divisome complex

GO:1990586 · Division machinery · Multiprotein complex · Proposed

The membrane-associated protein machine that builds the peptidoglycan division septum in FtsZ-dependent bacterial cytokinesis. Membrane-tethered FtsZ filaments organize the division site and help distribute septal synthases; movement during active synthesis is not universally driven by FtsZ treadmilling. [GO:1990586]

Synonyms: Z ring

Part of: GO:0032153 — cell division site (no local record)

UniProt location names: UniProt Consortium, CC BY 4.0. Reference label and route sources.

Components

Component	Type	Part of / acts on	Genes	Essential	Role
FtsZ filaments	Protein	part of	ftsZ	ESSENTIAL	Tubulin homologue whose GTP-dependent filaments form the Z ring and whose treadmilling helps distribute septal synthases; this does not make treadmilling the universal rate-setting motor of active synthesis. `DOI:10.1146/annurev-biophys-121219-081703` McQuillen & Xiao 2020 review FtsZ filament treadmilling and its role in organising the ring.
membrane tethers (FtsA, ZipA/SepF)	Protein	part of	ftsA, zipA, sepF	ESSENTIAL	Anchor FtsZ filaments to the inner membrane. The listed anchors are lineage-dependent alternatives or partners; ESSENTIAL describes the tethering function, not independent essentiality of every listed gene in every lineage. `DOI:10.1146/annurev-biophys-121219-081703` McQuillen & Xiao 2020 describe FtsA and ZipA tethering FtsZ to the membrane. `DOI:10.1111/j.1749-6632.2012.06818.x` Egan & Vollmer 2012 review the septal synthases and the membrane anchoring of FtsZ. `DOI:10.1038/s41467-021-23099-8` Introduction reviews lineage-dependent bacterial FtsZ anchors and overlapping FtsA/SepF functions. Its M. smithii experiments concern a distinct archaeal system, not occurrence of this bacterial peptidoglycan machine.
septal peptidoglycan synthase (FtsW-FtsI)	Protein complex	part of	ftsW, ftsI	ESSENTIAL	Builds the septal cell wall. In the E. coli two-track model, fast FtsZ-dependent movement distributes synthesis-inactive molecules, whereas slow processive movement is coupled to active peptidoglycan synthesis and is independent of FtsZ treadmilling speed. `DOI:10.1146/annurev-biophys-121219-081703` McQuillen & Xiao 2020 review FtsW-FtsI septal synthesis and its coupling to FtsZ dynamics. `DOI:10.1111/j.1749-6632.2012.06818.x` Egan & Vollmer 2012 review the septal synthases and the membrane anchoring of FtsZ. `DOI:10.1038/s41564-020-00853-0` Yang et al. 2021, Results and Discussion: single-molecule tracking and perturbations distinguish fast FtsZ-dependent and slow synthesis-dependent FtsW/FtsI populations in E. coli. Two-track interpretation is a model, not a universal rate law for all bacteria.

Organism-specific protein examples

Named proteins in which each component's role was established, with the organism the evidence comes from. The component above is the taxon-agnostic family; these are the specific entries behind it.

FtsZ filaments

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P0A9A6`	Cell division protein FtsZ	ftsZ	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) The single reviewed UniProtKB entry for gene ftsZ in Escherichia coli K-12, a taxon this record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `PMID:1944597` Bi EF et al. 1991, ‘FtsZ ring structure associated with division in Escherichia coli.’, Nature. ECO:0000269 experimental evidence cited by UniProt for the 'Cytoplasm' localisation of P0A9A6. `PMID:8917533` Ma X et al. 1996, ‘Colocalization of cell division proteins FtsZ and FtsA to cytoskeletal structures in living Escherichia coli cells by using green fluorescent protein.’, Proc Natl Acad Sci U S A. ECO:0000269 experimental evidence cited by UniProt for the 'Cytoplasm' localisation of P0A9A6.

membrane tethers (FtsA, ZipA/SepF)

