-derived glycans at the inner-membrane division site as the SEDS catalytic partner of FtsI/PBP3. Target-specific selective-inactivation and septal glycan-labeling experiments in E. coli support its physiological polymerase role, while purified ortholog complexes establish the cognate-bPBP dependence. This core excludes the separate in-vitro lipid-II translocation capacity.
FtsW, another essential cell division protein, was also localized to the septum.
Compatible structural bPBP partner
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF1
Representative Members: P0AD68UniProtKB:P0AD68
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: compatible FtsW activation/structural partner
PMID:20847002
The integral membrane FtsW protein and peptidoglycan synthase PBP3 form a subcomplex in Escherichia coli.
FtsI cross-links peptidoglycan peptide stems at the division septum through serine-dependent D,D-transpeptidation, paired with FtsW glycan polymerization. E. coli cellular evidence supports septal cross-linking; soluble G57-V577 PBP3 aminolysis assays support the acyl-transfer chemistry but do not reconstitute the complete natural septal reaction. The catalytic region acts on the periplasmic face of the inner membrane.
These proteins are able to form a discrete complex independently of the other cell-division proteins.
Presence and compatible interface required; D,D catalytic competence is NOT required for this role. No independent polymerase activity attributed to this subunit. Purified direct activation is established for the S. aureus and S. thermophilus constructs; the E. coli and B. subtilis assignments combine native complex/role evidence with comparative biochemistry.

Function

peptidoglycan glycosyltransferase activityGO:0008955
Substrates: lipid II
Products: peptidoglycan glycan strand bearing peptide stems

Locations

plasma membraneGO:0005886

FtsW catalyzes glycan polymerization in a partner-supported synthesis unit. The bPBP supplies a compatible activation interface independently of its D,D catalytic site.

PMID:33495624
A two-track model for the spatiotemporal coordination of bacterial septal cell wall synthesis revealed by single-molecule imaging of FtsW.
FtsW polymerizes lipid-II-derived glycans at the inner-membrane division site as the SEDS catalytic partner of FtsI/PBP3. Target-specific selective-inactivation and septal glycan-labeling experiments in E. coli support its physiological polymerase role, while purified ortholog complexes establish the cognate-bPBP dependence. This core excludes the separate in-vitro lipid-II translocation capacity.
Combined with the recent evidence that purified FtsW possesses PGTase activity5, our results in live E.coli cells strongly support the notion that FtsW is an essential septal PGTase in vivo.
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
FtsW polymerizes lipid-II-derived glycans at the inner-membrane division site as the SEDS catalytic partner of FtsI/PBP3. Target-specific selective-inactivation and septal glycan-labeling experiments in E. coli support its physiological polymerase role, while purified ortholog complexes establish the cognate-bPBP dependence. This core excludes the separate in-vitro lipid-II translocation capacity.
We conclude that FtsW is a peptidoglycan polymerase that requires divalent cations and the presence of a bPBP for activity.
PMID:9603865
FtsI and FtsW are localized to the septum in Escherichia coli.
FtsW polymerizes lipid-II-derived glycans at the inner-membrane division site as the SEDS catalytic partner of FtsI/PBP3. Target-specific selective-inactivation and septal glycan-labeling experiments in E. coli support its physiological polymerase role, while purified ortholog complexes establish the cognate-bPBP dependence. This core excludes the separate in-vitro lipid-II translocation capacity.
FtsW, another essential cell division protein, was also localized to the septum.

Assembly-supported activity with FtsW as catalytic unit; this is not an assertion that purified FtsW acts autonomously.

bacsu FtsW with compatible bPBPReactionbacsu_polymerization_realizer

Strain-168 reference proteins; native PY79 dynamics and comparative purified ortholog biochemistry support the activation assignment, not a purified O07639/Q07868 reconstitution.

