A novel mechanism regulates H₂S and SO₂ production in Saccharomyces cerevisiae

Abstract

Sulfite (SO 2 ) plays an important role in flavour stability in alcoholic beverages, whereas hydrogen sulfide (H 2 S) has an undesirable aroma. To discover the cellular processes that control SO 2 and H 2 S production, we screened a library of Saccharomyces cerevisiae deletion mutants. Deletion of 12 genes led to increased H 2 S productivity. Ten of these genes are known to be involved in sulfur-containing amino acid metabolism, whereas UBI4 functions in the ubiquitin-proteasome system and SKP2 encodes an F-box-containing protein whose function is unknown. We found that the skp2 mutant accumulated H 2 S and SO 2 , because the adenosylphophosulfate kinase Met14p is a substrate of SCF Skp2 and more stable in the skp2 mutant than in the wild-type strain. Furthermore, the skp2 mutant grew more slowly than the wild-type strain under nutrient-limited conditions. Metabolome analysis showed that the concentration of intracellular cysteine is lower in the skp2 mutant than in the wild-type strain. The slow growth of the skp2 mutant was due to a lower concentration of intracellular cysteine, because the addition of cysteine suppressed the slow growth. In the skp2 mutant, the cysteine biosynthesis proteins Str2p, Str3p and Str4p are more stable than in the wild-type strain. Moreover, supplementation with methionine, S -adenosylmethionine, S -adenosylhomocysteine and homocysteine also suppressed the slow growth. Overexpression of STR1 or STR4 caused a more severe defect in the skp2 mutant. These results suggest that the balance of methionine and cysteine biosynthesis is important for yeast cell growth. Thus, Skp2p is one of the key components regulating this balance and H 2 S/SO 2 production.

Transcriptome-Based Characterization of Interactions between Saccharomyces cerevisiae and Lactobacillus delbrueckii subsp. bulgaricus in Lactose-Grown Chemostat Cocultures

“…Since downregulation of genes involved in cysteine, methionine, and threonine metabolism in the mixed cultures did not coincide with different concentrations of these amino acids relative to those of the pure cultures, it is unlikely to reflect a direct cross-feeding of these amino acids from the yeast to the bacterium. Alternatively, the downregulation of genes involved in synthesis of sulfur-containing amino acids might, for example, reflect a release of other reduced sulfur compounds (e.g., sulfide or sulfite [63]) by the yeast. The differential regulation of these genes in Lb.…”

Pleiotropic effects of Ubi4, a polyubiquitin precursor required for ubiquitin accumulation, conidiation and pathogenicity of a fungal insect pathogen

“…The function of Ubi4 has been well explored in various yeasts. Deletion of ubi4 in S. cerevisiae may result in increased sensitivity to oxidative stress, apoptotic phenotype and shortened lifespan (Zhao et al ., ) as well as induced H 2 S production (Yoshida et al ., ). Ubi4 is important for an integrity of spindle pole bodies at meiotic stage of fission yeast (Okazaki et al ., ) and essential for stress tolerance and improved fermentation during ethanol production of wine yeast (Wu et al ., ; Peter et al ., ).…”

Identification of new Saccharomyces cerevisiae variants of the MET2 and SKP2 genes controlling the sulfur assimilation pathway and the production of undesirable sulfur compounds during alcoholic fermentation

“…Furthermore, Natarjan et al [ 16 ] showed that several genes of sulfur metabolism are also controlled by GCN4 , which regulates the transcriptional activity of genes involved in amino acid synthesis either directly ( MET16 and MET25 ) or indirectly ( SUL1 , SUL2 , MET3 , MET14 , MET10 , MET1 , MET25 , MET6 , MET2 , MET28 and MET4 ). In addition, Yoshida et al [ 17 ] identified a new mechanism involving the F-box protein skp2p, which forms part of a complex, SCF SKP2 , which controls the stability of Met14p, and regulates the transcription of the STR1 , 2 and 4 genes.…”