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P0ABH0`	Cell division protein FtsA	ftsA	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) The single reviewed UniProtKB entry for gene ftsA in Escherichia coli K-12, a taxon this record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `PMID:15752196` Pichoff S et al. 2005, ‘Tethering the Z ring to the membrane through a conserved membrane targeting sequence in FtsA.’, Mol Microbiol. ECO:0000269 experimental evidence cited by UniProt for the 'Cell inner membrane' localisation of P0ABH0. `PMID:2203741` Pla J et al. 1990, ‘The native form of FtsA, a septal protein of Escherichia coli, is located in the cytoplasmic membrane.’, J Bacteriol. ECO:0000269 experimental evidence cited by UniProt for the 'Cell inner membrane' localisation of P0ABH0.
`UniProtKB:P77173`	Cell division protein ZipA	zipA	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) The single reviewed UniProtKB entry for gene zipA in Escherichia coli K-12, a taxon this record names; other reviewed entries for this symbol exist on sub-strain nodes and this is the one at the taxon the record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `PMID:16079137` Stenberg F et al. 2005, ‘Protein complexes of the Escherichia coli cell envelope.’, J Biol Chem. ECO:0000269 experimental evidence cited by UniProt for the 'Cell inner membrane' localisation of P77173. `PMID:9008158` Hale CA et al. 1997, ‘Direct binding of FtsZ to ZipA, an essential component of the septal ring structure that mediates cell division in E. coli.’, Cell. ECO:0000269 experimental evidence cited by UniProt for the 'Cell inner membrane' localisation of P77173.
`UniProtKB:O31728`	Cell division protein SepF	sepF	Bacillus subtilis subsp. subtilis str. 168 (`NCBITaxon:224308`)	REVIEWED
Role and evidence (2 references) The single reviewed UniProtKB entry for gene sepF in Bacillus subtilis subsp. subtilis str. 168, a taxon this record names. Identifier for the component's declared gene symbol; it is not itself evidence that the protein is part of this structure. `PMID:16420366` Hamoen LW et al. 2006, ‘SepF, a novel FtsZ-interacting protein required for a late step in cell division.’, Mol Microbiol. ECO:0000269 experimental evidence cited by UniProt for the 'Cytoplasm' localisation of O31728. `PMID:16796675` Ishikawa S et al. 2006, ‘A new FtsZ-interacting protein, YlmF, complements the activity of FtsA during progression of cell division in Bacillus subtilis.’, Mol Microbiol. ECO:0000269 experimental evidence cited by UniProt for the 'Cytoplasm' localisation of O31728.

septal peptidoglycan synthase (FtsW-FtsI)

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P0ABG4`	Probable peptidoglycan glycosyltransferase FtsW	ftsW	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) E. coli K-12 subunit of the septal FtsW-FtsI synthase component; septal membership is supported by localization experiments independently of PathwayMech membership. `PMID:9603865` Wang et al. 1998 localized both FtsI and FtsW to the E. coli septum by microscopy. Abstract read through Europe PMC; UniProt cites this primary experiment for these entries. `PMID:11807049` Mercer and Weiss 2002 show that septal FtsW is required to recruit FtsI to the division site. Abstract read through Europe PMC.
`UniProtKB:P0AD68`	Peptidoglycan D,D-transpeptidase FtsI	ftsI	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (2 references) E. coli K-12 subunit of the septal FtsW-FtsI synthase component; septal membership is supported by localization experiments independently of PathwayMech membership. `PMID:9603865` Wang et al. 1998 localized both FtsI and FtsW to the E. coli septum by microscopy. Abstract read through Europe PMC; UniProt cites this primary experiment for these entries. `PMID:11807049` Mercer and Weiss 2002 show that septal FtsW is required to recruit FtsI to the division site. Abstract read through Europe PMC.

Taxonomic distribution

NCBITaxon:2 Bacteria — COMMON: FtsZ-dependent peptidoglycan division is widespread in bacteria, with E. coli and B. subtilis as the reference systems here. COMMON is qualitative, not a census of all bacterial taxa. [DOI:10.1146/annurev-biophys-121219-081703]

Canonical examples

NCBITaxon:83333 Escherichia coli K-12 — Reference system for divisome assembly order and FtsZ treadmilling. [DOI:10.1146/annurev-biophys-121219-081703]
NCBITaxon:1423 Bacillus subtilis — Reference Gram-positive divisome. [DOI:10.1146/annurev-biophys-121219-081703]

Functions

cell division GO:0051301
- DOI:10.1146/annurev-biophys-121219-081703 McQuillen & Xiao 2020 review the FtsZ ring as the organiser of bacterial cytokinesis.
division septum assembly GO:0000917
- DOI:10.1146/annurev-biophys-121219-081703 McQuillen & Xiao 2020 describe septal peptidoglycan synthesis directed by the ring.
- DOI:10.1111/j.1749-6632.2012.06818.x Egan & Vollmer 2012 describe septal peptidoglycan synthesis as the output of the divisome.

