ANALYSIS OF LYSINE-DEPENDENT YEAST SPORULATION - A DECREASE IN CYCLIC-AMP IS NOT REQUIRED FOR INITIATION OF MEIOSIS AND SPORULATION IN SACCHAROMYCES-CEREVISIAE

Cells of the yeast Saccharomyces cerevisiae sporulated in nutrient-ric h 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 f requency reached about 60% after 5 d incubation. The L-lysine-dependen t sporulation system in nutrient-rich conditions was distinct from the currently used potassium-acetate-dependent system in nutrient-deficie nt conditions. Analysis of the L-lysine-dependent system indicated tha t, prior to entrance into meiosis and/or sporulation processes, the ye ast cells change in shape, their pool sizes for L-cysteine and glutath ione 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 meiosi s and/or sporulation.