Cardiolipin is not essential for the growth of Saccharomyces cerevisiae on fermentable or non-fermentable carbon sources

Cardiolipin is a unique dimeric phospholipid, which is present throughout the eukaryotic kingdom and is specifically localized in mitochondrial membranes. It is widely believed that mitochondria possess an essential requirement for this phospholipid. To determine whether cardiolipin is essential for yeast growth, we generated a cardiolipin synthase null mutant by disrupting the CLS1 gene (open reading frame YDL142c on chromosome IV) of Saccharomyces cerevisiae. Biochemical analysis of the mutant indicated that it had no cardiolipin synthase activity and no cardiolipin in its membranes. The enzyme phosphatidylglycerolphosphate synthase, which catalyses the committed step of the cardiolipin pathway, remained unaffected in the null mutant. Haploid cells containing the null allele are viable in media containing glucose, galactose or glycerol/ethanol as the sole carbon source, although growth in galactose or glycerol/ethanol is somewhat reduced in the mutant compared with the wild type. These results indicate that cardiolipin is not essential for the growth of S. cerevisiae in fermentable or nonfermentable carbon sources.