The IRC7 gene encodes cysteine desulphydrase activity and confers on yeast the ability to grow on cysteine as a nitrogen source. Issue 7 (6th May 2015)

• Record Type: Journal Article
• Authors: Santiago, Margarita; Gardner, Richard C.
• Is Part Of: Yeast. Volume 32:Issue 7(2015:Jul.)
• Page Start: 519
• Page End: 532
• Publication Date: 2015-05-06
• Subjects: Yeast -- Periodicals; Yeasts -- Periodicals; Yeasts -- genetics -- Periodicals; Electronic journals; 547
• DOI: 10.1002/yea.3076
• Languages: English
• ISSNs: 0749-503X

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Although cysteine desulphydrase activity has been purified and characterized from <italic>Saccharomyces cerevisiae</italic>, the gene encoding this activity <italic>in vivo</italic> has never been defined. We show that the full‐length <italic>IRC7</italic> gene, encoded by the YFR055W open reading frame, encodes a protein with cysteine desulphydrase activity. Irc7p purified to homogeneity is able to utilize <sc>l</sc>‐cysteine as a substrate, producing pyruvate and hydrogen sulphide as products of the reaction. Purified Irc7p also utilized <sc>l</sc>‐cystine and some other cysteine conjugates, but not <sc>l</sc>‐cystathionine or <sc>l</sc>‐methionine, as substrates. We further show that, <italic>in vivo</italic>, the <italic>IRC7</italic> gene is both necessary and sufficient for yeast to grow on <sc>l</sc>‐cysteine as a nitrogen source, and that overexpression of the gene results in increased H₂S production. Strains overexpressing <italic>IRC7</italic> are also hypersensitive to a toxic analogue, <italic>S</italic>‐ethyl‐<sc>l</sc>‐cysteine. While <italic>IRC7</italic> 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 &amp; Sons, Ltd.</p> </abstract>