Taurine import ATP-binding protein TauB1 (VPARA_03660, A0A0H2MNF8) in Variovorax paradoxus strain TBEA6 is a 262-amino-acid peripheral inner-membrane ATPase subunit (InterPro IPR003439, PANTHER PTHR42788:SF18) of the TauABC ATP-binding cassette (ABC) taurine importer complex. Encoded as the middle gene of the syntenic tauA-tauB1-tauC (VPARA_03650-VPARA_03670) operon on genomic contig JZWI01000003 (consecutive EMBL CDS accessions KLN58254.1-KLN58256.1) immediately between the periplasmic taurine-binding protein tauA (VPARA_03650, KLN58254.1) and the transmembrane permease tauC (VPARA_03670, KLN58256.1), TauB1 contains an ABC nucleotide-binding domain (PROSITE PS50893, Pfam PF00005, residues 6-235) with a conserved Walker A P-loop ATP-binding motif at residues 40-47 (40-GASGCGKT-47) that hydrolyzes ATP to drive active import of taurine across the cytoplasmic membrane.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000166 nucleotide binding | IEA GO_REF:0000104 | TOO GENERAL | Summary: True but uninformative parent molecular function already entailed by the accepted specific child term GO:0005524 (ATP binding). Reason: GO:0000166 (nucleotide binding) is a broad ancestor term that adds no specificity beyond GO:0005524 (ATP binding) already accepted in this review. Supporting Evidence: file:VARPD/tauB1/tauB1-uniprot.txt FT BINDING 40..47 FT /ligand="ATP" FT /ligand_id="ChEBI:CHEBI:30616" FT /evidence="ECO:0000256|PROSITE-ProRule:PRU00434" |
| GO:0005524 ATP binding | IEA GO_REF:0000120 | ACCEPT | Summary: Core nucleotide-binding activity of the ABC ATPase domain (PROSITE PS50893, residues 6-235) anchored by the Walker A motif at residues 40-47 (40-GASGCGKT-47). Reason: TauB1 contains a canonical ABC transporter nucleotide-binding domain (PROSITE PS50893, InterPro IPR003439, residues 6-235) with a conserved Walker A P-loop ATP-binding site at residues 40-47 (40-GASGCGKT-47, PROSITE-ProRule PRU00434). Supporting Evidence: file:VARPD/tauB1/tauB1-uniprot.txt FT BINDING 40..47 FT /ligand="ATP" FT /ligand_id="ChEBI:CHEBI:30616" FT /evidence="ECO:0000256|PROSITE-ProRule:PRU00434" |
| GO:0016887 ATP hydrolysis activity | IEA GO_REF:0000002 | ACCEPT | Summary: Core intrinsic catalytic activity of the TauB1 ATP-coupling subunit, which hydrolyzes ATP to power conformational cycling of the TauC transmembrane permease. Reason: As the nucleotide-binding and hydrolyzing subunit of the TauABC importer (PROSITE PS50893, InterPro IPR003439, PANTHER PTHR42788:SF18), TauB1 catalyzes ATP hydrolysis to drive active import of taurine across the inner membrane (matching the treatment in PSEPK/tauB). Supporting Evidence: file:VARPD/tauB1/tauB1-uniprot.txt FT DOMAIN 6..235 FT /note="ABC transporter" FT /evidence="ECO:0000259|PROSITE:PS50893" PMID:8808933 The TauA protein contained a putative signal peptide for transport into the periplasm; the TauB and TauC proteins showed sequence similarity to ATP-binding proteins and membrane proteins, respectively, of ABC-type transport systems |
| GO:0015734 taurine transmembrane transport | IC PMID:8808933 Identification of sulfate starvation-regulated genes in Esch... | NEW | Summary: Core biological process energized by TauB1 as the ATPase subunit of the TauAB1C taurine importer. Reason: Inferred by curator (IC) because TauB1 belongs to PANTHER PTHR42788:SF18 (TAURINE IMPORT ATP-BINDING PROTEIN TAUB) and is encoded immediately between tauA (VPARA_03650, KLN58254.1) and tauC (VPARA_03670, KLN58256.1) on contig JZWI01000003 to drive taurine transmembrane transport (GO:0015734; PMID:8808933, PMID:10781534). Supporting Evidence: file:VARPD/tauB1/tauB1-uniprot.txt DR PANTHER; PTHR42788:SF18; TAURINE IMPORT ATP-BINDING PROTEIN TAUB; 1. PMID:8808933 We therefore suggest that the proteins encoded by tauABC constitute an uptake system for taurine and that the product of tauD is involved in the oxygenolytic release of sulfite from taurine. |
| GO:0005886 plasma membrane | IC PMID:8808933 Identification of sulfate starvation-regulated genes in Esch... | NEW | Summary: Peripheral inner-membrane localization at the cytoplasmic face of the TauC transmembrane permease. Reason: Inferred by curator (IC) because TauB1 is the ABC ATP-binding subunit (PROSITE PS50893, PANTHER PTHR42788:SF18) that assembles with the integral inner-membrane permease TauC (VPARA_03670) at the cytoplasmic face of the bacterial plasma membrane (GO:0005886; PMID:8808933). Supporting Evidence: file:VARPD/tauB1/tauB1-uniprot.txt FT DOMAIN 6..235 FT /note="ABC transporter" FT /evidence="ECO:0000259|PROSITE:PS50893" PMID:8808933 The TauA protein contained a putative signal peptide for transport into the periplasm; the TauB and TauC proteins showed sequence similarity to ATP-binding proteins and membrane proteins, respectively, of ABC-type transport systems |
| GO:0055052 ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing | IC PMID:8808933 Identification of sulfate starvation-regulated genes in Esch... | NEW | Summary: ATP-coupling subunit of the tripartite TauA-TauB1-TauC ABC taurine importer complex. Reason: Inferred by curator (IC) because TauB1 (VPARA_03660, KLN58255.1) is encoded immediately between the periplasmic binding subunit tauA (VPARA_03650, KLN58254.1) and the transmembrane permease tauC (VPARA_03670, KLN58256.1) on contig JZWI01000003, assembling into the substrate-binding-subunit-containing TauABC importer complex (GO:0055052; PMID:8808933, PMID:10781534). Supporting Evidence: file:VARPD/tauB1/tauB1-uniprot.txt DR EMBL; JZWI01000003; KLN58255.1; -; Genomic_DNA. PMID:8808933 We therefore suggest that the proteins encoded by tauABC constitute an uptake system for taurine and that the product of tauD is involved in the oxygenolytic release of sulfite from taurine. |
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Download this section (compressed HTML)Q: Is TauB1 (VPARA_03660) essential for taurine utilization as a sole sulfur source in Variovorax paradoxus TBEA6, or can paralogous tauB/ssuB ATPases partially substitute?
Suggested experts: Kertesz MA, Leisinger T
Experiment: Construct an in-frame ΞtauB1 (VPARA_03660) deletion mutant in Variovorax paradoxus TBEA6 and assay growth on taurine versus pentanesulfonate and sulfate as sole sulfur sources.
Hypothesis: Deletion of tauB1 abolishes active taurine import via TauAB1C while leaving SsuA2B2C5-mediated alkanesulfonate utilization intact.
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