This cytochrome P-450 (heme thiolate) enzyme is involved in the biosynthesis of glucosinolates in plants. The enzyme catalyses an N-hydroxylation of the E isomer of ω-(methylsulfanyl)alkanal oximes, forming an aci-nitro intermediate that reacts non-enzymically with glutathione to produce an N-alkyl-thiohydroximate adduct, the committed precursor of glucosinolates. In the absence of a thiol compound, the enzyme is suicidal, probably due to interaction of the reactive aci-nitro intermediate with active site residues.
The enzyme appears in viruses and cellular organisms
This cytochrome P-450 (heme thiolate) enzyme is involved in the biosynthesis of glucosinolates in plants. The enzyme catalyses an N-hydroxylation of the E isomer of omega-(methylsulfanyl)alkanal oximes, forming an aci-nitro intermediate that reacts non-enzymically with glutathione to produce an N-alkyl-thiohydroximate adduct, the committed precursor of glucosinolates. In the absence of a thiol compound, the enzyme is suicidal, probably due to interaction of the reactive aci-nitro intermediate with active site residues.
Substrates: isoform CYP83A1 catalyzes the initial conversion of aldoximes to thiohydroximates in the synthesis of glucosinolates not derived from tryptophan Products: -
aliphatic oximes derived from chain-elongated homologs of methionine are efficiently metabolized by isoform CYP83A1, whereas CYP83B1 metabolizes these substrates with very low efficiency. Aromatic oximes derived from phenylalanine, tryptophan, and tyrosine are metabolized by both enzymes, although CYP83B1 has higher affinity for these substrates than CYP83A1
loss of CYP83A1 function leads to dramatically reduced parasitic growth of the biotrophic powdery mildew fungus Erysiphe cruciferarum on Arabidopsis thaliana. The CYP83A1 mutants support less well the germination and appressorium formation of Erysiphe cruciferarum on the leaf surface and post-penetration conidiophore formation by the fungus. The mutants also lack very-long-chain aldehydes on their leaf surface. When chemically complemented with the C26 aldehyde n-hexacosanal, the mutants can again support appressorium formation. The mutants further accumulate 5-methylthiopentanaldoxime, the potentially toxic substrate of CYP83A1
loss of CYP83A1 function leads to dramatically reduced parasitic growth of the biotrophic powdery mildew fungus Erysiphe cruciferarum on Arabidopsis thaliana
Isolation and expression of glucosinolate synthesis genes CYP83A1 and CYP83B1 in Pak Choi (Brassica rapa L. ssp. chinensis var. communis (N. Tsen & S.H. Lee) Hanelt)
Meenu, R.; Augustine, R.; Majee, M.; Pradhan, A.K.; Bisht, N.C.
Genomic origin, expression differentiation and regulation of multiple genes encoding CYP83A1, a key enzyme for core glucosinolate biosynthesis, from the allotetraploid Brassica juncea
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