FAD-dependent monooxygenase afoD

UniProtKB accession:  Q5BEJ7

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UniProtKB description:  FAD-dependent monooxygenase; part of the gene cluster that mediates the biosynthesis of asperfuranone, a probable antitumor agent (PubMed:19199437). The polyketide synthase afoG is responsible for producing the 3,5-dimethyloctadienone moiety from acetyl-CoA, three malonyl-CoA, and two S-adenosyl methionines (SAM) (PubMed:19199437). The 3,5-dimethyloctadienone moiety is then loaded onto the SAT domain of afoE and extended with four malonyl-CoA and one SAM, which leads to the formation of 2,4-dihydroxy-6-(5,7-dimethyl-2-oxo-trans-3-trans-5-nonadienyl)-3-methylbenzaldehyde (compound 2) after reductive release and aldol condensation (PubMed:19199437). AfoD is the next enzyme in the biosynthesis sequence and hydroxylates the side chain at the benzylic position of compound 2 (PubMed:19199437). After benzylic hydroxylation, a furan ring is formed after five-member ring hemiacetal formation and water elimination (PubMed:19199437). AfoF and afoC are proposed to oxidize the R-diketone proton and to reduce the unconjugated carbonyl group, respectively, to generate asperfuranone (PubMed:19199437). Since no intermediates could be isolated from afoF and afoC deletants, the sequence of these two enzymes is not fully understood (PubMed:19199437). Moreover, since afoC deletant still produces a small amount of asperfuranone, other endogenous oxidoreductases might catalyze the same reaction with much less efficiency (PubMed:19199437).