SENSITIVITY OF FRUCTOSE-1,6-BISPHOSPHATASE TO GLUCOSE AND CYCLIC-AMP IN THE FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

Stationary phase cells from resting cultures of Schizosaccharomyces po mbe, suspended in buffer, did not decrease fructose-1,6-bisphosphatase (FbPase) activity upon addition of glucose to the call suspension. In contrast, the addition of glucose to cells from derepressed growing c ultures resulted in a 4- to 5-fold reduction in FbPase activity within minutes after the addition of the sugar. This response was independen t of protein synthesis, was accompanied by a rise in the cyclic AMP (c AMP) level and was concomitant with an increase in the activity of neu tral trehalase. The addition of exogenous cAMP to these cells provoked a decrease in FbPase similar to that induced by glucose. The occurren ce of a glucose-induced cAMP signal was not sufficient to trigger the decrease in FbPase activity, which appeared to require additional tran sduction elements not active in growth-arrested cells. In assays perfo rmed in vitro it was found that the enzyme activity was strongly inhib ited by fructose-2,6-bisphosphate.