Trehalase activation induced by nutrients and metabolic inhibitors in Zygosaccharomyces rouxii

Abstract

Cells of Zygosaccharomyces rouxii suspended in buffer responded to the addition of both fermentable and nonfermentable sugars by increasing trehalase activity. This response was preceded by a cyclic-AMP (cAMP) signal. In contrast to previous findings in other yeast species, the glucose-induced trehalase activation is not repressed by glucose in these cells. The protonophore 2,4-dinitrophenol also triggered a transient activation of trehalase, but this response was not accompanied by an increase in cAMP. However, nitrogen sources, protein-synthesis inhibitors and the respiratory inhibitor sodium azide did not induce activation of trehalase. Incubation of cell extracts with ATP and cAMP produced an in vitro activation of trehalase suggesting that the enzyme may be stimulated in vivo by phosphorylation. The above results support the existence in Z. rouxii of both cAMP-dependent and cAMP-independent phosphorylation pathways which share trehalase as a molecular target. These activation pathways are markedly different in many respects from those induced in yeasts like Saccharomyces cerevisiae, Candida utilis , and Schizosaccharomyces pombe suggesting a species-specific design in the signal transduction systems involved in trehalase activation.