title: Acidification of vacuoles is required for autophagic degradation in the yeast, Saccharomyces cerevisiae.
abstract: Acidification inside vacuoles has been shown to play a key role in a number of physiologically important cellular events. We studied the role of vacuolar membrane H(+)-ATPase in the autophagic process of Saccharomyces cerevisiae. Mutants lacking VMA genes which encode their subunits of the vacuolar H(+)-ATPase accumulated autophagic bodies in vacuoles on starvation. vma mutants also had a defect in protein degradation induced by starvation. In vma mutants, the activities of vacuolar proteases were remarkably lower than those of the wild-type. Overexpression of vacuolar proteases did not overcome the defect in the disintegration of autophagic bodies in vma mutant, even the overexpressed proteinase A and proteinase B being substantially localized to the vacuolar compartment and undergoing proper proteolytic maturation. Our results showed that the acidification of vacuoles is not required for the formation and delivery of autophagosomes to vacuoles, but is essential for the disintegration of autophagic bodies.
authors.affiliation: Department of Biology, Graduate School of Arts and Sciences, University of Tokyo.
authors.forename: N
authors.initials: N
authors.lastname: Nakamura
authors.forename: A
authors.initials: A
authors.lastname: Matsuura
authors.forename: Y
authors.initials: Y
authors.lastname: Wada
authors.forename: Y
authors.initials: Y
authors.lastname: Ohsumi
mesh_terms: D016282:Aspartic Acid Endopeptidases / Q000235:genetics / Q000378:metabolism; D001343:Autophagy / Q000502:physiology*; D002268:Carboxypeptidases / Q000235:genetics / Q000378:metabolism; D043402:Cathepsin A; D006863:Hydrogen-Ion Concentration; D016296:Mutagenesis; D017494:Proton Pumps / Q000276:immunology / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000276:immunology* / Q000502:physiology; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases; D014617:Vacuoles / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D016282:Aspartic Acid Endopeptidases; D002268:Carboxypeptidases; D043402:Cathepsin A; D017494:Proton Pumps; D006180:Proton-Translocating ATPases; D012697:Serine Endopeptidases; D025262:Vacuolar Proton-Translocating ATPases; C023302:yeast proteinase B; D029701:Saccharomyces cerevisiae Proteins; C022442:aspergillopepsin II