Context
Bacillus subtilis subsp. subtilis str. 168NCBITaxon:224308

Annotons

Partner-supported FtsW glycan polymerization
bacsu_ftsw_glycosyltransferase
Participant: Protein Complex: bacsu compatible FtsW-bPBP synthesis unit
Protein Complex:
bacsu compatible FtsW-bPBP synthesis unit
Active units:
FtsW polymerase
Participant: Family: Verified septal FtsW
Family:
Verified septal FtsWPANTHER:PTHR30474:SF2
Representative Members: O07639UniProtKB:O07639
Required Function:
peptidoglycan glycosyltransferase activityGO:0008955
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: catalytic glycan polymerization
Function:
peptidoglycan glycosyltransferase activityGO:0008955
PMID:38480901
Peptidoglycan synthesis drives a single population of septal cell wall synthases during division in Bacillus subtilis.
Polymerizes septal peptidoglycan glycan strands as the FtsW catalytic component associated with PBP2B. This strain 168 assignment combines the curated FtsW subfamily with PY79 live-cell synthase dynamics and purified ortholog biochemistry; the latter does not establish an independent purified O07639 assay. The current GO reaction uses a lysine-containing lipid-II template; native Bacillus mDAP-containing stem chemistry is a substrate-specificity caveat to that generic polymerase annotation.
a single population of processively moving PBP2B
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Polymerizes septal peptidoglycan glycan strands as the FtsW catalytic component associated with PBP2B. This strain 168 assignment combines the curated FtsW subfamily with PY79 live-cell synthase dynamics and purified ortholog biochemistry; the latter does not establish an independent purified O07639 assay. The current GO reaction uses a lysine-containing lipid-II template; native Bacillus mDAP-containing stem chemistry is a substrate-specificity caveat to that generic polymerase annotation.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/BACSU/ftsW/ftsW-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Polymerizes septal peptidoglycan glycan strands as the FtsW catalytic component associated with PBP2B. This strain 168 assignment combines the curated FtsW subfamily with PY79 live-cell synthase dynamics and purified ortholog biochemistry; the latter does not establish an independent purified O07639 assay. The current GO reaction uses a lysine-containing lipid-II template; native Bacillus mDAP-containing stem chemistry is a substrate-specificity caveat to that generic polymerase annotation.
O07639, ftsW/ylaO/BSU14850, 403 residues, strain 168. PMID38480901 used PY79-derived HaloTag-FtsW strains (including bAB350), not an untagged 168 enzyme. Its modeling explicitly used O07639; this supports reference mapping, not complete identity of every engineered construct. Purified FtsW polymerase evidence from PMID30692671 concerns S. thermophilus and S. aureus orthologs, not O07639.
Compatible structural bPBP partner
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q07868UniProtKB:Q07868
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: compatible FtsW activation/structural partner
PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.
the essential function of PBP 3, in the absence of biochemically active PBP 2B, lies in its TPase activity
PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
The paper distinguishes catalytic inactivation from depletion of the entire PBP2B protein; the conditional PBP3 route retains the essential physical PBP2B role. It does not directly demonstrate PBP2B-to-FtsW activation in purified strain168 proteins.
even though depletion of the entire protein is lethal
Presence and compatible interface required; D,D catalytic competence is NOT required for this role. No independent polymerase activity attributed to this subunit. Purified direct activation is established for the S. aureus and S. thermophilus constructs; the E. coli and B. subtilis assignments combine native complex/role evidence with comparative biochemistry.

Function

peptidoglycan glycosyltransferase activityGO:0008955
Substrates: lipid II
Products: peptidoglycan glycan strand bearing peptide stems

Locations

plasma membraneGO:0005886

FtsW catalyzes glycan polymerization in a partner-supported synthesis unit. The bPBP supplies a compatible activation interface independently of its D,D catalytic site.

PMID:38480901
Peptidoglycan synthesis drives a single population of septal cell wall synthases during division in Bacillus subtilis.
Polymerizes septal peptidoglycan glycan strands as the FtsW catalytic component associated with PBP2B. This strain 168 assignment combines the curated FtsW subfamily with PY79 live-cell synthase dynamics and purified ortholog biochemistry; the latter does not establish an independent purified O07639 assay. The current GO reaction uses a lysine-containing lipid-II template; native Bacillus mDAP-containing stem chemistry is a substrate-specificity caveat to that generic polymerase annotation.
a single population of processively moving PBP2B
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Polymerizes septal peptidoglycan glycan strands as the FtsW catalytic component associated with PBP2B. This strain 168 assignment combines the curated FtsW subfamily with PY79 live-cell synthase dynamics and purified ortholog biochemistry; the latter does not establish an independent purified O07639 assay. The current GO reaction uses a lysine-containing lipid-II template; native Bacillus mDAP-containing stem chemistry is a substrate-specificity caveat to that generic polymerase annotation.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/BACSU/ftsW/ftsW-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Polymerizes septal peptidoglycan glycan strands as the FtsW catalytic component associated with PBP2B. This strain 168 assignment combines the curated FtsW subfamily with PY79 live-cell synthase dynamics and purified ortholog biochemistry; the latter does not establish an independent purified O07639 assay. The current GO reaction uses a lysine-containing lipid-II template; native Bacillus mDAP-containing stem chemistry is a substrate-specificity caveat to that generic polymerase annotation.
O07639, ftsW/ylaO/BSU14850, 403 residues, strain 168. PMID38480901 used PY79-derived HaloTag-FtsW strains (including bAB350), not an untagged 168 enzyme. Its modeling explicitly used O07639; this supports reference mapping, not complete identity of every engineered construct. Purified FtsW polymerase evidence from PMID30692671 concerns S. thermophilus and S. aureus orthologs, not O07639.