Related pathways

Peptidoglycan cytoplasmic synthesis and recycling pathways (WikiPathways:WP5060) — PARTICIPATES_IN; target taxon NCBITaxon:562.
The E. coli exemplar uses FtsW-FtsI for septal peptidoglycan synthesis. The link covers this segment of WP5060, not every cytoplasmic or recycling reaction and not archaeal FtsZ division.
Basis: Curated septal-synthase function and verified E. coli protein membership; WP5060 names FtsW and FtsI.. PathwayMech revision: d8ec2b69f7a4c615aecddff80498fef1e1fab0ce.
- PMID:11807049 Mercer and Weiss 2002 show that E. coli FtsW recruits FtsI to division sites and connects this complex to septal peptidoglycan synthesis. Abstract read through Europe PMC on 2026-10-05.

Physical properties

LENGTH: 40-160 UO:0000018 (individual arc-like FtsZ protofilaments in dividing Caulobacter crescentus NA1000 cells, by cryo-electron tomography; range summarized by the cited review, not a universal filament length)
- DOI:10.1146/annurev-biophys-121219-081703 — The filaments were approximately 40–160 nm long and approximately 5 nm in diameter, consistent with the dimensions of single FtsZ protofilaments based on previous calculations and in vitro EM studies ( 93 , 183 ). Verbatim from the open-access full text (PMC8610174).
- DOI:10.1038/sj.emboj.7601895 Results describe predominantly40-120nm filaments, longest about160nm, in the NA1000 pseudo-time course; initial predivisional reconstructions give80-160nm. Overexpressed FtsZG109S filaments can be much longer.
DIAMETER: ~5 UO:0000018 (individual arc-like FtsZ protofilaments in Caulobacter crescentus, by cryo-electron tomography; not whole-ring diameter)
- DOI:10.1146/annurev-biophys-121219-081703 — The filaments were approximately 40–160 nm long and approximately 5 nm in diameter, consistent with the dimensions of single FtsZ protofilaments based on previous calculations and in vitro EM studies ( 93 , 183 ). Verbatim; the same sentence gives filament length and diameter.
- DOI:10.1038/sj.emboj.7601895 Results report approximately5nm diameter for arc-like filaments. Cryo-ECT resolution is anisotropic and individual monomers are not resolved.
TRANSLOCATION_SPEED: 25-30 nm/s (apparent directional movement of FtsZ clusters at midcell in E. coli and B. subtilis)
- DOI:10.1146/annurev-biophys-121219-081703 — In both E. coli and B. subtilis , it was also discovered that FtsZ clusters in the Z-ring exhibited apparent directional movement with a speed of approximately 25–30 nm/s at midcell ( 20 , 239 ) ( Figure 5d ). Verbatim from PMC8610174. The rate is carried in `value` because UO has no nanometre-per-second term, and tagging a speed with UO:0000018 (nanometer) would state the wrong dimension.
OTHER: ~16 UO:0000018 (peak-to-peak separation of inner-membrane and FtsZ density at a constriction in a Caulobacter crescentus cell overexpressing FtsZG109S, by cryo-electron tomography; not Z-ring radial thickness)
- DOI:10.1038/sj.emboj.7601895 Results, Figure6 caption and Methods: a density profile through a constricted region of an FtsZG109S-overexpressing cell has an FtsZ peak16nm inside the inner-membrane peak; an unconstricted NA1000 region is the negative control. This is an experiment-specific spacing, not a universal physiological value.
- DOI:10.1146/annurev-biophys-121219-081703 The review instead summarizes approximately13nm beneath the membrane. The inspected texts do not explain the13-versus16nm difference. The maintained value follows the explicitly defined primary peak-to-peak experiment; the review discrepancy remains unresolved, not silently reconciled.

Mechanism graphs

FtsZ-dependent distribution and synthesis-dependent motion in the E. coli two-track model (FUNCTION)

E. coli model supported by single-molecule tracking and perturbations: fast, synthesis-inactive FtsW/FtsI follows treadmilling FtsZ, whereas slow movement accompanies active septal synthesis independently of FtsZ treadmilling speed. FtsN promotes the active population. This does not assert identical rate coupling in B. subtilis or all bacteria, or a fully resolved molecular coupling mechanism.

