Abstract
Two Cytochromes P450 (P450) in yeast are involved in the biosynthesis of sterols. Thus, CYP51 and CYP61 catalyzing the reactions of lanosterol 14α-demethylase and sterol Δ22-desaturase, respectively. In Arabidopsis, four CYP710A genes are located on chromosome 2. From sequence comparison, it has been postulated that plant CYP710s could be the functional homologues of CYP61. To examine the possibility, we prepared a yeast strain in which the CYP61 gene was disrupted by insertion of the LEU2 gene. This yeast strain lacks the Δ22-desaturase activity to produce ergosterol from ergosta 5,7-dienol. However, the ergosterol production activity of this CYP61-disruption mutant was not complimented by the transformation with the CYP710A1 gene from Arabidopsis. Recombinant CYP710A proteins prepared using a baculovirus system could not catalyze the Δ22-desaturase reaction to yield stigmasterol fromβ-sitosterol. Physiological substrates for CYP710As are under investigation using cultured cells of the CYP710A gene overexpression.
