cbcW

UniProt ID: Q88R39
Organism: Pseudomonas putida KT2440
Review Status: COMPLETE
Aliases:
PP_0295
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Gene Description

cbcW (PP_0295) encodes the six-pass integral membrane permease subunit of the modular Cbc ABC importer of Pseudomonas putida KT2440. With the CbcV ATPase it forms the shared core that imports choline, glycine betaine or L-carnitine, according to which periplasmic binding protein (CbcX, BetX or CaiX) docks to it. CbcW provides the translocation pathway; it has no substrate specificity of its own.

Existing Annotations Review

GO Term Evidence Action Reason
GO:0005275 amine transmembrane transporter activity
IEA
GO_REF:0000118
MODIFY
Summary: Transport is right but the substrate class is wrong; GO does not place carnitine, glycine betaine or choline transport under amine transport.
Reason: An OLS4 query of the GO hierarchy (cbcW-bioinformatics/RESULTS.md, hierarchicalAncestors, run 2026-11-04) shows that none of the Cbc substrate terms (GO:0015226, GO:1902603, GO:0015879, GO:0031460, GO:0015220), nor GO:0015418 or GO:0015651, sits under GO:0005275 or GO:0015837; carnitine and betaine transport sit under quaternary ammonium group transport (GO:0015697/GO:0015651). This is a lateral mis-placement rather than a true-but-broad ancestor, so the term is replaced by the correct sibling branch instead of being kept as non-core. The genes/human/SLC22A5 review keeps GO:0015837 on a carnitine transporter as correct but general; the difference from that precedent is deliberate and follows the OLS placement. This supersedes the batch-03 TreeGrafter re-review, which removed the row as a qualifier-only correction (PR #5954). The enables qualifier is also wrong for a permease subunit and is recorded as a source defect.
Supporting Evidence:
file:PSEPK/cbcW/cbcW-bioinformatics/RESULTS.md
| GO:0015226 | carnitine transmembrane transporter activity | no | no | yes |
file:PSEPK/cbcW/cbcW-bioinformatics/RESULTS.md
| GO:0015418 | ABC-type quaternary ammonium compound transporting activity | no | no | yes |
PMID:19919675
Quaternary ammonium compounds (QACs), including glycine betaine, choline and carnitine, are found in many microbial environments
GO:0005886 plasma membrane
IEA
GO_REF:0000044
ACCEPT
Summary: CbcW is a multi-pass inner-membrane permease.
Reason: UniProt predicts six transmembrane helices and a cell-membrane location.
Supporting Evidence:
file:PSEPK/cbcW/cbcW-uniprot.txt
FT TRANSMEM 37..62
GO:0015226 carnitine transmembrane transporter activity
IEA
GO_REF:0000118
ACCEPT
Summary: Correct activity of the CaiX-CbcWV complex that CbcW belongs to; the enables qualifier should be contributes_to.
Reason: The carnitine transporter activity is the right term for the complex: CaiX supplies carnitine selectivity and CbcWV the translocation path. The row is kept and the qualifier error recorded as a source defect, the convention used for the CaiX (Q9HTH6) and CbcV rows and for the BenB subunit in genes/ACIAD/benB; the core function records CbcW with contributes_to. This supersedes the batch-03 TreeGrafter re-review, which removed the row as a qualifier correction (PR #5954).
Supporting Evidence:
PMID:19919675
CaiX, a carnitine-specific binding protein, is required for Cbc-mediated uptake of L-carnitine
GO:0015837 amine transport
IEA
GO_REF:0000108
MODIFY
Summary: Derived mechanically from the amine transporter row; the Cbc substrates are not amines in GO.
Reason: Same lateral mis-placement as the GO:0005275 row (OLS4 query in cbcW-bioinformatics/RESULTS.md): carnitine, glycine betaine and choline transport are not under GO:0015837. The transport claim is replaced by the specific process terms already on this gene. The SLC22A5 review's KEEP_AS_NON_CORE for this term on a carnitine transporter differs from this call deliberately, following the OLS placement.
