Systematic analysis of yeast strains with possible defects in lipid metabolism

Lipids are essential components of all living cells because they are obliga te components of biological membranes, and serve as energy reserves and sec ond messengers. Many but not all genes encoding enzymes involved in fatty a cid, phospholipid, sterol or sphingolipid biosynthesis of the yeast Sacchar omyces cerevisiae have been cloned and gene products have been functionally characterized. Less information is available about genes and gene products governing the transport of lipids between organelles and within membranes or the turnover and degradation of complex lipids. To obtain more insight i nto lipid metabolism, regulation of lipid biosynthesis and the role of lipi ds in organellar membranes, a group of five European laboratories establish ed methods suitable to screen for novel genes of the yeast Saccharomyces ce revisiae involved in these processes. These investigations were performed w ithin EUROFAN (European Function Analysis Network), a European initiative t o identify the functions of unassigned open reading frames that had been de tected during the Yeast Genome Sequencing Project. First, the methods requi red for the complete lipid analysis of yeast cells based on chromatographic techniques were established and standardized. The reliability of these met hods was demonstrated using tester strains with established defects in lipi d metabolism. During these investigations it was demonstrated that differen t wild-type strains, among them FY1679, CEN.PK2-1C and W303, exhibit marked differences in lipid content and lipid composition. Second, several candid ate genes which were assumed to encode proteins involved in lipid metabolis m were selected, based on their homology to genes of known function. Finall y, lipid composition of mutant strains deleted of the respective open readi ng frames was determined. For some genes we found evidence suggesting a pos sible role in lipid metabolism. Copyright (C) 1999 John Wiley si Sons, Ltd.