Curation Notes: tauD1 (A0A0H2MHV8 / VPARA_23370) in Variovorax paradoxus TBEA6
1. Gene & Protein Identity
- UniProt Accession:
A0A0H2MHV8 (A0A0H2MHV8_VARPD, unreviewed TrEMBL, 302 aa, EC 1.14.11.17)
- Gene Symbol / Locus Tag:
tauD1 / VPARA_23370
- Organism: Variovorax paradoxus strain TBEA6 (
NCBITaxon:34073)
- Sequence & Active-Site Architecture:
- Full-length TauD/TfdA-like $\text{Fe(II)}$/$\alpha$-ketoglutarate-dependent dioxygenase domain (
Pfam:PF02668, residues 23–294; InterPro:IPR003819, PANTHER:PTHR30468:SF1) [UniProtKB:A0A0H2MHV8, "FT DOMAIN 23..294"].
- Conserves the canonical mononuclear non-heme $\text{Fe(II)}$ 2-His-1-carboxylate facial triad (
WHTD motif at residues 117–120: His118 and Asp120 in 113-YENSWHTD-120, plus distal His278 in 273-NRSTQHYA-280, corresponding to His99, Asp101, and His255 in E. coli TauD) and the 2-oxoglutarate/sulfonate-binding Arg residues.
2. Pathway Context & Module Linkage
- Existing Reusable Module:
modules/taurine_uptake_and_desulfonation.yaml (MODULE:taurine_uptake_and_desulfonation).
- Complementary Rhizosphere Organosulfonate Module: Complements the $\text{FMNH}_2$-dependent alkanesulfonate monooxygenase
ssuD (VPARA_19220, curated in Tranche 1 and linked to modules/bacterial_alkanesulfonate_uptake_desulfonation.yaml). Together, TauD1 ($\alpha$-ketoglutarate/$\text{Fe(II)}$-dependent dioxygenase) and SsuD/SsuE ($\text{FMNH}_2$-dependent two-component monooxygenase) equip Variovorax paradoxus TBEA6 to mineralize both taurine and diverse aliphatic sulfonates in sulfate-depleted rhizosphere soils [PMID:9287300, "The Escherichia coli tauD gene is required for the utilization of taurine (2-aminoethanesulfonic acid) as a sulfur source and is expressed only under conditions of sulfate starvation."].
3. Review of Existing GOA Annotations
GO:0000908 (taurine dioxygenase activity, IEA) -> ACCEPT: Core catalytic activity (EC 1.14.11.17).
GO:0016706 (2-oxoglutarate-dependent dioxygenase activity, IEA) -> TOO_GENERAL: Direct is_a parent of GO:0000908.
GO:0016491 (oxidoreductase activity, IEA) -> TOO_GENERAL: Broad ancestor of GO:0000908.
GO:0005737 (cytoplasm, IEA) -> MODIFY to GO:0005829 (cytosol) + NEW (IC): Soluble cytosolic enzyme.
- Added
NEW (IC) GO:0005506 (iron ion binding, enables) and GO:0019529 (taurine catabolic process, involved_in): Captures the essential non-heme $\text{Fe(II)}$ cofactor and the biological process missing from GOA.