Functional identification of sterol-4α-methyl oxidase cDNAs from Arabidopsis thaliana by complementation of a yeast erg25 mutant lacking sterol-4α-methyl oxidation

Specific primers derived from both genomic sequence data and EST cDNA sequences were used to polymerase chain reaction amplify two full-length cDNA sequences AtSMO1 and AtSMO2), 801 and 783 bp, respectively, from an Arabidopsis thaliana cDNA library. The predicted proteins show 32 and 29% identity to the ERG25 gene from Saccharomyces cerevisiae which encodes the sterol-4 alpha -methyl oxidase (SMO), a membrane-bound non-heme di-iron oxygenase involved in lipid metabolism. Heterologous expression of AtSMO1 and AtSMO2 in a yeast erg25 ergosterol auxotroph, lacking SMO activity, restored growth and endogenous ergosterol synthesis. These results represent the first functional identification of SMO genes from plants. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.