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.
| 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. Proposed replacements: ABC-type quaternary ammonium compound transporting activity 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. Proposed replacements: carnitine transmembrane transport choline transport glycine betaine transport 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. Proposed replacements: ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing 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. Proposed replacements: carnitine transmembrane transport 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 |
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Experiment: Reconstitute CbcWV with CbcX, BetX, or CaiX and measure uptake kinetics.
Type: transporter reconstitution
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