SsuD (Vapar_2976) in Variovorax paradoxus S110 is a 389-amino-acid cytosolic FMNH2-dependent alkanesulfonate monooxygenase (EC 1.14.14.5; HAMAP rule MF_01229) belonging to the bacterial luciferase-like TIM-barrel superfamily. Paired with an NAD(P)H-dependent FMN reductase (SsuE), it catalyzes the oxygenolytic C-S bond cleavage of aliphatic sulfonates to yield the corresponding aldehyde and inorganic sulfite, mobilizing organosulfonates in rhizosphere soils for bacterial and host plant sulfur nutrition.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0008726 alkanesulfonate monooxygenase activity | IEA GO_REF:0000120 | ACCEPT | Reason: Vapar_2976 (C5CNW9) is a canonical 389-residue FMNH2-dependent alkanesulfonate monooxygenase (EC 1.14.14.5; HAMAP MF_01229, NCBIfam TIGR03565) that catalyzes the oxidative desulfonation of aliphatic sulfonates to yield an aldehyde and sulfite. Supporting Evidence: UniProtKB:C5CNW9 CC -!- FUNCTION: Catalyzes the desulfonation of aliphatic sulfonates. CC {ECO:0000255|HAMAP-Rule:MF_01229}. |
| GO:0016705 oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen | IEA GO_REF:0000002 | TOO GENERAL | Reason: The broad parent term oxidoreductase activity, acting on paired donors, with incorporation or reduction of molecular oxygen (GO:0016705) is true of SsuD but subsumed by the specific child term alkanesulfonate monooxygenase activity (GO:0008726) already accepted on this record. Supporting Evidence: UniProtKB:C5CNW9 DR HAMAP; MF_01229; Alkanesulf_monooxygen; 1. |
| GO:0046306 alkanesulfonate catabolic process | IEA GO_REF:0000118 | ACCEPT | Reason: SsuD (Vapar_2976) catalyzes the committed C-S bond cleavage step in the alkanesulfonate catabolic pathway (GO:0046306) under inorganic sulfate limitation. Supporting Evidence: UniProtKB:C5CNW9 DR PANTHER; PTHR42847; ALKANESULFONATE MONOOXYGENASE; 1. |
| GO:0010181 FMN binding | IC UniProtKB:C5CNW9 | NEW | Reason: Inferred by curator (IC) from alkanesulfonate monooxygenase activity (GO:0008726, HAMAP MF_01229, RHEA:23064), which requires binding of reduced FMN (FMNH2) as cosubstrate for oxygen activation. Supporting Evidence: UniProtKB:C5CNW9 CC -!- CATALYTIC ACTIVITY: CC Reaction=an alkanesulfonate + FMNH2 + O2 = an aldehyde + FMN + sulfite CC + H2O + 2 H(+); Xref=Rhea:RHEA:23064, ChEBI:CHEBI:15377, CC ChEBI:CHEBI:15378, ChEBI:CHEBI:15379, ChEBI:CHEBI:17359, CC ChEBI:CHEBI:17478, ChEBI:CHEBI:57618, ChEBI:CHEBI:58210, CC ChEBI:CHEBI:134249; EC=1.14.14.5; Evidence={ECO:0000255|HAMAP- CC Rule:MF_01229}; |
| GO:0005829 cytosol | IC UniProtKB:C5CNW9 | NEW | Reason: Inferred by curator (IC) because SsuD (Vapar_2976, HAMAP MF_01229) is a soluble intracellular enzyme lacking signal peptides or transmembrane domains that acts on imported alkanesulfonates in the bacterial cytosol. Supporting Evidence: UniProtKB:C5CNW9 CC -!- FUNCTION: Catalyzes the desulfonation of aliphatic sulfonates. CC {ECO:0000255|HAMAP-Rule:MF_01229}. |
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Download this section (compressed HTML)Q: How are the multiple ssuD paralogs across chromosomes 1 and 2 of Variovorax paradoxus S110 differentially regulated in response to plant root exudates and sulfate starvation?
Experiment: Purify recombinant Vapar_2976 (SsuD) with its cognate FMN reductase SsuE and profile substrate specificity across C2-C12 linear alkanesulfonates, MOPS, and plant sulfolipids.
Hypothesis: Vapar_2976 exhibits broad specificity toward medium-chain aliphatic sulfonates and releases bioavailable sulfite under sulfate-limiting rhizosphere conditions.
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