Assembly-supported activity with FtsW as catalytic unit; this is not an assertion that purified FtsW acts autonomously.

staa8 FtsW with compatible bPBPReactionstaa8_polymerization_realizer

NCTC8325-derived FtsW residues 2-408 and PBP1 2-744 were assayed after E. coli expression. RN4220/native imaging findings are separate strain evidence.

Context
Staphylococcus aureus subsp. aureus NCTC 8325NCBITaxon:93061

Annotons

Partner-supported FtsW glycan polymerization
staa8_ftsw_glycosyltransferase
Participant: Protein Complex: staa8 compatible FtsW-bPBP synthesis unit
Protein Complex:
staa8 compatible FtsW-bPBP synthesis unit
Active units:
FtsW polymerase
Participant: Family: Verified septal FtsW
Family:
Verified septal FtsWPANTHER:PTHR30474:SF2
Representative Members: Q2G2C2UniProtKB:Q2G2C2
Required Function:
peptidoglycan glycosyltransferase activityGO:0008955
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: catalytic glycan polymerization
Function:
peptidoglycan glycosyltransferase activityGO:0008955
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Polymerizes lipid-II-derived glycan strands as the catalytic FtsW unit of a complex with PBP1. NCTC8325-derived residues 2–408 were assayed with purified PBP1 and S. aureus lipid II; PBP1 active-site inactivation does not remove its activation of FtsW. The deleted initiator methionine and fusion tags are construct boundaries, not a demonstrated native gene-model error.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/STAA8/SAOUHSC_01063/SAOUHSC_01063-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Polymerizes lipid-II-derived glycan strands as the catalytic FtsW unit of a complex with PBP1. NCTC8325-derived residues 2–408 were assayed with purified PBP1 and S. aureus lipid II; PBP1 active-site inactivation does not remove its activation of FtsW. The deleted initiator methionine and fusion tags are construct boundaries, not a demonstrated native gene-model error.
Q2G2C2, official locus SAOUHSC_01063 without a UniProt primary gene symbol, 408 residues, NCTC8325. PMID30692671 explicitly amplified K2–N408 from NCTC8325 genomic DNA; N-terminal His or His-SUMO-FLAG constructs were expressed in E. coli C43(DE3), including D287A. Native overexpression experiments were RN4220; PMID38480900 imaging used other S. aureus backgrounds, not this strain.
Compatible structural bPBP partner
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q2FZ94UniProtKB:Q2FZ94
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: compatible FtsW activation/structural partner
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Catalyzes class-B-PBP D,D peptide crosslinking in S. aureus peptidoglycan, whose acceptor includes the lysine-associated pentaglycine bridge, and physically activates FtsW. NCTC8325 constructs directly establish activation even with PBP1 S314A; the physiological contribution of the catalytic site is independently supported by SH1000/MRSA comparisons and transferred explicitly to this reference protein, not inferred solely from activation or antibiotic binding.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
Presence and compatible interface required; D,D catalytic competence is NOT required for this role. No independent polymerase activity attributed to this subunit. Purified direct activation is established for the S. aureus and S. thermophilus constructs; the E. coli and B. subtilis assignments combine native complex/role evidence with comparative biochemistry.

Function

peptidoglycan glycosyltransferase activityGO:0008955
Substrates: lipid II
Products: peptidoglycan glycan strand bearing peptide stems

Locations

plasma membraneGO:0005886

FtsW catalyzes glycan polymerization in a partner-supported synthesis unit. The bPBP supplies a compatible activation interface independently of its D,D catalytic site.

PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Polymerizes lipid-II-derived glycan strands as the catalytic FtsW unit of a complex with PBP1. NCTC8325-derived residues 2–408 were assayed with purified PBP1 and S. aureus lipid II; PBP1 active-site inactivation does not remove its activation of FtsW. The deleted initiator methionine and fusion tags are construct boundaries, not a demonstrated native gene-model error.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/STAA8/SAOUHSC_01063/SAOUHSC_01063-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Polymerizes lipid-II-derived glycan strands as the catalytic FtsW unit of a complex with PBP1. NCTC8325-derived residues 2–408 were assayed with purified PBP1 and S. aureus lipid II; PBP1 active-site inactivation does not remove its activation of FtsW. The deleted initiator methionine and fusion tags are construct boundaries, not a demonstrated native gene-model error.
Q2G2C2, official locus SAOUHSC_01063 without a UniProt primary gene symbol, 408 residues, NCTC8325. PMID30692671 explicitly amplified K2–N408 from NCTC8325 genomic DNA; N-terminal His or His-SUMO-FLAG constructs were expressed in E. coli C43(DE3), including D287A. Native overexpression experiments were RN4220; PMID38480900 imaging used other S. aureus backgrounds, not this strain.

Assembly-supported activity with FtsW as catalytic unit; this is not an assertion that purified FtsW acts autonomously.

strt2 FtsW with compatible bPBPReactionstrt2_polymerization_realizer

LMG18311 constructs: FtsW current residues 6-431 and PBP2x 1-755, expressed in E. coli. The in-vitro reaction used E. faecalis lipid II; exact native bridge chemistry is not inferred.

Context
Streptococcus thermophilus LMG 18311NCBITaxon:264199

Annotons

Partner-supported FtsW glycan polymerization
strt2_ftsw_glycosyltransferase
Participant: Protein Complex: strt2 compatible FtsW-bPBP synthesis unit
Protein Complex:
strt2 compatible FtsW-bPBP synthesis unit
Active units:
FtsW polymerase
Participant: Family: Verified septal FtsW
Family:
Verified septal FtsWPANTHER:PTHR30474:SF2
Representative Members: Q5M5I9UniProtKB:Q5M5I9
Required Function:
peptidoglycan glycosyltransferase activityGO:0008955
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: catalytic glycan polymerization
Function:
peptidoglycan glycosyltransferase activityGO:0008955
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Polymerizes lipid-II-derived glycan chains after activation by a compatible PBP2x transmembrane interface. Direct assay used LMG18311 FtsW current residues 6–431 with affinity tags in E. coli expression; the FtsW active-site mutation abolished polymerization while PBP2x catalytic inactivation did not. The St reaction used E. faecalis lipid II, so it does not alone identify the exact native S. thermophilus acceptor bridge.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/STRT2/ftsW/ftsW-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Polymerizes lipid-II-derived glycan chains after activation by a compatible PBP2x transmembrane interface. Direct assay used LMG18311 FtsW current residues 6–431 with affinity tags in E. coli expression; the FtsW active-site mutation abolished polymerization while PBP2x catalytic inactivation did not. The St reaction used E. faecalis lipid II, so it does not alone identify the exact native S. thermophilus acceptor bridge.
Q5M5I9, ftsW/stu0486, current 431 residues, LMG18311. PMID30692671 calls the construct M1–R426. Supplementary Table 5 primers oAT01/oAT02 align to CP000023.1 CDS 465656..466951 at relative nucleotides 15..1296, encoding current residues 6–431. Paper D292A/L345G map to current D297A/L350G. Current UniProt sequence version 1 dates from 2005; this is a five-residue construct omission, not evidence of a later database extension or proven native start-site error.
Compatible structural bPBP partner
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q5M2U8UniProtKB:Q5M2U8
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
Role: compatible FtsW activation/structural partner
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Catalyzes serine-dependent D,D transpeptidation of peptidoglycan peptide stems. LC-MS detected a crosslinked dimer that disappeared with PBP2x catalytic inactivation. Activity also occurs with polymer produced by SgtB or transpeptidase-dead PBP1a and survives deletion of the PBP2x transmembrane segment; therefore crosslink catalysis is not an activity supplied only by an inseparable FtsW–PBP2x complex. The assay used E. faecalis substrate and does not fix the exact native S. thermophilus bridge chemistry.
Catalytic inactivation of StPBP2x led to the disappearance of this peak
Presence and compatible interface required; D,D catalytic competence is NOT required for this role. No independent polymerase activity attributed to this subunit. Purified direct activation is established for the S. aureus and S. thermophilus constructs; the E. coli and B. subtilis assignments combine native complex/role evidence with comparative biochemistry.

