CYTOCHROME-P-450-CATALYZED MONOTERPENOID OXIDATION IN CATMINT (NEPETA-RACEMOSA) AND AVOCADO (PERSEA-AMERICANA) - EVIDENCE FOR RELATED ENZYMES WITH DIFFERENT ACTIVITIES

A cytochrome P-450 present in ripening avocado (Persea americana) frui t mesocarp (CYP71A1) had previously been shown to metabolize the monot erpenoids 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 ana lysis of catmint leaf polypeptides using avocado cyt P-450 antiserum, showed that a closely related gene is expressed in catmint leaves. Cyt ochrome P-450 in catmint microsomes catalysed the specific hydroxylati on of nerol and geraniol at C-10, whereas avocado CYP71A1, in either a vocado microsomes or heterologously expressed in yeast, catalysed 2,3- or 6,7-epoxidation of these substrates. These results suggest that or thologous genes of the CYP71 family are expressed in these two plant s pecies, but catalyse dissimilar reactions with monoterpenoid substrate s.