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A genetic screen identifies mutations in the yeast WAR1 gene, linking transcription factor phosphorylation to weak‐acid stress adaptation
Author(s) -
Gregori Christa,
Bauer Bettina,
Schwartz Chantal,
Kren Angelika,
Schüller Christoph,
Kuchler Karl
Publication year - 2007
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2007.05837.x
Subject(s) - transcription factor , mutant , saccharomyces cerevisiae , biology , gene , phosphorylation , biochemistry , regulator , genetics , mutation , microbiology and biotechnology , chemistry
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, War1‐28 p and War1‐42 p, 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 War1‐42 p 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, War1‐42 p 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.