Endocytosis is required for the growth of vacuolar H(+)-ATPase-defective yeast: identification of six new END genes.
Yeast mutants that are defective in acidification of the lysosome-like vacuole are able to grow at pH 5.5, but not at pH 7. Here, we present evidence that endocytosis is required for this low pH-dependent growth and use this observation to develop a screen for mutants defective in endocytosis. By isolating mutants that cannot grow when they lack the 60-kD vacuolar ATPase subunit (encoded by the VAT2 gene), we isolated a number of vat2-synthetic lethal (Vsl-) mutant strains. Seven of the Vsl- mutants are defective in endocytosis. Four of these mutant strains (end8-1, end9-1, end10-1, and end11-1) show altered uptake of the endocytosed ligand, alpha-factor, and three (end12-1, end12-2, and end13-1) are probably defective in transfer of internalized material to the vacuole. Most of the mutations also confer a strong Ts- growth defect. The mutants defective in uptake of alpha-factor sort newly synthesized vacuolar proteins correctly, while those which may be defective in subsequent transport steps secrete at least a fraction of the newly synthesized soluble vacuolar proteins. The mutations that result in a defect in alpha-factor uptake are not allelic to any of the genes previously shown to encode endocytic functions.
Munn
A L
AL
Department of Biochemistry, Biozentrum of the University of Basel, Switzerland.
Riezman
H
H
D002268:Carboxypeptidases / Q000378:metabolism; D043402:Cathepsin A; D003470:Culture Media; D004705:Endocytosis / Q000235:genetics*; D005800:Genes, Fungal; D005804:Genes, Lethal; D006863:Hydrogen-Ion Concentration; D007546:Isoquinolines / Q000378:metabolism; D000072235:Mating Factor; D009154:Mutation; D010455:Peptides / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature; D014617:Vacuoles / Q000201:enzymology*
D003470:Culture Media; D007546:Isoquinolines; D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; C017475:lucifer yellow; D002268:Carboxypeptidases; D043402:Cathepsin A; C499283:PRC1 protein, S cerevisiae; C022633:serine carboxypeptidase; D006180:Proton-Translocating ATPases