AcrAB-TolC multidrug efflux transport complex

cellstructuremech:acrab_tolc_multidrug_efflux_transport_complex · Other · Multiprotein complex · Proposed

An Escherichia coli tripartite multidrug efflux pump complex composed of AcrB inner-membrane RND transporters, AcrA periplasmic adaptor proteins, and the TolC outer-membrane channel that exports xenobiotics across the cell envelope. [ComplexPortal:CPX-4263]

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
Multidrug efflux pump subunit AcrA	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	acrA	6 copies in the E. coli K-12 Complex Portal CPX-4263 entry	ESSENTIAL	Periplasmic adaptor subunit that couples AcrB to TolC in the envelope-spanning AcrAB-TolC pump. `ComplexPortal:CPX-4263` Complex Portal CPX-4263 curates P0AE06/AcrA as six copies in the E. coli K-12 AcrAB-TolC multidrug efflux transport complex. `PDB:5V5S` RCSB maps one PDB:5V5S polymer entity to UniProtKB:P0AE06 in the AcrAB-TolC cryo-EM structure.
Multidrug efflux pump subunit AcrB	Protein	part of	Reviewed label only (reviewed name; no accession asserted)	acrB	3 copies in the E. coli K-12 Complex Portal CPX-4263 entry	ESSENTIAL	Inner-membrane RND transporter subunit that forms the trimeric substrate/proton antiporter core. `ComplexPortal:CPX-4263` Complex Portal CPX-4263 curates P31224/AcrB as three copies in the E. coli K-12 AcrAB-TolC multidrug efflux transport complex. `PDB:5V5S` RCSB maps one PDB:5V5S polymer entity to UniProtKB:P31224 in the AcrAB-TolC cryo-EM structure.
Outer membrane channel protein TolC	Protein	part of	`InterPro:IPR058622`	tolC	3 copies in the E. coli K-12 Complex Portal CPX-4263 entry	ESSENTIAL	Outer-membrane channel subunit that closes the periplasmic AcrA bridge and conducts exported substrates out of the cell envelope. `ComplexPortal:CPX-4263` Complex Portal CPX-4263 curates P02930/TolC as three copies in the E. coli K-12 AcrAB-TolC multidrug efflux transport complex. `PDB:5V5S` RCSB maps one PDB:5V5S polymer entity to UniProtKB:P02930 in the AcrAB-TolC cryo-EM structure. `InterPro:IPR058622` InterPro IPR058622 is the Outer membrane channel protein TolC family entry.

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.

Multidrug efflux pump subunit AcrA

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P0AE06`	Multidrug efflux pump subunit AcrA	acrA	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (1 reference) `UniProtKB:P0AE06` Reviewed Swiss-Prot entry ACRA_ECOLI is the E. coli K-12 AcrA accession and cross-references ComplexPortal:CPX-4263.

Multidrug efflux pump subunit AcrB

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P31224`	Multidrug efflux pump subunit AcrB	acrB	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (1 reference) `UniProtKB:P31224` Reviewed Swiss-Prot entry ACRB_ECOLI is the E. coli K-12 AcrB accession and cross-references ComplexPortal:CPX-4263.

Outer membrane channel protein TolC

Accession	Protein	Gene	Organism	Entry
`UniProtKB:P02930`	Outer membrane protein TolC	tolC	Escherichia coli K-12 (`NCBITaxon:83333`)	REVIEWED
Role and evidence (1 reference) `UniProtKB:P02930` Reviewed Swiss-Prot entry TOLC_ECOLI is the E. coli K-12 TolC accession and cross-references ComplexPortal:CPX-4263.

Source composition assertions

AcrAB-TolC multidrug efflux transport complex (ComplexPortal:CPX-4263)

Escherichia coli (strain K12) (NCBITaxon:83333) · Heterododecamer · ECO:0000353 · retrieved 2026-10-02

Participant	Source type	Source name	Stoichiometry
`UniProtKB:P31224` — Multidrug efflux pump subunit AcrB	protein	acrB	3
`UniProtKB:P0AE06` — Multidrug efflux pump subunit AcrA	protein	acrA	6
`UniProtKB:P02930` — Outer membrane protein TolC	protein	tolC	3

Curator-scoped import: E. coli K-12 AcrAB-TolC source composition for this record. Source evidence: physical interaction evidence. The accession was resolved through the Complex Portal accession endpoint; no equivalence xref was inferred.

