title: Cytochrome P-450-catalysed monoterpenoid oxidation in catmint (Nepeta racemosa) and avocado (Persea americana); evidence for related enzymes with different activities.
abstract: A cytochrome P-450 present in ripening avocado (Persea americana) fruit mesocarp (CYP71A1) had previously been shown to metabolize the monoterpenoids nerol and geraniol (Hallahan et al. (1992) Plant Physiol. 98, 1290-1297). Using DNA encoding CYP71A1 as a hybridization probe, we have shown by Southern analysis that a related gene is present in the catmint, Nepeta racemosa. RNA blot analysis, together with Western analysis of catmint leaf polypeptides using avocado cyt P-450 antiserum, showed that a closely related gene is expressed in catmint leaves. Cytochrome P-450 in catmint microsomes catalysed the specific hydroxylation of nerol and geraniol at C-10, whereas avocado CYP71A1, in either avocado microsomes or heterologously expressed in yeast, catalysed 2,3- or 6,7-epoxidation of these substrates. These results suggest that orthologous genes of the CYP71 family are expressed in these two plant species, but catalyse dissimilar reactions with monoterpenoid substrates.
authors.affiliation: Biochemistry and Physiology Department, AFRC Institute of Arable Crops Research, Harpenden, Herts, UK.
authors.forename: D L
authors.initials: DL
authors.lastname: Hallahan
authors.forename: S M
authors.initials: SM
authors.lastname: Lau
authors.forename: P A
authors.initials: PA
authors.lastname: Harder
authors.forename: D W
authors.initials: DW
authors.lastname: Smiley
authors.forename: G W
authors.initials: GW
authors.lastname: Dawson
authors.forename: J A
authors.initials: JA
authors.lastname: Pickett
authors.forename: R E
authors.initials: RE
authors.lastname: Christoffersen
authors.forename: D P
authors.initials: DP
authors.lastname: O'Keefe
mesh_terms: D000080462:Acyclic Monoterpenes; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D010084:Oxidation-Reduction; D010944:Plants / Q000201:enzymology / Q000235:genetics*; D013729:Terpenes / Q000378:metabolism*
chemical_list: D000080462:Acyclic Monoterpenes; D013729:Terpenes; D003577:Cytochrome P-450 Enzyme System; C007836:geraniol