A sulphite-inducible form of the sulphite efflux gene SSU1 in a Saccharomyces cerevisiae wine yeast

Abstract

Sulphite is widely used as a preservative in foods and beverages for its antimicrobial and antioxidant activities, particularly in winemaking where SO 2 is frequently added. Thus, sulphite resistance mechanisms have been extensively studied in the fermenting yeast Saccharomyces cerevisiae. Sulphite detoxification, involving a plasma membrane protein encoded by the SSU1 gene, is the most efficient resistance mechanism in S. cerevisiae. In this study, we characterized the unusual expression pattern of SSU1 in the wine strain 71B. We provide, for the first time, evidence of SSU1 induction by sulphite. The study of SSU1 expression during fermentation and in different growth conditions showed that sulphite is the main regulator of SSU1 expression, explaining its specific pattern. Combining analyses of gene expression and growth behaviour in response to sulphite, we found that 71B displayed unique behavioural patterns in response to sulphite pre-adaptation that may be explained by changes in SSU1 expression. Examination of the genomic organization of the SSU1 locus and sequencing of the region revealed three different alleles in 71B, two of which corresponded to translocated VIII-XVI forms. The lack of differences between promoter regions suggests that this inducible SSU1 expression pattern is due to modification of regulatory/signalling pathways.

Genome-Wide Transcriptional Profiling of the Purple Sulfur Bacterium Allochromatium vinosum DSM 180T during Growth on Different Reduced Sulfur Compounds

“…The kanamycin ⍀ cassette replacing Alvin_3072 therefore most likely also prevents formation of the Alvin_3073-encoded transporter, and more experiments are needed to exactly dissect the effect exerted by the interposon. The protein Alvin_3073 belongs to a family of transporters that includes a malate uptake system in the yeast Schizosaccharomyces pombe (63), a tellurite resistance protein in Escherichia coli (64), and notably, a sulfite efflux pump in Saccharomyces cerevisiae and other fungi, including Aspergillus fumigatus (65). Alvin_3072 is conserved in several sulfide-oxidizing bacteria (see Fig.…”

Sulfite oxidation in the purple sulfur bacterium Allochromatium vinosum: identification of SoeABC as a major player and relevance of SoxYZ in the process

“…Other described sulfite efflux pumps stem from fungal sources, e.g. SSU1 from Saccharomyces cerevisiae (Park & Bakalinsky, 2000;Nardi et al, 2010) or Aspergillus fumigatus (Léchenne et al, 2007). However, genes encoding closely related proteins are not present in the currently sequenced purple sulfur bacteria with the exception of Thiorhodococcus drewsii.…”

Surviving in the presence of sulphur dioxide: strategies developed by wine yeasts

“…On the contrary, Kloeckera apiculata and Hansenula anomala were shown to be highly sensitive to SO 2 (Warth 1985). Strains of S. cerevisiae have been shown to be fairly tolerant to SO 2 in general when compared with other yeast species but display highly diverse SO 2 tolerance (Divol et al 2006;Nardi et al 2010). It was reported that in a spontaneous wine fermentation, 50 mg/L SO 2 in general is sufficient to inhibit most of the non-Saccharomyces yeasts found in grape juice except Candida spp.…”

“…However, there is an absence of heterozygosity for the untranslocated locus (i.e. on chromosome VIII) (Aa et al 2006;Liti et al 2009;Nardi et al 2010). As wine strains of S. cerevisiae exhibit different degrees of ploidy and different levels of heterozygosity, the number of SSU1 and SSU1-R could potentially explain the diverse range of resistance observed between strains.…”

“…A strong heterozygosity has been observed for the translocated SSU1 locus (i.e. on chromosome XVI) (Nardi et al 2010) with numerous strain-dependent nucleotide polymorphisms (Aa et al 2006). However, there is an absence of heterozygosity for the untranslocated locus (i.e.…”