High impact information on CYP83A1

• The Arabidopsis ref2 mutant is defective in the gene encoding CYP83A1 and shows both phenylpropanoid and glucosinolate phenotypes [1].
• Upon further investigation, ref2 mutants were found to have reduced levels of all aliphatic glucosinolates and increased levels of indole-derived glucosinolates in their leaves [1].
• Characterization of the ref2 mutants showed that they contained reduced levels of a number of phenylpropanoid pathway-derived products: sinapoylmalate in leaves, sinapoylcholine in seeds, and syringyl lignin in stems [1].
• Two of the three transcripts coding for aliphatic glucosinolates (CYP83A1, AOP3) are also expressed at significantly lower levels in Col flowers [2].
• In a detailed analysis of the substrate specificities of the recombinant enzymes heterologously expressed in yeast (Saccharomyces cerevisiae), we show that aliphatic oximes derived from chain-elongated homologs of methionine are efficiently metabolized by CYP83A1, whereas CYP83B1 metabolizes these substrates with very low efficiency [3].

Biological context of CYP83A1

• CYP83A1 and CYP83B1 heterologously expressed in yeast (Saccharomyces cerevisiae) cells show marked differences in their substrate specificity [4].
• Although expression of CYP83A1 under control of its endogenous promoter in the rnt1-1 background does not prevent the auxin excess and indole glucosinolate deficit phenotype caused by the lack of the CYP83B1 gene, ectopic overexpression of CYP83A1 using a 35S promoter rescues the rnt1-1 phenotype [4].
• CYP83A1 is the closest relative to CYP83B1 and shares 63% amino acid sequence identity [4].
• The involvement of two p450 enzymes, CYP83B1 and CYP83A1, in auxin homeostasis and glucosinolate biosynthesis [4].

Associations of CYP83A1 with chemical compounds

• Instead, CYP83A1 catalyzes the initial conversion of aldoximes to thiohydroximates in the synthesis of glucosinolates not derived from tryptophan [4].
• However, indole-3-acetaldoxime has a 50-fold higher affinity toward CYP83B1 than toward CYP83A1 [4].
• The ability of CYP83A1 to metabolize aromatic oximes, albeit at small levels, explains the presence of indole glucosinolates at various levels in different developmental stages of the CYP83B1 knockout mutant, rnt1-1 [3].

References