YEAST CLK-1 HOMOLOG (COQ7 CAT5) IS A MITOCHONDRIAL PROTEIN IN COENZYME-Q SYNTHESIS/

Mutations in the clk-1 gene result in slower development and increased life span in Caenorhabditis elegans. The Saccharomyces cerevisiae hom ologue COQ7/CAT5 is essential for several metabolic pathways including ubiquinone biosynthesis, respiration, and gluconeogenic gene activati on. We show here that Coq7p/Cat5p is a mitochondrial inner membrane pr otein directly involved in ubiquinone biosynthesis, and that the defec t in gluconeogenic gene activation in coq7/cat5 null mutants is a gene ral consequence of a defect in respiration. These results obtained in the yeast model suggest that the effects on development and life span in C. elegans clk-1 mutants may relate to changes in the amount of ubi quinone, an essential electron transport component and a lipid soluble antioxidant.