Feruloyl-CoA synthetase (Fcs; EC 6.2.1.34), the ATP-dependent acid-thiol ligase that initiates catabolism of hydroxycinnamic acids in Pseudomonas putida KT2440. Fcs is a member of the ANL/AMP-binding (acyl-CoA synthetase) enzyme superfamily and activates ferulate (and other hydroxycinnamates such as p-coumarate) to the corresponding coenzyme A thioester, e.g. ferulate + ATP + CoA -> feruloyl-CoA + AMP + diphosphate (with feruloyl-CoA being the first committed intermediate). The feruloyl-CoA produced is subsequently cleaved by the enoyl-CoA hydratase/aldolase Ech (PP_3358) to yield vanillin, which is oxidised by the vanillin dehydrogenase Vdh (PP_3357) to vanillate, funnelling the carbon through protocatechuate into the beta-ketoadipate pathway and central metabolism. The fcs gene is encoded adjacent to vdh and ech in a hydroxycinnamate catabolic gene cluster and acts in the cytoplasm. Fcs is the committed entry (activation) step of the peripheral hydroxycinnamate funnelling pathway, making it central to the ability of P. putida to grow on lignin-derived aromatic monomers.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0006631 fatty acid metabolic process | IEA GO_REF:0000118 | MODIFY | Summary: Over-broad and substrate-incorrect process term derived from a tree-graft over the AMP-binding/acyl-CoA synthetase superfamily. Reason: Fcs acts on ferulate, a hydroxycinnamic (aromatic) acid, not a fatty acid, and the supporting molecular function is feruloyl-CoA synthetase activity for hydroxycinnamate catabolism rather than fatty acid metabolism. The enzyme is the committed entry step of the ferulate/hydroxycinnamate catabolic funnel into the beta-ketoadipate pathway. The correct biological process is ferulate catabolic process (GO:1901067). Proposed replacements: ferulate catabolic process Supporting Evidence: PMID:12764569 physiological function of these structural genes as feruloyl-CoA synthetase (Fcs), enoyl-CoA hydratase/aldolase (Ech), and vanillin dehydrogenase (Vdh), respectively, they were cloned and expressed in Escherichia coli. Recombinant strains harboring fcs and ech were able to transform ferulic acid to vanillin. |
| GO:0031956 medium-chain fatty acid-CoA ligase activity | IEA GO_REF:0000118 | MODIFY | Summary: Imprecise molecular function inherited from the broad acyl-CoA synthetase tree-graft; the physiological substrate is a hydroxycinnamate, not a medium-chain fatty acid. Reason: Although Fcs is correctly placed in the AMP-binding/acyl-CoA synthetase superfamily, the medium-chain fatty acid-CoA ligase term (GO:0031956) does not describe its substrate. Fcs activates ferulate (and other hydroxycinnamates) to their CoA thioesters; the precise, EC-supported term trans-feruloyl-CoA synthase activity (GO:0050563) is already annotated and is the appropriate replacement. Plaggenborg et al. (PMID:12764569) directly tested the KT2440 enzyme. Both existing adjudication reports support the aromatic-substrate assignment, but neither a narrow BLAST score advantage nor the PANTHER subfamily label proves the actual graft point was wrong. Proposed replacements: trans-feruloyl-CoA synthase activity Supporting Evidence: file:PSEPK/fcs/fcs-hypotheses/function-hypothesis-go-0031956/openscientist.md Verdict: REFUTED - Wrong subfamily (within-superfamily mis-placement, failure mode 3) PMID:12764569 physiological function of these structural genes as feruloyl-CoA synthetase (Fcs), enoyl-CoA hydratase/aldolase (Ech), and vanillin dehydrogenase (Vdh), respectively, they were cloned and expressed in Escherichia coli. Recombinant strains harboring fcs and ech were able to transform ferulic acid to vanillin. file:PSEPK/fcs/fcs-hypotheses/function-hypothesis-go-0031956/openscientist.md The protein catalyzes the ATP-dependent activation of ferulic acid (and related hydroxycinnamic acids including caffeic acid and *p*-coumaric acid) to feruloyl-CoA file:PSEPK/fcs/fcs-hypotheses/function-hypothesis-go-0031956/falcon.md **Reaction catalyzed:** Ferulic acid + CoA + ATP → Feruloyl-CoA + AMP + PPi |
| GO:0050563 trans-feruloyl-CoA synthase activity | IEA GO_REF:0000003 | ACCEPT | Summary: Correct core molecular function, mapped from EC 6.2.1.34, matching the UniProt name and the gene's role in ferulate activation. Reason: This is the precise, EC-based annotation for feruloyl-CoA synthetase (ATP + CoA + trans-ferulate -> feruloyl-CoA + AMP + diphosphate). It is consistent with the protein name, the AMP-binding/ANL domain architecture, and pathway evidence placing Fcs (PP_3356) at the ferulate -> feruloyl-CoA activation step in P. putida KT2440. Represents the core function of the gene. Supporting Evidence: file:PSEPK/fcs/fcs-deep-research-falcon.md The UniProt-provided target (Q88HK0) is annotated as **feruloyl-CoA synthetase** (EC **6.2.1.34**) PMID:12764569 physiological function of these structural genes as feruloyl-CoA synthetase (Fcs), enoyl-CoA hydratase/aldolase (Ech), and vanillin dehydrogenase (Vdh), respectively, they were cloned and expressed in Escherichia coli. Recombinant strains harboring fcs and ech were able to transform ferulic acid to vanillin. |
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