peptidoglycan-based cell wall

GO:0009274 · Envelope · Envelope layer · Proposed

A protective, load-bearing structure outside the cytoplasmic membrane, built from glycan strands of alternating N-acetylglucosamine and N-acetylmuramic acid cross-linked by short peptides. The resulting murein sacculus surrounds the cell and resists turgor pressure. [DOI:10.1111/j.1574-6976.2007.00094.x]

Synonyms: murein sacculus

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

Components

Component	Type	Part of / acts on	Grounding	Genes	Stoichiometry	Essential	Role
peptidoglycan	Peptidoglycan	part of				ESSENTIAL	Forms the covalently closed, stress-bearing mesh around the cytoplasmic membrane. `DOI:10.1111/j.1574-6976.2007.00094.x` Vollmer et al. review sacculus chemistry and architecture.

Taxonomic distribution

NCBITaxon:2 Bacteria — COMMON: Present in most bacteria; wall-less lineages and L-forms are exceptions. [DOI:10.1111/j.1574-6976.2007.00094.x]

Canonical examples

NCBITaxon:562 Escherichia coli — Canonical Gram-negative murein sacculus model. [DOI:10.1111/j.1574-6976.2007.00094.x]

Functions

cell shape maintenance and resistance to turgor pressure — The cross-linked sacculus bears mechanical stress while permitting growth.
- DOI:10.1111/j.1574-6976.2007.00094.x Structural and physical roles of the sacculus.

Related pathways

Peptidoglycan cytoplasmic synthesis and recycling pathways (WikiPathways:WP5060) — PRODUCED_BY; target taxon NCBITaxon:562.
The E. coli peptidoglycan sacculus is related to the peptidoglycan material produced in WP5060. This is a material-production relation, not equivalence to the entire pathway or a claim about every bacterial wall.
Basis: WP5060 contains a Peptidoglycan Layer product; the structure record describes the E. coli sacculus.. PathwayMech revision: d8ec2b69f7a4c615aecddff80498fef1e1fab0ce.
- DOI:10.1111/j.1574-6976.2007.00094.x Vollmer et al. 2008 describe the peptidoglycan sacculus as cross-linked glycan strands forming the bacterial cell-wall structure. Abstract read through Europe PMC on 2026-10-05.

Mechanism graphs

Lipid II flipping, polymerisation and crosslinking build the sacculus (ASSEMBLY)

The MurJ flippase moves Lipid II from the cytoplasmic leaflet to the extracytoplasmic face of the cytoplasmic membrane, where SEDS-family RodA/FtsW polymerases and penicillin-binding transpeptidases turn Lipid II disaccharide-peptide subunits into crosslinked peptidoglycan strands. The resulting sacculus surrounds the cell as a covalently closed mesh that bears turgor stress.

Subject	Predicate	Object	Evidence
MurJ Lipid II flippase	flips	lipid II	`DOI:10.1126/science.1254522` Sham et al. 2014 showed that E. coli MurJ is needed for Lipid II flipping during peptidoglycan biogenesis.
Lipid II	supplies	lipid II	`DOI:10.1038/s41579-020-0366-3` Egan, Errington and Vollmer 2020 review peptidoglycan synthesis from cytoplasmic lipid-linked precursors through translocation to polymerisation.
RodA/FtsW SEDS peptidoglycan polymerases	polymerise into	alternating GlcNAc-MurNAc glycan strands	`DOI:10.1038/nmicrobiol.2016.253` Emami et al. 2017 identified Bacillus subtilis RodA as a peptidoglycan glycosyltransferase. `DOI:10.1038/s41564-018-0345-x` Taguchi et al. 2019 reconstituted FtsW peptidoglycan polymerase activity in complex with its cognate class B penicillin-binding protein.
penicillin-binding transpeptidases	form	peptide crosslinks	`DOI:10.1038/s41579-020-0366-3` Egan, Errington and Vollmer 2020 review transpeptidation during peptidoglycan synthesis and remodelling.
peptide crosslinks	connect	peptidoglycan	`DOI:10.1111/j.1574-6976.2007.00094.x` Vollmer, Blanot and de Pedro 2008 describe the bacterial sacculus as glycan strands crosslinked by short peptides.
peptidoglycan	resists	resistance to turgor pressure	`DOI:10.1111/j.1574-6976.2007.00094.x` Vollmer, Blanot and de Pedro 2008 review how peptidoglycan architecture gives bacteria a protective, shape-maintaining wall.

Evidence

DOI:10.1111/j.1574-6976.2007.00094.x Peptidoglycan structure and architecture.

Curation history

2026-08-30T19:30:00Z codex · CREATED_RECORD — Added as a literature-backed foundational seed. Identity checked against the 2026-07-01 Gene Ontology release; requires human review.
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.
2026-09-04T01:12:48Z codex · ADD_CAUSAL_GRAPH — Added an ASSEMBLY graph for Lipid II polymerisation, DD-transpeptidase crosslinking, and formation of the turgor-resistant peptidoglycan sacculus, with additional DOI evidence from Egan, Errington and Vollmer 2020.
2026-09-04T02:27:00Z codex · REVISE_CAUSAL_GRAPH — Grounded the Lipid II node to ChEBI, anchored MurJ and RodA/FtsW family nodes to Pfam and InterPro, inserted the MurJ flipping step, and added primary evidence for RodA and FtsW peptidoglycan polymerase activity.
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.

Source: data/structures/envelope/peptidoglycan_based_cell_wall.yaml