Function

peptidoglycan glycosyltransferase activityGO:0008955
Substrates: lipid II
Products: peptidoglycan glycan strand bearing peptide stems

Locations

plasma membraneGO:0005886

FtsW catalyzes glycan polymerization in a partner-supported synthesis unit. The bPBP supplies a compatible activation interface independently of its D,D catalytic site.

PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Polymerizes lipid-II-derived glycan chains after activation by a compatible PBP2x transmembrane interface. Direct assay used LMG18311 FtsW current residues 6–431 with affinity tags in E. coli expression; the FtsW active-site mutation abolished polymerization while PBP2x catalytic inactivation did not. The St reaction used E. faecalis lipid II, so it does not alone identify the exact native S. thermophilus acceptor bridge.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/STRT2/ftsW/ftsW-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Polymerizes lipid-II-derived glycan chains after activation by a compatible PBP2x transmembrane interface. Direct assay used LMG18311 FtsW current residues 6–431 with affinity tags in E. coli expression; the FtsW active-site mutation abolished polymerization while PBP2x catalytic inactivation did not. The St reaction used E. faecalis lipid II, so it does not alone identify the exact native S. thermophilus acceptor bridge.
Q5M5I9, ftsW/stu0486, current 431 residues, LMG18311. PMID30692671 calls the construct M1–R426. Supplementary Table 5 primers oAT01/oAT02 align to CP000023.1 CDS 465656..466951 at relative nucleotides 15..1296, encoding current residues 6–431. Paper D292A/L345G map to current D297A/L350G. Current UniProt sequence version 1 dates from 2005; this is a five-residue construct omission, not evidence of a later database extension or proven native start-site error.

Assembly-supported activity with FtsW as catalytic unit; this is not an assertion that purified FtsW acts autonomously.

Part 2: Septal serine-type D,D crosslinking
Septal serine-type D,D crosslinkingReactionftsi_dd_transpeptidation
Variant set: dd_catalytic_realizers [Realizer] (One Or More)
ecoli cognate bPBP crosslinkingReactionecoli_dd_realizer
Context
Escherichia coli K-12NCBITaxon:83333

Annotons

Catalytic septal D,D crosslinking
ftsi_dd_transpeptidase
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF1
Representative Members: P0AD68UniProtKB:P0AD68
Required Function:
serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.

Function

serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine

Locations

plasma membraneGO:0005886

FtsI cross-links peptidoglycan peptide stems at the division septum through serine-dependent D,D-transpeptidation, paired with FtsW glycan polymerization. E. coli cellular evidence supports septal cross-linking; soluble G57-V577 PBP3 aminolysis assays support the acyl-transfer chemistry but do not reconstitute the complete natural septal reaction. The catalytic region acts on the periplasmic face of the inner membrane.

PMID:3531167
Activity of penicillin-binding protein 3 from Escherichia coli.
FtsI cross-links peptidoglycan peptide stems at the division septum through serine-dependent D,D-transpeptidation, paired with FtsW glycan polymerization. E. coli cellular evidence supports septal cross-linking; soluble G57-V577 PBP3 aminolysis assays support the acyl-transfer chemistry but do not reconstitute the complete natural septal reaction. The catalytic region acts on the periplasmic face of the inner membrane.
The peptidoglycan transpeptidase activity of penicillin-binding protein 3 appears to use either nascent or exogenously added UDP-N-acetylmuramyl tripeptide-derived substrates as acceptors.
PMID:2677607
Membrane topology of penicillin-binding protein 3 of Escherichia coli.
FtsI cross-links peptidoglycan peptide stems at the division septum through serine-dependent D,D-transpeptidation, paired with FtsW glycan polymerization. E. coli cellular evidence supports septal cross-linking; soluble G57-V577 PBP3 aminolysis assays support the acyl-transfer chemistry but do not reconstitute the complete natural septal reaction. The catalytic region acts on the periplasmic face of the inner membrane.
PBP3 therefore appeared to have a simple membrane topology with residues 36 to the carboxy-terminus exposed on the periplasmic side of the cytoplasmic membrane.
PMID:9603865
FtsI and FtsW are localized to the septum in Escherichia coli.
FtsI cross-links peptidoglycan peptide stems at the division septum through serine-dependent D,D-transpeptidation, paired with FtsW glycan polymerization. E. coli cellular evidence supports septal cross-linking; soluble G57-V577 PBP3 aminolysis assays support the acyl-transfer chemistry but do not reconstitute the complete natural septal reaction. The catalytic region acts on the periplasmic face of the inner membrane.
The localization of FtsI (PBP3), a penicillin-binding protein specifically required for cell division in Escherichia coli, was investigated by immunofluorescence microscopy and found to localize to the septum.
PMID:20847002
The integral membrane FtsW protein and peptidoglycan synthase PBP3 form a subcomplex in Escherichia coli.
FtsI cross-links peptidoglycan peptide stems at the division septum through serine-dependent D,D-transpeptidation, paired with FtsW glycan polymerization. E. coli cellular evidence supports septal cross-linking; soluble G57-V577 PBP3 aminolysis assays support the acyl-transfer chemistry but do not reconstitute the complete natural septal reaction. The catalytic region acts on the periplasmic face of the inner membrane.
These proteins are able to form a discrete complex independently of the other cell-division proteins.