Subject	Predicate	Object	Evidence
E. coli FtsA/ZipA membrane tethers	anchors	FtsZ filaments	`DOI:10.1146/annurev-biophys-121219-081703` McQuillen & Xiao 2020: FtsA and ZipA hold FtsZ filaments at the membrane. `DOI:10.1038/s41467-021-23099-8` Introduction describes lineage-dependent bacterial membrane anchors; FtsA, ZipA and SepF are not an obligatory universal three-protein set.
FtsZ filaments	assembles into	FtsZ ring	`DOI:10.1146/annurev-biophys-121219-081703` McQuillen & Xiao 2020 describe filament assembly into the Z ring at midcell.
FtsZ filaments	undergoes	FtsZ treadmilling	`DOI:10.1146/annurev-biophys-121219-081703` Review of bacterial FtsZ dynamics; polymer turnover is distinct from bulk translocation of a fixed polymer.
FtsW-FtsI septal synthase	has population	fast synthesis-inactive FtsW-FtsI population	`DOI:10.1038/s41564-020-00853-0` Results distinguish fast and slow moving populations by tracking and perturbation.
FtsZ treadmilling	drives movement of	fast synthesis-inactive FtsW-FtsI population	`DOI:10.1038/s41564-020-00853-0` Changing FtsZ GTPase activity changes the fast population; inhibiting peptidoglycan synthesis preferentially eliminates the slow population.
FtsW-FtsI septal synthase	has population	slow synthesis-active FtsW-FtsI population	`DOI:10.1038/s41564-020-00853-0` Slow movement depends on active synthesis and not FtsZ treadmilling speed.
fast synthesis-inactive FtsW-FtsI population	can enter	slow synthesis-active FtsW-FtsI population	`DOI:10.1038/s41564-020-00853-0` Results show that FtsN promotes the slow active population; Discussion proposes the transition between tracks.
slow synthesis-active FtsW-FtsI population	carries out	division septum assembly	`DOI:10.1038/s41564-020-00853-0` FtsW glycosyltransferase and FtsI transpeptidase perturbations tie the slow population to septal synthesis.

Discussions

CURATION_TODO (RESOLVED): Which organism- and method-specific measurements describe FtsZ filament dimensions, membrane spacing and Z-ring radial thickness? The cited review gives E. coli fluorescence-based radial estimates and discusses disagreement with cryo-electron tomography; these are not a universal ring thickness. The separate C. crescentus membrane-spacing property now identifies its primary experiment and retains the review/primary discrepancy. A first pass added filament length and ring thickness attributed to McQuillen & Xiao 2020 without reading it; both were removed (#91). Super-resolution measurements of the ring are exactly the kind of figure that varies by method and organism, so they need the paper, not a recollection.

Evidence

DOI:10.1146/annurev-biophys-121219-081703 McQuillen R & Xiao J 2020, 'Insights into the Structure, Function, and Dynamics of the Bacterial Cytokinetic FtsZ-Ring', Annual Review of Biophysics.
DOI:10.1111/j.1749-6632.2012.06818.x Egan AJF & Vollmer W 2012, 'The physiology of bacterial cell division', Annals of the New York Academy of Sciences — independent review of divisome composition and septal synthesis.
DOI:10.1038/s41467-021-23099-8 Scope boundary: archaeal FtsZ/SepF division systems exist, including M. smithii with a pseudomurein wall. Shared FtsZ is not evidence for the bacterial FtsW-FtsI peptidoglycan inventory curated here. Removing the earlier Archaea occurrence row does not assert absence of archaeal divisomes.

