The importance of the five phosphoribosyl-pyrophosphate synthetase (Prs) gene products of Saccharomyces cerevisiae in the maintenance of cell integrity and the subcellular localization of Prs1p.
Phosphoribosyl-pyrophosphate synthetase (Prs) catalyses the synthesis of phosphoribosyl pyrophosphate (PRPP), an intermediate in nucleotide metabolism and the biosynthesis of the amino acids histidine and tryptophan. The Saccharomyces cerevisiae genome contains a family of five PRS genes, PRS1-PRS5. Using anti-peptide antisera directed against two different epitopes of Prs1p it was shown that Prs1p localizes to granular cytoplasmic structures. This localization was confirmed by living cell microscopy of strains expressing a functional green fluorescent protein (GFP)-tagged Prs1p. Analysis of Prs1p distribution in conditional secretory-deficient (sec) mutants suggested that the observed distribution of Prs1p is independent of the secretory pathway. Electron microscopy revealed that plasma membrane invaginations and accumulation of cytoplasmic vesicles were more frequent in strains which lack some of the PRS genes than in the wild-type. The fact that Deltaprs1 and Deltaprs3 are hypersensitive to caffeine and unable to recover from exposure to it as judged by the release of alkaline phosphatase points to a possible link between Prs and the maintenance of cell integrity.
Schneiter
Roger
R
Institut für Biochemie und Lebensmittelchemie, Technische Universität Graz, Petersgasse 12/II, A-8010 Graz, Austria2.
Carter
Andrew T
AT
Genetics and Microbiology Dept, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK3.
Hernando
Yolanda
Y
Genetics and Microbiology Dept, Institute of Food Research, Norwich Research Park, Colney, Norwich NR4 7UA, UK3.
Zellnig
Günther
G
Institut für Pflanzenphysiologie, Karl-Franzens Universität, Schubertstrasse 51, A-8010 Graz, Austria4.
Schweizer
Lilian M
LM
Department of Biological Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK1.
Schweizer
Michael
M
Department of Biological Sciences, Heriot-Watt University, Edinburgh EH14 4AS, UK1.
D000469:Alkaline Phosphatase / Q000378:metabolism; D015153:Blotting, Western / Q000379:methods; D002110:Caffeine / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D010641:Phenotype; D010754:Phosphoribosyl Pyrophosphate / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012268:Ribose-Phosphate Pyrophosphokinase / Q000235:genetics* / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*; D013347:Subcellular Fractions / Q000201:enzymology*
D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D002110:Caffeine; D010754:Phosphoribosyl Pyrophosphate; D012268:Ribose-Phosphate Pyrophosphokinase; D000469:Alkaline Phosphatase