Catalytic carrier must be active in the evaluated scenario; a protein-presence match alone is insufficient.

bacsu cognate bPBP crosslinkingReactionbacsu_dd_realizer
Context
Bacillus subtilis subsp. subtilis str. 168NCBITaxon:224308

Annotons

Catalytic septal D,D crosslinking
bacsu_dd_transpeptidase
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q07868UniProtKB:Q07868
Required Function:
serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.

Function

serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine

Locations

plasma membraneGO:0005886

Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.

PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.
the essential function of PBP 3, in the absence of biochemically active PBP 2B, lies in its TPase activity
PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.
confirming that the S309 residue is required for penicillin binding
file:genes/BACSU/pbpB/pbpB-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.
Q07868, pbpB/BSU15160, current 713 residues, strain 168. PMID28792086 amplified pbpB from 168 and tested native 168/168CA derivatives plus E. coli membrane expression. The paper discusses a historical translation start offset; current sequence version 3 already has the assayed serine at 309, so no additional +3 offset is applied. PMID38480901 is PY79-derived HaloTag-PBP2B imaging and is explicitly comparative.

Catalytic carrier must be active in the evaluated scenario; a protein-presence match alone is insufficient.

staa8 cognate bPBP crosslinkingReactionstaa8_dd_realizer
Context
Staphylococcus aureus subsp. aureus NCTC 8325NCBITaxon:93061

Annotons

Catalytic septal D,D crosslinking
staa8_dd_transpeptidase
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q2FZ94UniProtKB:Q2FZ94
Required Function:
serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.

Function

serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine

Locations

plasma membraneGO:0005886

Catalyzes class-B-PBP D,D peptide crosslinking in S. aureus peptidoglycan, whose acceptor includes the lysine-associated pentaglycine bridge, and physically activates FtsW. NCTC8325 constructs directly establish activation even with PBP1 S314A; the physiological contribution of the catalytic site is independently supported by SH1000/MRSA comparisons and transferred explicitly to this reference protein, not inferred solely from activation or antibiotic binding.

