Abstract
Cells of the yeast Saccharomyces cerevisiae sporulated in nutrient-rich medium containing L-lysine. Sporulation was specific to the presence of L-lysine and was initiated when the cellular content of this basic amino acid reached approximately 0.2-0.5 mmol (g cells)-1, at early stationary phase. The formation of asci was most efficient at pH 7.0 and 50-100 mM L-lysine; in these optimum conditions, the sporulation frequency reached about 60% after 5 d incubation. The L-lysine- dependent sporulation system in nutrient-rich conditions was distinct from the currently used potassium-acetate-dependent system in nutrient- deficient conditions. Analysis of the L-lysine-dependent system indicated that, prior to entrance into meiosis and/or sporulation processes, the yeast cells change in shape, their pool sizes for L- cysteine and glutathione alter, and they synthesize a protein with a molecular mass of 15 kDa. A low level of cAMP was not required for the entrance into meiosis and/or sporulation.