TSC (Temperature Sensitive Suppressors of the Calcium Sensitivity of CSG2A) Mutants; A Tool to Investigate Sphingolipid metabolism in the Yeast Saccharomyces Cerevisiae

摘要

Sphingolipids are essential components of eucaryotic cell membranes but the basis of this essential nature is not understood. Sphingolipids and their metabolites have been implicated in a wide range of critical cell functions ranging from regulating cellular processes to fulfilling a membrane structural role. Defects in sphingolipid metabolism are a known cause of many diseases. To gain a more clear understanding of sphingolipid homeostasis, a genetic approach to their study was undertaken in the yeast Saccharomyces cerevisiae using the csg2delta mutant. The csg2delta mutant fails to niannosylate sphingolipids and exhibits a Ca2+ sensitive phenotype not seen in wild type cells. Suppressors to the Ca2+ sensitivity of csg2delta possess mutations in genes prior to of the mannosylation step of sphingolipid biosynthesis resulting in decresed synthesis or altered structure of the toxic, unmannosylated intermediate (IPC-C). Identification of these suppressor genes may help elucidate the reactions occurring in sphingolipid synthesis. A collection of csg2delta suppressor mutants was made which possess a secondary ts conditional lethal phenotype to facilitate cloning by complementation. This collection is referred to as the tsc collection or Temperature Sensitive suppressors of the Calcium sensitivity of csg2delta Fifty-nine ts suppressors were isolated which possess mutations in one of 15 genes (tsc1- tsc15).