Canonical examples

NCBITaxon:83333 Escherichia coli K-12 — Source strain for Complex Portal CPX-4263, which curates the heterododecameric AcrAB-TolC pump with six AcrA, three AcrB, and three TolC subunits. [ComplexPortal:CPX-4263]

Functions

xenobiotic transmembrane transporter activity GO:0042910 — The AcrAB-TolC complex exports xenobiotics across the E. coli cell envelope through the coupled AcrB transporter, AcrA adaptor, and TolC outer-membrane channel.
- GO:0042910 GO:0042910 is the molecular-function term for xenobiotic transmembrane transporter activity.
- ComplexPortal:CPX-4263 Complex Portal cross-references GO:0042910 for the E. coli K-12 AcrAB-TolC multidrug efflux transport complex.

Mechanism graphs

AcrAB-TolC exports xenobiotics across the cell envelope (FUNCTION)

AcrB, AcrA, and TolC form an envelope-spanning efflux pump that exports xenobiotic substrates from E. coli.

Subject	Predicate	Object	Evidence
Multidrug efflux pump subunit AcrB	couples to	Multidrug efflux pump subunit AcrA	`ComplexPortal:CPX-4263` CPX-4263 curates AcrB and AcrA as participants in the E. coli AcrAB-TolC pump.
Multidrug efflux pump subunit AcrA	couples to	Outer membrane channel protein TolC	`ComplexPortal:CPX-4263` CPX-4263 curates AcrA and TolC as participants in the E. coli AcrAB-TolC pump.
AcrAB-TolC multidrug efflux transport complex	enables	xenobiotic transmembrane transporter activity	`ComplexPortal:CPX-4263` Complex Portal cross-references GO:0042910 for the AcrAB-TolC complex.
xenobiotic transmembrane transporter activity	transports	xenobiotic substrate	`PMID:28355133` The PDB:5V5S primary citation structurally studied the AcrAB-TolC multidrug efflux pump.
xenobiotic transmembrane transporter activity	targets	cell exterior	`PDB:5V5S` PDB:5V5S resolves the AcrB, AcrA, and TolC proteins in one three-protein AcrAB-TolC structure.

Discussions

CURATION_TODO (OPEN): Resolve exact source-neutral protein families for AcrA and AcrB before replacing reviewed-label-only component rows. ComplexPortal:CPX-4263, reviewed E. coli UniProt records, and PDB:5V5S exactly identify the AcrA and AcrB proteins, but no InterPro, Pfam, NCBIfam, or GO accession was verified as an exact source-neutral family for either named pump constituent; TolC is already grounded to InterPro:IPR058622.

Evidence

ComplexPortal:CPX-4263 Complex Portal entry for the E. coli K-12 AcrAB-TolC multidrug efflux transport complex.
GO:1990281 Gene Ontology cellular-component parent term for efflux pump complexes.
GO:0042910 Gene Ontology molecular-function term for xenobiotic transmembrane transporter activity.
InterPro:IPR058622 InterPro family entry for Outer membrane channel protein TolC.
UniProtKB:P0AE06 Reviewed E. coli K-12 AcrA UniProtKB entry.
UniProtKB:P31224 Reviewed E. coli K-12 AcrB UniProtKB entry.
UniProtKB:P02930 Reviewed E. coli K-12 TolC UniProtKB entry.
PDB:5V5S RCSB Protein Data Bank entry for a three-protein AcrAB-TolC cryo-EM structure.
PMID:28355133 PubMed identifier for Wang et al. 2017, An allosteric transport mechanism for the AcrAB-TolC multidrug efflux pump.
DOI:10.7554/eLife.24905 DOI for the Wang et al. 2017 AcrAB-TolC structural paper.

Curation history

2026-10-02T06:49:43Z codex · CREATED_RECORD — Scaffolded by scripts/new_record.py
2026-10-02T06:51:34Z codex · EXPANDED_RECORD — Added GO efflux-pump parentage, AcrA/AcrB/TolC component rows with E. coli K-12 reviewed UniProt examples, the exact Complex Portal CPX-4263 source composition, xenobiotic transporter activity, Complex Portal/PDB/PubMed evidence, a compact function graph, and a component-family grounding TODO.
2026-10-02T07:09:23Z codex · REVIEW_FIX — Resolved PR #1905 review issue #1906 by grounding the TolC component to InterPro:IPR058622 and narrowing the open component-family grounding TODO to AcrA and AcrB.

Source: data/structures/other/acrab_tolc_multidrug_efflux_transport_complex.yaml