PMID:35703435
Penicillin-Binding Protein 1 (PBP1) of Staphylococcus aureus Has Multiple Essential Functions in Cell Division.
Catalyzes class-B-PBP D,D peptide crosslinking in S. aureus peptidoglycan, whose acceptor includes the lysine-associated pentaglycine bridge, and physically activates FtsW. NCTC8325 constructs directly establish activation even with PBP1 S314A; the physiological contribution of the catalytic site is independently supported by SH1000/MRSA comparisons and transferred explicitly to this reference protein, not inferred solely from activation or antibiotic binding.
PBP1 TP activity is crucial in MSSA but not in MRSA.
PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Catalyzes class-B-PBP D,D peptide crosslinking in S. aureus peptidoglycan, whose acceptor includes the lysine-associated pentaglycine bridge, and physically activates FtsW. NCTC8325 constructs directly establish activation even with PBP1 S314A; the physiological contribution of the catalytic site is independently supported by SH1000/MRSA comparisons and transferred explicitly to this reference protein, not inferred solely from activation or antibiotic binding.
when we added the cognate divisome bPBP to the FtsW reactions, peptidoglycan polymers were produced
file:genes/STAA8/SAOUHSC_01145/SAOUHSC_01145-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Catalyzes class-B-PBP D,D peptide crosslinking in S. aureus peptidoglycan, whose acceptor includes the lysine-associated pentaglycine bridge, and physically activates FtsW. NCTC8325 constructs directly establish activation even with PBP1 S314A; the physiological contribution of the catalytic site is independently supported by SH1000/MRSA comparisons and transferred explicitly to this reference protein, not inferred solely from activation or antibiotic binding.
Q2FZ94, official locus SAOUHSC_01145 without a UniProt primary gene symbol, 744 residues, NCTC8325. PMID30692671 amplified A2–D744 from NCTC8325 genomic DNA, expressed C-terminal His6 protein in E. coli C43(DE3), and tested S314A as the inactive PBP1 partner. PMID35703435 principally tests SH1000 and derived MRSA backgrounds; those phenotypes are homolog/strain-transfer evidence, not NCTC8325 measurements. PMID38527711 structures39–608 map to Q2FZ94 in frozen UniProt but the cached text is abstract-only.

Catalytic carrier must be active in the evaluated scenario; a protein-presence match alone is insufficient.

strt2 cognate bPBP crosslinkingReactionstrt2_dd_realizer
Context
Streptococcus thermophilus LMG 18311NCBITaxon:264199

Annotons

Catalytic septal D,D crosslinking
strt2_dd_transpeptidase
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q5M2U8UniProtKB:Q5M2U8
Required Function:
serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.

Function

serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine

Locations

plasma membraneGO:0005886

Catalyzes serine-dependent D,D transpeptidation of peptidoglycan peptide stems. LC-MS detected a crosslinked dimer that disappeared with PBP2x catalytic inactivation. Activity also occurs with polymer produced by SgtB or transpeptidase-dead PBP1a and survives deletion of the PBP2x transmembrane segment; therefore crosslink catalysis is not an activity supplied only by an inseparable FtsW–PBP2x complex. The assay used E. faecalis substrate and does not fix the exact native S. thermophilus bridge chemistry.

PMID:30692671
FtsW is a peptidoglycan polymerase that is functional only in complex with its cognate penicillin-binding protein.
Catalyzes serine-dependent D,D transpeptidation of peptidoglycan peptide stems. LC-MS detected a crosslinked dimer that disappeared with PBP2x catalytic inactivation. Activity also occurs with polymer produced by SgtB or transpeptidase-dead PBP1a and survives deletion of the PBP2x transmembrane segment; therefore crosslink catalysis is not an activity supplied only by an inseparable FtsW–PBP2x complex. The assay used E. faecalis substrate and does not fix the exact native S. thermophilus bridge chemistry.
Catalytic inactivation of StPBP2x led to the disappearance of this peak
file:genes/STRT2/pbp2X/pbp2X-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Catalyzes serine-dependent D,D transpeptidation of peptidoglycan peptide stems. LC-MS detected a crosslinked dimer that disappeared with PBP2x catalytic inactivation. Activity also occurs with polymer produced by SgtB or transpeptidase-dead PBP1a and survives deletion of the PBP2x transmembrane segment; therefore crosslink catalysis is not an activity supplied only by an inseparable FtsW–PBP2x complex. The assay used E. faecalis substrate and does not fix the exact native S. thermophilus bridge chemistry.
Q5M2U8, official pbp2X/stu1701, 755 residues, LMG18311. PMID30692671 cloned M1–D755 with a C-terminal His6 tag and S343A catalytic mutant; the soluble G53–D755 construct lacked the transmembrane segment. Full-length constructs were expressed in E. coli C43(DE3), soluble protein in BL21. Direct LC-MS crosslinking used E. faecalis lipid II-derived polymer, not isolated native S. thermophilus lipid II.

Catalytic carrier must be active in the evaluated scenario; a protein-presence match alone is insufficient.

Bacillus PBP3 supplies catalysis while PBP2B remains presentReactionbacsu_pbp3_conditional_realizer

PBP3 supplies catalytic work when PBP2B transpeptidase is disabled, while physical PBP2B remains required. The independent polymerization part still requires FtsW plus its PBP2B structural partner.

