IDENTIFICATION OF A NEW NUCLEAR GENE (CEM1) ENCODING A PROTEIN HOMOLOGOUS TO A BETA-KETO-ACYL SYNTHASE WHICH IS ESSENTIAL FOR MITOCHONDRIALRESPIRATION IN SACCHAROMYCES-CEREVISIAE

We have analysed a new gene, CEM1, from Saccharomyces cerevisiae. Inac tivation of this gene leads to a respiratory-deficient phenotype. The deduced protein sequence shows strong similarities with beta-keto-acyl synthases or condensing enzymes. Typically, enzymes of this class are involved in the synthesis of fatty acids or similar molecules. An ana lysis of the mitochondrial lipids and fatty acids shows no major diffe rence between the wild type and deleted strains, implying that the CEM 1 gene product is not involved in the synthesis of the bulk fatty acid s. Thus it is possible that the CEM1 protein is involved in the synthe sis of a specialized molecule, probably related to a fatty acid, which is essential for mitochondrial respiration.