Curation history

2026-08-31T03:48:12Z claude · CREATED_RECORD — Drafted from the cited review. Every GO term, taxon id and DOI was resolved against OLS, NCBI Taxonomy and Crossref before writing; evidence notes state what the review says, not a reading of primary literature. Not yet human-reviewed.
2026-08-31T03:54:23Z claude · ADD_CORROBORATION — Added Egan & Vollmer 2012 as an independent second source (#63) and part_of the cell division site (#64).
2026-08-31T06:12:34Z claude · SET_COMPONENT_ROLE — component_role became required (#77) so the constituent/machinery distinction is machine-readable rather than prose. Set per component; ASSOCIATED_MACHINERY only where the protein acts on the already-assembled structure.
2026-08-31T19:43:06Z claude · ADD_PHYSICAL_PROPERTIES — #65: FtsZ filament length and Z-ring thickness from the review's summary of super-resolution measurements; both use OTHER or LENGTH because the enum has no 'ring thickness'.
2026-08-31T19:45:55Z claude · REMOVE_UNSOURCED_PROPERTIES — #91: removed filament and ring dimensions attributed to a review known only by its title.
2026-09-03T00:03:05Z claude · ADD_PHYSICAL_PROPERTIES — #65: added 4 physical properties, each carrying a verbatim quotation from the open-access full text of a paper already cited on the record. #91 had removed properties of this kind because they rested on papers known only by their Crossref title; these were read. The injectisome needle length #65 asks for is deliberately absent: the source says the needle 'protrudes several nanometers' and gives no figure. Uses the evidence slot added to PhysicalProperty in #165.
2026-09-03T00:05:12Z claude · CORRECT_SNIPPET — Corrected 2 snippet(s) that had been completed from inference rather than read. They were copied from a probe whose own output was truncated for display, and the cut-off endings were filled in: 'within the target cell' for 'within the target eukaryotic cells', and 'in vitro studies ( 111 , 117 )' for 'in vitro EM studies ( 93 , 183 )' -- inventing reference numbers a reader could have chased. `just evidence-verify` refused all four before they could be committed.
2026-09-04T01:38:58Z codex · ENHANCE_CAUSAL_GRAPH — Added an explicit FtsZ treadmilling node and descriptions to the divisome graph so its septal-synthase distribution mechanism is fully represented.
2026-09-03T00:10:07Z claude · CORRECT_UNIT — Self-review: the treadmilling speed carried unit UO:0000018 (nanometer) for a value meaning nanometres per second, with the correction only in prose context. The unit is dropped and the rate carried in value, so nothing false is asserted in a structured field.
2026-09-03T06:43:42Z claude · NARROW_DISCUSSION — Open-issue review: the ring_dimensions_unsourced discussion asked for two quantities and #65 sourced one of them, so its prompt overstated what is missing and would have sent a curator after finished work. Narrowed to the half that is still open.
2026-09-03T07:26:45Z claude · RESTORE_RATIONALE — #179/#180: the previous commit replaced this discussion's rationale and moved its posed_date. The rationale recorded that these figures were once fabricated from paper titles and removed in #91 -- the reason the question exists -- and is restored verbatim. The narrowing moves to `notes`, and posed_date returns to when the question was actually raised.
2026-09-08T07:38:58Z uniprot_genes · SEED_PROTEIN_EXAMPLES — #183: added 4 protein example(s) by resolving each of the component's declared gene symbols to the single reviewed UniProtKB entry for that symbol in a taxon this record names, deduplicated by accession. Symbols resolving to more than one reviewed entry were skipped rather than chosen between.
2026-10-05T17:45:01Z codex · ADD_PATHWAY_LINK — Added an evidence-backed, organism-scoped PathwayMech link with a full source commit and explicit relation limits. Added experimentally localized E. coli K-12 FtsW and FtsI component examples verified in UniProtKB.
2026-10-12T06:19:58Z codex · ADDRESS_SAVED_REVIEW — Addressed 20261012T061610Z-divisome-complex-evidence-review: divisome-bacterial-archaeal-scope; divisome-active-synthesis-versus-treadmilling; divisome-dimension-provenance. Corrected evidence scope and mechanism claims using inspected sources. Original history/rationale and posed dates remain intact; source discrepancies are explicitly retained.
2026-10-12T06:25:02Z codex · ADDRESS_ADVERSARIAL_REVIEW — Addressed 20261012T062353Z-divisome-adversarial-anchor-scope F1, a residual acceptance condition under divisome-active-synthesis-versus-treadmilling: restrict the E. coli-specific graph tether node and edge to FtsA/ZipA while preserving the cross-lineage component group and its SepF example.
2026-10-12T06:31:59Z codex · CORRECT_RESOLVED_DISCUSSION_PROMPT — Complete rendered acceptance for 20261012T061610Z-divisome-complex-evidence-review F3: replace the unchanged false premise in the visible resolved-discussion prompt. The template does not display resolution_note. Preserve original rationale, posed date and all previous history; the pre-edit prompt remains in Git and the immutable observation.

Source: data/structures/division_machinery/divisome_complex.yaml