mlaA (P76506) curation notes

Deep research

just deep-research ECOLI mlaA --provider perplexity was attempted on 2026-10-23 and failed:
"Provider 'perplexity' not available. Available: falcon, openscientist". No deep-research
file was generated; the review is based on cached primary literature and the UniProt record.

Founding Mla paper: mla mutants accumulate PL in the OM outer leaflet PMID:19383799
MlaA is an OM lipoprotein that binds OmpC and OmpF; porin binding alone targets unlipidated MlaA to the OM [PMID:26314242 "We show that the OM lipoprotein MlaA interacts specifically with OmpC and OmpF." ; "This interaction is sufficient to localize MlaA lacking its lipid anchor to the OM."]
Structure: monomeric alpha-helical doughnut in the inner leaflet with an amphipathic pore; selectively removes outer-leaflet PLs; porins not active in transport PMID:29038444
OmpC-MlaA architecture: MlaA entirely within the bilayer, hydrophilic channel, gating hairpin loop PMID:29848551
MlaA-MlaC transient complex (cryo-EM 2.9 Å, PDB 8I8R/8I8X): MlaC docks at the MlaA periplasmic base, juxtaposing channel and MlaC cavity; apo-MlaC binding opens MlaA channel PMID:38092770.
mlaA* gain-of-function allele: PL flow into outer leaflet, LPS increase, vesiculation, death PMID:26929379.
Ekiert 2017 model: "Binding of MlaC to the lipid-bound MlaA-OmpC/OmpF complex results in lipid transfer to the hydrophobic pocket of MlaC" PMID:28388411.
Reconstitution with MlaA donor proteoliposomes, MlaC and MlaFEDB acceptor proteoliposomes PMID:39080293.
Direction: ATP drives retrograde (OM to IM) transport PMID:34873038; anterograde proposals PMID:31235958 are disputed.

Protein binding (3 IPI rows, OmpC/OmpF): REMOVE per protein-binding policy; interactions are real.
Cell outer membrane IEA + RCA: ACCEPT. Membrane IEA: MODIFY -> cell outer membrane.
GO:0120010 IBA + IDA: ACCEPT.
Core MF: contributes_to GO:0120014 phospholipid transfer activity. GO:0120014 is defined as removing
a PL from a membrane, carrying it through the aqueous phase in a hydrophobic pocket and delivering it.
MlaA does the removal/hand-off step but not aqueous carriage (that is MlaC), so enables would overstate;
contributes_to records MlaA as the OM half of the MlaA-MlaC transfer step. GO:0005543 phospholipid
binding was not asserted: there is no direct binding measurement for MlaA (lipid interaction comes from
MD and channel structure). No GO term exists for OM phospholipid extraction by a channel; raised as a
suggested question. No NEW annotation rows added.