Non-enzymatic roles for the URE2 glutathione S-transferase in the response of Saccharomyces cerevisiae to arsenic
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ORIGINAL PAPER
Non-enzymatic roles for the URE2 glutathione S-transferase in the response of Saccharomyces cerevisiae to arsenic Tatina T. Todorova · Anna V. Kujumdzieva · Stéphane Vuilleumier
Received: 3 January 2010 / Revised: 30 June 2010 / Accepted: 2 August 2010 / Published online: 26 August 2010 © Springer-Verlag 2010
Abstract The response of Saccharomyces cerevisiae to arsenic involves a large ensemble of genes, many of which are associated with glutathione-related metabolism. The role of the glutathione S-transferase (GST) product of the URE2 gene involved in resistance of S. cerevisiae to a broad range of heavy metals was investigated. Glutathione peroxidase activity, previously reported for the Ure2p protein, was unaVected in cell-free extracts of an ure2 mutant of S. cerevisiae. Glutathione levels in the ure2 mutant were lowered about threefold compared to the isogenic wild-type strain but, as in the wild-type strain, increased 2–2.5-fold upon addition of either arsenate (AsV) or arsenite (AsIII). However, lack of URE2 speciWcally caused sensitivity to arsenite but not to arsenate. The protective role of URE2 against arsenite depended solely on the GSTencoding 3⬘-end portion of the gene. The nitrogen source used for growth was suggested to be an important determinant of arsenite toxicity, in keeping with non-enzymatic roles of the URE2 gene product in GATA-type regulation.
Communicated by Axel Brakhage. Electronic supplementary material The online version of this article (doi:10.1007/s00203-010-0614-4) contains supplementary material, which is available to authorized users. T. T. Todorova · A. V. Kujumdzieva Faculty of Biology, Department of General and Applied Microbiology, SoWa University “St. Kliment Ohridski”, 1164 SoWa, Bulgaria T. T. Todorova · S. Vuilleumier (&) Université de Strasbourg, UMR 7156 CNRS, 28 rue Goethe, 67083 Strasbourg Cédex, France e-mail: [email protected]
Keywords Ure2 · Glutathione S-transferase · GATA regulation · Arsenic detoxiWcation Abbreviations GSTs Glutathione S-transferases NCR Nitrogen catabolite repression GPx Glutathione peroxidase Gdh1 NADPH-dependent glutamate dehydrogenase Gln1 Glutamine synthetase Gdh2 NAD+-dependent glutamate dehydrogenase
Introduction The protein Ure2p of Saccharomyces cerevisiae has been studied in three diVerent aspects: as a precursor of [URE3], the protease-resistant prion-like altered form of Ure2p (Wickner et al. 2000); as a negative regulator of GATAdependent transcription (Cooper 2002); and as a glutathione S-transferase (GST) (Bousset et al. 2001; Choi et al. 1998). The Ure2 protein sequence consists of two distinct regions (see Lian et al. 2006 for a review). Its N-terminal part, from residue 1 to residue 93, constitutes the prioninducing domain responsible for self-propagation of [URE3] aggregates (Masison and Wickner 1995). The C-terminal part of the URE2 gene product (residues 94– 354) is similar in sequence and three-dimensional structure (Bousset et al. 2001; Coschigano and Magasanik 1991) to glutathione S-transferases
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