title: ESCRT-I components of the endocytic machinery are required for Rim101-dependent ambient pH regulation in the yeast Yarrowia lipolytica.
abstract: Ambient pH signalling involves a cascade of conserved Rim or Pal products in ascomycetous yeasts or filamentous fungi, respectively. Insertional mutagenesis in the yeast Yarrowia lipolytica identified two components of the endosome-associated ESCRT-I complex involved in multivesicular body (MVB) vesicle formation, YlVps28p and YlVps23p. They were shown to be required at alkaline pH, like Rim factors, for transcriptional activation of alkaline-induced genes and repression of acid-induced genes. The constitutively active YlRIM101-1119 allele, which suppresses the pH-signalling defects of Ylrim mutations, also suppresses Ylvps defects in pH response, but not in endocytosis. The contribution of the ESCRT-III component Snf7p could not be assessed due to the essential nature of this component in Y. lipolytica. Unlike Rim factors, YlVps4p, a component of the MVB pathway acting downstream from ESCRT complexes, seems not to be required for the alkaline response. In Y. lipolytica, all vps mutations including those affecting YlVPS4, affected growth at acidic pH, a feature not exhibited by Ylrim mutations. These results suggest that Rim and Vps pathways cooperate in ambient pH signalling and that this relation is conserved across the full range of hemiascomycetous yeasts.
authors.affiliation: Microbiologie et Génétique Moléculaire, Institut National Agronomique Paris-Grignon, Institut National de la Recherche Agronomique UMR1238, Centre National de la Recherche Scientifique UMR2585, 78850 Thiverval-Grignon, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Blanchin-Roland
authors.affiliation: Microbiologie et Génétique Moléculaire, Institut National Agronomique Paris-Grignon, Institut National de la Recherche Agronomique UMR1238, Centre National de la Recherche Scientifique UMR2585, 78850 Thiverval-Grignon, France.
authors.forename: Grégory Da
authors.initials: GD
authors.lastname: Costa
authors.affiliation: Microbiologie et Génétique Moléculaire, Institut National Agronomique Paris-Grignon, Institut National de la Recherche Agronomique UMR1238, Centre National de la Recherche Scientifique UMR2585, 78850 Thiverval-Grignon, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Gaillardin
mesh_terms: D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D056827:Endosomal Sorting Complexes Required for Transport; D011992:Endosomes; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D022161:Transport Vesicles / Q000502:physiology; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*; D025062:Yarrowia / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D056827:Endosomal Sorting Complexes Required for Transport; D005656:Fungal Proteins; D009687:Nuclear Proteins; C083890:SNF7 protein, S cerevisiae; C425333:STP22 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins