Evidence for cyclic GMP in the yeast Saccharomyces cerevisiae, and studies on its possible role in growth.

The yeast Saccharomyces cerevisiae is shown to be equipped with cyclic GMP, the level of which ranges from 6 pmol/10(9) cells with pressed baker's yeast to 21 pmol/10(9) cells with exponentially growing cells. In extracts from synchronized growing yeast, cyclic GMP increases stepwise, being doubled at the time of each mitosis. Theophylline and 3-isobutyl-1-methylxanthine induce a rapid increase of cyclic GMP, followed by a premature formation of the septal cell wall between mother cell and bud. The effects of 3-isobutyl-1-methylxanthine are reversible. Dibutyryl-cyclic GMP, and, after a pronounced lag, also dibutyryl-cyclic AMP, induce a premature cell division, too. Cholera toxin induces premature cell divisions without a preceding increase in cyclic GMP. Neither theophylline nor 3-isobutyl-1-methylxanthine, cholera toxin or one of the dibutyryl-cyclic nucleotides modify the growth rate of the culture. None of the agents has significant effects on the level of cyclic AMP. The results suggest that cyclic GMP possibly controls an early step of mitosis, whereas ADP-ribosylation might govern a subsequent event.