betT1 (PA5375) encodes BetT1, one of three betaine/carnitine/choline transporter (BCCT, TC 2.A.15) family secondary transporters of Pseudomonas aeruginosa. It is a multi-pass cytoplasmic membrane protein that takes up choline, apparently by proton symport, with high affinity and low capacity. Activity needs an 18-residue N-terminal segment encoded from a start codon 54 bp upstream of the annotated one; the originally annotated shorter protein is inactive. betT1 lies next to the betIBA choline-oxidation genes, is repressed by BetI and induced by choline. Together with BetT3 and the ABC transporter CbcXWV, BetT1 supplies choline for catabolism to glycine betaine, especially in the first hours after cells meet choline and under low-osmolarity conditions, but BetT1 alone cannot support growth on choline.
The protein sequence of this entry may not correspond to a single real gene product (for example, two neighbouring genes joined into one model, or a truncated model). Read the name, features and annotations of the entry with this in mind.
WRONG START SITE CONFIRMED ORTHOLOG COMPARISONOTHER
The annotated PA5375 ORF (Q9HTI9, 516 aa; also PA14_70980) starts 54 bp downstream of the functional start and lacks 18 N-terminal residues present in close homologs. Expressed from the annotated start, BetT1 does not take up choline in E. coli MKH13; expressed from the upstream start it does. The UniProt sequence therefore represents an inactive truncation of the real protein, and residue numbers in Q9HTI9 are 18 lower than in the active protein. Annotations of the gene are unaffected.
Supported by:
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005275 amine transmembrane transporter activity | IDA PMID:21478341 Roles of three transporters, CbcXWV, BetT1, and BetT3, in Ps... | MODIFY | Summary: PseudoCAP IDA seed of PTN001247333 from choline uptake by BetT1. Reason: The transported substrate is choline, a quaternary ammonium compound; GO places choline transport under quaternary ammonium group transport, not under amine transport. The specific term is GO:0015220. Seed verdict SOUND for the node term. Proposed replacements: choline transmembrane transporter activity Supporting Evidence: file:PSEAE/betT1/betT1-notes.md A clone expressing betT1 from the alternative start site (p betT1 N) was able take up [ 14 C]choline in M63 medium PMID:21478341 the glycine betaine derived from choline taken up by BetT1 and BetT3 |
| GO:0022857 transmembrane transporter activity | IBA GO_REF:0000033 | MODIFY | Summary: PAINT transmembrane transporter IBD at the BCCT family node PTN001247333. Reason: The family-level term is correct and substrate-neutral by design, since BCCT members carry choline, glycine betaine or carnitine. For BetT1 the substrate is established experimentally, so the row is refined to GO:0015220. Propagation Review Root cause: TERM SCOPING PROBLEM Failure modes: GRANULARITY MISMATCH Sources checked: PANTHER:PTN001247333 · PTN001247333 SUPPORTS TRANSFER BCCT family node; seeds transport different quaternary ammonium compounds, so the node correctly stops at transmembrane transporter activity. The IBD stands on E. coli BetT and CaiT and on BetT1 itself. UniProtKB:Q9HTI9 · BetT1 (this gene) SUPPORTS TRANSFER Own experimental grounding; choline uptake shown in E. coli MKH13. Proposed replacements: choline transmembrane transporter activity Supporting Evidence: file:PSEAE/betT1/betT1-notes.md A clone expressing betT1 from the alternative start site (p betT1 N) was able take up [ 14 C]choline in M63 medium |
| GO:0022857 transmembrane transporter activity | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO transmembrane transporter activity from IPR000060 (BCCT). Reason: As for the IBA row; true but general, refined to choline transmembrane transporter activity. Proposed replacements: choline transmembrane transporter activity Supporting Evidence: file:PSEAE/betT1/betT1-uniprot.txt TIGR00842; bcct file:PSEAE/betT1/betT1-notes.md A clone expressing betT1 from the alternative start site (p betT1 N) was able take up [ 14 C]choline in M63 medium |
| GO:0033265 choline binding | IDA PMID:21478341 Roles of three transporters, CbcXWV, BetT1, and BetT3, in Ps... | MARK AS OVER ANNOTATED | Summary: PseudoCAP IDA to choline binding from the same paper. Reason: The paper measures choline uptake, not binding; substrate binding by a transporter is part of its transport activity and is already captured by choline transmembrane transporter activity. Supporting Evidence: file:PSEAE/betT1/betT1-notes.md A clone expressing betT1 from the alternative start site (p betT1 N) was able take up [ 14 C]choline in M63 medium |
| GO:0042426 choline catabolic process | IDA PMID:21478341 Roles of three transporters, CbcXWV, BetT1, and BetT3, in Ps... | MARK AS OVER ANNOTATED | Summary: PseudoCAP IDA to choline catabolism from the lag phase of the deletion mutant on choline. Reason: BetT1 imports choline for catabolism but does not oxidise it; BetA and BetB do. The growth phenotype on choline is an indirect consequence of reduced uptake, already captured by choline transport. Same call as for CbcW (PA5377) from this paper. Supporting Evidence: PMID:21478341 the glycine betaine derived from choline taken up by BetT1 and BetT3 |
| GO:0015837 amine transport | IEA GO_REF:0000108 | MODIFY | Summary: Inferred from the amine transmembrane transporter IDA. Reason: Follows the MF row; the substrate is choline, so the process is choline transport. Proposed replacements: choline transport Supporting Evidence: PMID:21478341 the glycine betaine derived from choline taken up by BetT1 and BetT3 |
| GO:0055085 transmembrane transport | IEA GO_REF:0000108 | KEEP AS NON CORE | Summary: Inferred from transmembrane transporter activity. Reason: True and as precise as GO allows for the process: the substrate is choline, but GO:0015871 choline transport is not a descendant of GO:0055085 (checked in go-basic.obo and QuickGO, 2026-11-06), so replacing this row with it would drop the transmembrane claim, and GO has no choline transmembrane transport process term. The substrate axis is carried by the GO:0015837 row in this review, which is refined to GO:0015871. Kept as non-core rather than refined. Supporting Evidence: PMID:21478341 the glycine betaine derived from choline taken up by BetT1 and BetT3 |
| GO:0005886 plasma membrane | IBA GO_REF:0000033 | ACCEPT | Summary: IBA plasma membrane from the BCCT node, seeded by E. coli BetT, CaiT and BetT-like P0ABD1. Reason: BCCT transporters are multi-pass cytoplasmic membrane proteins; BetT1 has eleven predicted TM helices and takes up choline into the cell. This seed set does not include PseudoCAP rows. Supporting Evidence: file:PSEAE/betT1/betT1-uniprot.txt TIGR00842; bcct |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | ACCEPT | Summary: UniProt subcellular location mapping (cell membrane). Reason: Agrees with the BCCT family location and the uptake activity. Supporting Evidence: file:PSEAE/betT1/betT1-uniprot.txt TIGR00842; bcct |
| GO:0016020 membrane | IEA GO_REF:0000002 | MODIFY | Summary: InterPro2GO membrane from IPR000060. Reason: True but general; the membrane is the cytoplasmic (plasma) membrane, accepted on two rows here. Proposed replacements: plasma membrane Supporting Evidence: file:PSEAE/betT1/betT1-uniprot.txt TIGR00842; bcct |
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