Genetic characterization of genes encoding enzymes catalyzing addition of phospho-ethanolamine to the glycosylphosphatidylinositol anchor in Saccharomyces cerevisiae.
MPC1/GPI13/YLL031C, one of the genes involved in the addition of phospho-ethanolamine to the glycosylphosphatidylinositol (GPI) anchor core, is an essential gene. Three available temperature-sensitive mutant alleles, mpc1-3, mpc1-4, and mpc1-5, displayed different phenotypes to each other and, correspondingly, these mutants were found to have different mutations in the MPC1 ORF. Temperature-sensitivity of mpc1-5 mutants was suppressed by 5 mM ZnSO(4) and by 5 mM MnCl(2). Multicopy suppressors were isolated from mpc1-5 mutant. Suppressors commonly effective to mpc1-4 and mpc1-5 mutations are PSD1, encoding phosphatidylserine decarboxylase, and ECM33, which were found to suppress the temperature-sensitive phenotype shown by the fsr2-1 and las21delta mutants, those of which have defects in the GPI anchor synthesis. PSD2, encoding another phosphatidylserine decarboxylase that is localized in Golgi/vacuole, was found to be able to serve as a multicopy suppressor of mpc1 and fsr2-1 mutants but not of the las21 delta mutant. In contrast to psd1delta, psd2delta showed a synthetic growth defect with mpc1 mutants but not with fsr2-1 or las21delta. Furthermore, psd1delta psd2delta mpc1 triple mutants did not form colonies on nutrient medium unless ethanolamine was supplied to the medium, whereas psd1delta psd2 delta fsr2-1 or psd1delta psd2 delta las21delta triple mutants grew on nutrient medium without supplementation of ethanolamine. These observations suggest that Mpc1 preferentially utilizes phosphatidylethanolamine produced by Psd2 that is localized in Golgi/vacuole. fsr2-1 dpl1 Delta psd1delta strains showed slower growth than fsr2-1 dpl1delta psd2 delta, suggesting that Fsr2 enzyme depends more on Dpl1 and Psd1 for production of phosphatidylethanolamine. Las21 did not show preference for the metabolic pathway to produce phosphatidylethanolamine.
Toh-e
Akio
A
Department of Biological Sciences, Graduate School of Science, The University of Tokyo Hongo, Japan. toh-e@biol.s.u-tokyo.ac.jp
Oguchi
Tomoko
T
D002262:Carboxy-Lyases / Q000235:genetics / Q000378:metabolism; D004983:Ethanolamines / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000502:physiology; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D017853:Phosphotransferases (Alcohol Group Acceptor); D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature
D004983:Ethanolamines; D005656:Fungal Proteins; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C005448:phosphorylethanolamine; C413542:GPI13 protein, S cerevisiae; D017853:Phosphotransferases (Alcohol Group Acceptor); D002262:Carboxy-Lyases; C022353:phosphatidylserine decarboxylase