Regulation of Phospholipid Biosynthesis in the Yeast Saccharomyces cerevisiae*

Phospholipids are key molecules that contribute to the structural definition of cells and that participate in the regulation of cellular processes. Phospholipid metabolism is a major activity that cells engage in throughout their growth. The yeast, Saccharomyces cerevisiae, serves as a model system in which to study the regulation of phospholipid synthesis and its regulation in eucaryotes. Its membranous organelles, the lipids that comprise these membranes, and the phospholipid biosynthetic pathways that generate these membranes typify eucaryotic cells (1, 2). Many of the structural genes encoding for the phospholipid biosynthetic enzymes have been cloned and characterized (Table I) (3–25), and a number of mutations in these genes have been isolated (3, 7–9, 11–13, 17, 23, 26–33). In addition, a number of the phospholipid biosynthetic enzymes have been purified and studied (Table I) (34–44). The characterization of the wild-type and mutant genes, as well as the gene products encoded by these alleles, has significantly advanced our understanding both of phospholipid biosynthesis and of its regulation. Results from these genetic, molecular, and biochemical studies have shown that the regulation of phospholipid synthesis is a complex, highly coordinated process. The mechanisms that govern this regulation mediate the mRNA and protein levels of the biosynthetic enzymes as well as their activity and localization (1, 2, 45). This review summarizes our current understanding of the regulation of phospholipid metabolism in S. cerevisiae with a particular focus on the regulation of the activity of the biosynthetic enzymes. For more comprehensive reviews, the reader is directed to recent articles by Paltauf et al. (2) and Greenberg and Lopes (45).