title: The wine yeast strain-dependent expression of genes implicated in sulfide production in response to nitrogen availability.
abstract: Sulfur metabolism in S. cerevisiae is well established, but the mechanisms underlying the formation of sulfide remain obscure. Here we investigated by real time RT-PCR the dependence of expression levels of MET3, MET5/ECM17, MET10, MET16 and MET17 along with SSU1 on nitrogen availability in two wine yeast strains that produce divergent sulfide profiles. MET3 was the most highly expressed of the genes studied in strain PYCC4072, and SSU1 in strain UCD522. Strains behaved differently according to the sampling times, with UCD522 and PYCC4072 showing the highest expression levels at 120h and 72h, respectively. In the presence of 267mg assimilable N/l, the genes were more highly expressed in strain UCD522 than in PYCC4072. MET5/ECM17 and MET17 were only weakly expressed in both strains under any condition tested. MET10 and SSU1 in both strains, but MET16 only in PYCC4072, were consistently up-regulated when sulfide production was inhibited. This study illustrates that strain genotype could be important in determining enzyme activities and therefore the rate of sulfide liberation. This linkage, for some yeast strains, of sulfide production to expression levels of genes associated to sulfate assimilation and sulfur amino acid biosynthesis could be relevant for defining new strategies for genetic improvement of wine yeasts.
authors.affiliation: Institute for Biotechnology and Bioengineering, Centre of Genomics and Biotechnology, (IBB/CGB-UTAD), University of Tras-os-Montes and Alto Douro, School of Life Sciences and Environment, Vila Real, Portugal. anamf@utad.pt
authors.forename: Ana
authors.initials: A
authors.lastname: Mendes-Ferreira
authors.forename: Catarina
authors.initials: C
authors.lastname: Barbosa
authors.forename: Elena
authors.initials: E
authors.lastname: Jimenez-Marti
authors.forename: Marcel Li
authors.initials: ML
authors.lastname: Del Olmo
authors.forename: Arlete
authors.initials: A
authors.lastname: Mendes-Faia
mesh_terms: D027321:Anion Transport Proteins / Q000378:metabolism; D005285:Fermentation; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006862:Hydrogen Sulfide / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013430:Sulfate Adenylyltransferase / Q000378:metabolism; D013440:Sulfides / Q000378:metabolism*; D014920:Wine / Q000382:microbiology*
chemical_list: D027321:Anion Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; C108311:Ssu1 protein, S cerevisiae; D013440:Sulfides; D013430:Sulfate Adenylyltransferase; D009584:Nitrogen; D006862:Hydrogen Sulfide