STUDIES ON THE CONTROL OF DEVELOPMENT - HIGHLY PHOSPHORYLATED NUCLEOTIDES (HPN) ARE CORRELATED WITH ASCOSPORE FORMATION IN SACCHAROMYCES-CEREVISIAE

Saccharomyces cerevisiae strain 1-2d can be induced to sporulate upon shift from rich growth medium to poor (potassium acetate) sporulation medium. Asci are observed after 24-30 h. Ascus formation is suppressed by the addition of nitrogen sources (yeast nitrogen base). When 32P-labelled phosphate is added to the sporulation medium and formic acid extracts of cells are chromatographed it is found that three highly phosphorylated nucleotides are produced almost immediately after shift down. These substances have been clearly identified as adenosine-5′,3′(2′)-bis-diphosphate (p2Ap2), adenosine-5′-triphosphate-3′(2′)-diphosphate (p3Ap2), and adenosine-5′,3′(2′)-bis-triphosphate (p3Ap3) by comparison with authentic samples obtained from sporulating B. subtilis cells. A close correlation of synthesis of these unusual nucleotides with ascospore formation in yeast could be shown. From this we conclude that sporulation in this organism may be initiated by the same molecular mechanism as was found to initiate sporulation in B. subtilis. The nucleotide p3Ap3 is synthesized in vitro by enzymes from cytoplasmic membranes and mitochondria apparently by a similar mechanism found for the synthesis of the same substance in B. subtilis. It is concluded, therefore, that upon nutrient starvation, the above mentioned highly phosphorylated nucleotides are synthesized by enzymes inhibited during vegetative growth but released from inhibition upon starvation. These substances then seem to cause changes in transcription leading to the formation of asci. © 1979 Springer-Verlag.