title: Nitrogen catabolic repression controls the release of volatile thiols by Saccharomyces cerevisiae during wine fermentation.
abstract: Volatile thiols such as 4-methyl-4-sulfanylpentan-2-one (4MSP) and 3-sulfanylhexan-1-ol (3SH) are aromatic molecules having an important organoleptic impact on white wines. These components are produced from inodorous nonvolatile cysteinylated precursors by Saccharomyces cerevisiae metabolic activity during alcoholic fermentation. Here we provide a new insight into the genetic determinism of the production of volatile thiols by yeast. Using a gene deletion approach, we investigated the role of three yeast beta-lyases and demonstrate that Irc7p, a putative cystathionine beta-lyase, is one of the main proteins catalyzing the 4MSP and 3SH release under enological conditions. Moreover, we demonstrate that Ure2p/Gln3p proteins mainly control the bioconversion of volatile thiols by the transcriptional regulation of the IRC7 gene through the general mechanism of nitrogen catabolic repression. Finally, our findings suggest that the enantiomer balance of 3SH may be modulated by activating specifically stereoselective enzymes such as Irc7p.
authors.affiliation: Faculté d'oenologie, UMR1219, INRA, Université Bordeaux2, Talence, France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Thibon
authors.forename: Philippe
authors.initials: P
authors.lastname: Marullo
authors.forename: Olivier
authors.initials: O
authors.lastname: Claisse
authors.forename: Christophe
authors.initials: C
authors.lastname: Cullin
authors.forename: Denis
authors.initials: D
authors.lastname: Dubourdieu
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Tominaga
mesh_terms: D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism; D005285:Fermentation; D005516:Food Microbiology; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D005979:Glutathione Peroxidase; D000441:Hexanols / Q000737:chemistry / Q000378:metabolism; D008190:Lyases / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism*; D009812:Odorants; D011328:Prions / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D014835:Volatilization; D014920:Wine / Q000382:microbiology*
chemical_list: D000441:Hexanols; D011328:Prions; D029701:Saccharomyces cerevisiae Proteins; D013438:Sulfhydryl Compounds; D014157:Transcription Factors; D005979:Glutathione Peroxidase; C067020:URE2 protein, S cerevisiae; D008190:Lyases; D013437:Carbon-Sulfur Lyases; C000607133:Irc7 protein, S cerevisiae; C019965:cystathionine beta-lyase; D009584:Nitrogen; C477019:3-mercaptohexanol