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Alterations in the Activity of the Yeast Peroxiredoxin Tsa1 Upon Modification by Alkylating Agents
Author(s) -
Brown Haley Ann,
Justice Samantha L,
Garcia Francisco J,
Carroll Kate S,
Morano Kevin A,
West James D
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.613.2
Subject(s) - electrophile , peroxiredoxin , chemistry , cysteine , biochemistry , chaperone (clinical) , thioredoxin , saccharomyces cerevisiae , peroxidase , yeast , enzyme , catalysis , medicine , pathology
Organisms have evolved a variety of defense mechanisms to deal with adverse environmental challenges, including exposure to reactive oxidants and organic electrophiles. In Saccharomyces cerevisiae , one of the proteins involved in defense against oxidants is the peroxiredoxin thioredoxin peroxidase 1 (Tsa1). Tsa1 possesses two highly reactive active site cysteine residues that undergo oxidation to form a disulfide bond during catalysis. Here, we report that Tsa1 is a cellular target of electrophilic alkylating agents. In cells treated with the electrophilic protein cross‐linkers diethyl acetylenedicarboxylate and divinyl sulfone, Tsa1 is cross‐linked to itself and other proteins, including cytosolic thioredoxins. Cross‐linking of Tsa1 is dependent on its active site cysteine residues, implying that these residues are subject to electrophilic modification. We tested whether pre‐treatment of Tsa1 with the alkylating agent N ‐ethylmaleimide inhibited its peroxidase activity and found that alkylation of the protein prevents its oxidation by H 2 O 2 . Despite this, yeast strains lacking tsa1 are hypersensitive to cell death induced by electrophiles and have an increased amount of proteins accumulating in insoluble aggregates under similar conditions. Since Tsa1 also functions as a molecular chaperone, our results suggest that its molecular chaperone activity may account for its protection against electrophiles.