title: The yeast TUM1 affects production of hydrogen sulfide from cysteine treatment during fermentation.
abstract: The undesirable rotten-egg odour of hydrogen sulfide (H2S) produced by yeast shortly after yeast inoculation of grape musts might be an important source of desirable varietal thiols, which contribute to tropical aromas in varieties such as Sauvign-on Blanc. In this study, we observed that Saccharomyces cerevisiae strains produce an early burst of H2S from cysteine. Both Δmet2 and Δmet17 strains produce a larger burst, likely because they are unable to utilise the H2S in the sulfate assimilation pathway. For the first time, we show that TUM1 is partly responsible for the early production of H2S from cysteine. Overex-pressing TUM1 elevated production of H2S, whilst its deletion yields only half of the H2S. We further confirmed that yeast convert cysteine to H2S by analysing growth of mutants lacking components of the transsulfuration pathway. High concent-rations of cysteine overcame this growth block, but required TUM1 Collectively, the data indicate that S. cerevisiae does not convert cysteine to sulfate or sulfite, but rather to sulfide via a novel pathway that requires the action of Tum1p. The findi-ngs of this study may allow the improvement of commercial yeasts through the manipulation of sulfur metabolism that are better suited towards production of fruit-driven styles.
authors.affiliation: Department of Wine and Food Science, University of Adelaide, Adelaide 5064, Australia chien-wei.huang@adelaide.edu.au.
authors.forename: Chien-Wei
authors.initials: CW
authors.lastname: Huang
authors.affiliation: Department of Wine and Food Science, University of Adelaide, Adelaide 5064, Australia.
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Walker
authors.affiliation: Wine Science Programme, School of Chemical Sciences, University of Auckland, Auckland 1142, New Zealand.
authors.forename: Bruno
authors.initials: B
authors.lastname: Fedrizzi
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), Department of Microbial and Molecular Systems, KU Leuven, Leuven 3001, Belgium.
authors.forename: Miguel
authors.initials: M
authors.lastname: Roncoroni
authors.affiliation: Wine Science Programme, School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Gardner
authors.affiliation: Department of Wine and Food Science, University of Adelaide, Adelaide 5064, Australia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Jiranek
mesh_terms: D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000378:metabolism*; D005285:Fermentation; D006862:Hydrogen Sulfide / Q000378:metabolism*; D040641:Quantitative Trait Loci; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D002352:Carrier Proteins; D029701:Saccharomyces cerevisiae Proteins; C561713:Tum1 protein, S cerevisiae; D003545:Cysteine; D006862:Hydrogen Sulfide
keywords: Saccharomyces cerevisiae; TUM1; hydrogen sulfide; sulfate assimilation pathway; transsulfuration pathway; varietal thiols