RCO1 encodes Rco1 (Resveratrol cleavage oxygenase 1) of Ustilago maydis (Mycosarcoma maydis), a fungal member of the carotenoid cleavage oxygenase (CCO) superfamily and a close functional analog of Neurospora CAO-1. It is a non-heme iron dioxygenase that oxidatively cleaves the interphenyl Calpha-Cbeta double bond of the stilbene phytoalexin resveratrol (and its derivative piceatannol) to yield 3,5-dihydroxybenzaldehyde and 4-hydroxybenzaldehyde. Rco1 is highly substrate-specific and does not act on carotenoids. U. maydis encodes two CCO-family paralogs: Cco1, a genuine beta-carotene cleavage enzyme, and Rco1, the resveratrol/stilbene cleaver reviewed here - the same carotenoid- vs stilbene-cleaver paralog split seen in Neurospora (CAO-2 vs cao-1).
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0010436 carotenoid dioxygenase activity | IBA GO_REF:0000033 | REMOVE | Summary: Phylogenetic (IBA) carotenoid dioxygenase activity. Experimentally refuted: purified Rco1 cleaves resveratrol and piceatannol but has no activity on carotenoids (PMID:21073977). A CCO-family over-propagation identical to the cao-1 case. Reason: Contradicted by direct enzyme assays showing Rco1 is a resveratrol/stilbene cleaver, not a carotenoid enzyme. The correct specific term is GO:7770086 (resveratrol dioxygenase activity, RHEA:73735; go-ontology PR #32332, merged 2026-07-17, live in QuickGO); the general activity is already covered by GO:0016702. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Supporting Evidence: PMID:21073977 Um Rco1 exhibits a high degree of substrate specificity, as suggested by the lack of activity on carotenoids and the other resveratrol-related compounds tested |
| GO:0016121 carotene catabolic process | IBA GO_REF:0000033 | MODIFY | Summary: Phylogenetic (IBA) carotene catabolic process. Wrong substrate class; Rco1 acts in stilbene catabolism (resveratrol/piceatannol cleavage). Reason: Replace with GO:0046272 (stilbene catabolic process), matching the demonstrated activity. Same CCO-family over-propagation as the carotenoid MF term. Propagation Review Root cause: PROPAGATION BAD Failure modes: FUNCTIONAL DIVERGENCE Proposed replacements: stilbene catabolic process Supporting Evidence: PMID:21073977 the phytoalexin resveratrol and its derivative piceatannol |
| GO:0016702 oxidoreductase activity, acting on single donors with incorporation of molecular oxygen, incorporation of two atoms of oxygen | IEA GO_REF:0000002 | ACCEPT | Summary: InterPro-based (IEA) dioxygenase MF term. Correct and consistent with the demonstrated stilbene dioxygenase activity of Rco1. Reason: Accurate general dioxygenase MF; the specific resveratrol-cleavage activity sits under this term. |
Loading supporting content…
Download this section (compressed HTML)Q: U. maydis has the same carotenoid/stilbene paralog split as Neurospora (Cco1/beta-carotene vs Rco1/resveratrol); is the biological role of fungal resveratrol cleavage (detoxification vs competition) shared between the two fungi?
Loading supporting content…
Download this section (compressed HTML)