Supporting Evidence:
file:PSEPK/cbcW/cbcW-bioinformatics/RESULTS.md
| GO:1902603 | carnitine transmembrane transport | no | no | yes |
file:PSEPK/cbcW/cbcW-bioinformatics/RESULTS.md
| GO:0015871 | choline transport | no | no | no |
GO:0015871 choline transport
IEA
GO_REF:0000118
ACCEPT
Summary: CbcW participates in CbcX-dependent choline uptake.
Reason: Characterized Pseudomonas CbcWV cores transport choline with CbcX; GO has no transmembrane child for choline transport.
Supporting Evidence:
PMID:19919675
CbcX, which binds choline with a high affinity and betaine with a much lower affinity
file:PSEPK/cbcW/cbcW-deep-research-openscientist.md
CbcW is the transmembrane permease subunit of the Cbc ABC importer
GO:0016020 membrane
IEA
GO_REF:0000120
MODIFY
Summary: Correct but less specific than plasma membrane.
Reason: CbcW is an integral inner-membrane protein; GO:0005886 is already on this gene.
Proposed replacements: plasma membrane
Supporting Evidence:
file:PSEPK/cbcW/cbcW-uniprot.txt
FT TRANSMEM 37..62
GO:0031460 glycine betaine transport
IEA
GO_REF:0000120
ACCEPT
Summary: The shared CbcWV core supports glycine-betaine uptake with a cognate binding protein.
Reason: Pseudomonas Cbc systems transport betaine through the shared core with BetX or CbcX; GO has no transmembrane child for this process.
Supporting Evidence:
PMID:19919675
The core transporter CbcWV also interacts with the carnitine-specific SBP CaiX (K(m), 24 microM) and the betaine-specific SBP BetX (K(m), 0.6 microM).
GO:0043190 ATP-binding cassette (ABC) transporter complex
IEA
GO_REF:0000120
MODIFY
Summary: CbcW is the membrane subunit of a binding-protein-dependent ABC importer.
Reason: The Cbc importer depends on periplasmic binding proteins, which is GO:0055052, an is_a child of this term.
Supporting Evidence:
PMID:19919675
In addition to the core transporter comprised of a transmembrane protein (CbcW) and an ATPase (CbcV), the Cbc transporter system interacts with at least three SBPs
GO:0055085 transmembrane transport
IEA
GO_REF:0000002
MODIFY
Summary: Correct but general.
Reason: GO:1902603 carnitine transmembrane transport is the supported is_a descendant already on this gene.
Supporting Evidence:
PMID:19919675
demonstrating that CaiX was sufficient for, and specific to, carnitine uptake (Table 5).
GO:1902603 carnitine transmembrane transport
IEA
GO_REF:0000118
ACCEPT
Summary: CbcW participates in CaiX-dependent carnitine import.
Reason: The CbcWV core is experimentally required for carnitine uptake in related Pseudomonas systems.
Supporting Evidence:
PMID:19919675
As expected, MKH13 cells coexpressing cbcWV (on pNcbcWV) and caiX (on a pTOK2T derivative) were able to take up carnitine but not choline and betaine

Core Functions

Membrane permease contribution to quaternary-amine uptake by the Cbc ABC complex.

Supporting Evidence:
  • PMID:19919675
    The core transporter CbcWV also interacts with the carnitine-specific SBP CaiX (K(m), 24 microM) and the betaine-specific SBP BetX (K(m), 0.6 microM).

References

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Suggested Questions for Experts

Q: Does KT2440 CbcW alter transport kinetics when paired with different substrate-binding proteins?

Suggested Experiments

Experiment: Reconstitute CbcWV with CbcX, BetX, or CaiX and measure uptake kinetics.

Type: transporter reconstitution

Deep Research

OpenScientist

(cbcW-deep-research-openscientist.md)

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πŸ“š Additional Documentation

Bioinformatics Results

(RESULTS.md)

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πŸ“„ View Raw YAML

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