Context
Bacillus subtilis subsp. subtilis str. 168NCBITaxon:224308
PBP2B transpeptidase function disabled but structurally functional PBP2B remains present; PBP3 is catalytically active

Annotons

Conditional PBP3 D,D catalytic substitution
bacsu_pbp3_dd_transpeptidase
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF25
Representative Members: P42971UniProtKB:P42971
Required Function:
serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.

Function

serine-type peptidoglycan D,D-transpeptidase activity
Substrates: peptidoglycan glycan strand bearing peptide stems peptidoglycan donor stem terminating in D-Ala-D-Ala amino acceptor on an adjacent stem peptide or its interpeptide bridge
Products: D,D-crosslinked peptidoglycan D-alanine

Locations

plasma membraneGO:0005886

Catalyzes class-B-PBP serine-dependent D,D peptide crosslinking in Bacillus peptidoglycan. PBP3 provides conditional catalytic backup when PBP2B is inactive and contributes to beta-lactam tolerance. The D,D assignment is a mechanistic inference from its enzyme class and active-site-dependent rescue, not a product-resolved PBP3 linkage assay; physical PBP2B remains required.

PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
Catalyzes class-B-PBP serine-dependent D,D peptide crosslinking in Bacillus peptidoglycan. PBP3 provides conditional catalytic backup when PBP2B is inactive and contributes to beta-lactam tolerance. The D,D assignment is a mechanistic inference from its enzyme class and active-site-dependent rescue, not a product-resolved PBP3 linkage assay; physical PBP2B remains required.
the essential function of PBP 3, in the absence of biochemically active PBP 2B, lies in its TPase activity
file:genes/BACSU/pbpC/pbpC-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Catalyzes class-B-PBP serine-dependent D,D peptide crosslinking in Bacillus peptidoglycan. PBP3 provides conditional catalytic backup when PBP2B is inactive and contributes to beta-lactam tolerance. The D,D assignment is a mechanistic inference from its enzyme class and active-site-dependent rescue, not a product-resolved PBP3 linkage assay; physical PBP2B remains required.
P42971, pbpC/ycsM/yzsA/BSU04140, 668 residues, strain 168. PMID28792086 examines168/168CA-derived mutants, PBP3 S410A, and PBP2B S309A. It establishes active-site-dependent compensation and antibiotic tolerance, not direct mass-spectrometric identification of PBP3-generated 4→3 versus3→3 products.

Conditional catalytic compensation supported by active-site-dependent rescue, not a purified PBP3 product-resolved assay. PBP3 is not established as an FtsW activator; this branch asserts no stable three-protein complex.

Essential PBP2B physical role retained
bacsu_pbp2b_structural_retention
Participant: Family: Role-qualified septal class-B PBP
Family:
Role-qualified septal class-B PBPPANTHER:PTHR30627:SF26
Representative Members: Q07868UniProtKB:Q07868
Family membership is necessary but not sufficient: require reviewed role, exact compatible pair, function where specified, and panel context.
PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.
the essential function of PBP 3, in the absence of biochemically active PBP 2B, lies in its TPase activity
file:genes/BACSU/pbpB/pbpB-source-analysis/identity-and-evidence.yaml
Target identity, construct boundaries and evidence scope
Catalyzes serine-dependent D,D peptide crosslinking in septal peptidoglycan and supplies a separable essential physical role in the divisome. Native Bacillus uses mDAP-containing peptidoglycan; the strain 168 S309A/PBP3 experiments establish catalytic compensation, not a product-resolved assay of every linkage or a dispensable PBP2B protein.
Q07868, pbpB/BSU15160, current 713 residues, strain 168. PMID28792086 amplified pbpB from 168 and tested native 168/168CA derivatives plus E. coli membrane expression. The paper discusses a historical translation start offset; current sequence version 3 already has the assayed serine at 309, so no additional +3 offset is applied. PMID38480901 is PY79-derived HaloTag-PBP2B imaging and is explicitly comparative.
PMID:28792086
Functional redundancy of division specific penicillin-binding proteins in Bacillus subtilis.
The paper distinguishes catalytic inactivation from depletion of the entire PBP2B protein; the conditional PBP3 route retains the essential physical PBP2B role. It does not directly demonstrate PBP2B-to-FtsW activation in purified strain168 proteins.
even though depletion of the entire protein is lethal

This is a protein-presence/interface role, not a second D,D catalytic requirement. It does not assert a stable three-protein complex.