Sulfur and adenine metabolisms are linked, and both modulate sulfite resistance in wine yeast.

Sulfite treatment is the most common way to prevent grape must spoilage in winemaking because the yeast Saccharomyces cerevisiae is particularly resistant to this chemical. In this paper we report that sulfite resistance depends on sulfur and adenine metabolism. The amount of adenine and methionine in a chemically defined growth medium modulates sulfite resistance of wine yeasts. Mutations in the adenine biosynthetic pathway or the presence of adenine in a synthetic minimal culture medium increase sulfite resistance. The presence of methionine has the opposite effect, inducing a higher sensitivity to SO(2). The concentration of methionine, adenine, and sulfite in a synthetic grape must influences the progress of fermentation and at the transcriptional level the expression of genes involved in sulfur (MET16), adenine (ADE4), and acetaldehyde (ALD6) metabolism. Sulfite alters the pattern of expression of all these genes. This fact indicates that the response to this stress is complex and involves several metabolic pathways.