title: A genetic screen identifies mutations in the yeast WAR1 gene, linking transcription factor phosphorylation to weak-acid stress adaptation.
abstract: Exposure of the yeast Saccharomyces cerevisiae to weak organic acids such as the food preservatives sorbate, benzoate and propionate leads to the pronounced induction of the plasma membrane ATP-binding cassette (ABC) transporter, Pdr12p. This protein mediates efflux of weak acid anions, which is essential for stress adaptation. Recently, we identified War1p as the dedicated transcriptional regulator required for PDR12 stress induction. Here, we report the results from a genetic screen that led to the isolation of two war1 alleles encoding mutant variants, War1-28p and War1-42p, which are unable to support cell growth in the presence of sorbate. DNA sequencing revealed that War1-28 encodes a truncated form of the transcriptional regulator, and War1-42 carries three clustered mutations near the C-terminal activation domain. Although War1-42 is expressed and properly localized in the nucleus, the War1-42p variant fails to bind the weak-acid-response elements in the PDR12 promoter, as shown by in vivo footprinting. Importantly, in contrast with wild-type War1p, War1-42p is also no longer phosphorylated upon weak-acid challenge, demonstrating that phosphorylation of War1p, its activation and DNA binding are tightly linked processes that are essential for adaptation to weak-acid stress.
authors.affiliation: Medical University Vienna, Max F. Perutz Laboratories, Department of Medical Biochemistry, Campus Vienna Biocenter, Austria.
authors.forename: Christa
authors.initials: C
authors.lastname: Gregori
authors.forename: Bettina
authors.initials: B
authors.lastname: Bauer
authors.forename: Chantal
authors.initials: C
authors.lastname: Schwartz
authors.forename: Angelika
authors.initials: A
authors.lastname: Kren
authors.forename: Christoph
authors.initials: C
authors.lastname: Schüller
authors.forename: Karl
authors.initials: K
authors.lastname: Kuchler
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000096:biosynthesis*; D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D001483:Base Sequence; D004271:DNA, Fungal / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011499:Protein Processing, Post-Translational; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D013011:Sorbic Acid / Q000494:pharmacology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018528:ATP-Binding Cassette Transporters; D004271:DNA, Fungal; C472673:Pdr12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C472674:War1 protein, S cerevisiae; D013011:Sorbic Acid