Posttranslational Regulatory Control of Trehalase Induced by Nutrients, Metabolic Inhibitors, and Physical Agents inPachysolen tannophilus

Abstract

Soto, T., Fernandez, J., Vicente-Soler, J., Cansado, J., and Gacto, M. 1996. Posttranslational regulatory control of trehalase induced by nutrients, metabolic inhibitors, and physical agents inPachysolen tannophilus. Fungal Genetics and Biology20,143–151. Trehalase activity in the yeastPachysolen tannophilusis due to a single enzyme with highest activity during exponential growth on glucose. Derepressed cells enhanced markedly the level of trehalase activity upon addition of glucose, 2,4-dinitrophenol, nitrogen sources, protein-synthesis inhibitors, or azide. The increase induced by the last three types of compounds required the presence of an energy source in the incubation assay. In glucose-repressed cells, only nitrogen sources and azide were able to produce trehalase activation. The increase in trehalase was preceded by a cAMP signal, suggesting that cAMP may be involved as second messenger in a signaling pathway for trehalase stimulation. When cells from either repressed or derepressed growing cultures were temperature shifted from 28 to 40°C, trehalase activity increased with negligible change in the cAMP level. This type of activation was not produced in cells from resting cultures. The increase in trehalase triggered by heating was independent on bothde novoprotein synthesis and the presence of glucose. Treatment by phosphatase of trehalase activated by either glucose or heat shock resulted in trehalase deactivation, indicating that phosphorylation of the enzyme protein occurs during activation. These data support that at least two independent mechanisms, involving different phosphorylation pathways, can promote trehalase activation inPa. tannophilus.Some functional features of these signaling pathways appear closer to those present in the fission yeastSchizosaccharomyces pombethan to those found in other budding yeasts likeSaccharomyces cerevisiaeorCandida utilis.