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The IRC7 gene encodes cysteine desulphydrase activity and confers on yeast the ability to grow on cysteine as a nitrogen source
Author(s) -
Santiago Margarita,
Gardner Richard C.
Publication year - 2015
Publication title -
yeast
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.923
H-Index - 102
eISSN - 1097-0061
pISSN - 0749-503X
DOI - 10.1002/yea.3076
Subject(s) - cysteine , biochemistry , biology , cystathionine beta synthase , methionine , saccharomyces cerevisiae , yeast , cysteine metabolism , gene , microbiology and biotechnology , amino acid , enzyme
Although cysteine desulphydrase activity has been purified and characterized from Saccharomyces cerevisiae , the gene encoding this activity in vivo has never been defined. We show that the full‐length IRC7 gene, encoded by the YFR055W open reading frame, encodes a protein with cysteine desulphydrase activity. Irc7p purified to homogeneity is able to utilize l ‐cysteine as a substrate, producing pyruvate and hydrogen sulphide as products of the reaction. Purified Irc7p also utilized l ‐cystine and some other cysteine conjugates, but not l ‐cystathionine or l ‐methionine, as substrates. We further show that, in vivo , the IRC7 gene is both necessary and sufficient for yeast to grow on l ‐cysteine as a nitrogen source, and that overexpression of the gene results in increased H 2 S production. Strains overexpressing IRC7 are also hypersensitive to a toxic analogue, S ‐ethyl‐ l ‐cysteine. While IRC7 has been identified as playing a critical role in converting cysteine conjugates to volatile thiols that are important in wine aroma, its biological role in yeast cells is likely to involve regulation of cysteine and redox homeostasis. Copyright © 2015 John Wiley & Sons, Ltd.

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