POSTTRANSLATIONAL REGULATORY CONTROL OF TREHALASE INDUCED BY NUTRIENTS, METABOLIC-INHIBITORS, AND PHYSICAL AGENTS IN PACHYSOLEN-TANNOPHILUS

Soto, T. Fernandez, J., Vicente-Soler, J., Cansado, J., and Gacto, M. 1996, Posttranslational regulatory control of trehalase induced by nut rients, metabolic inhibitors, and physical agents in Pachysolen tannop hilus, Fungal Genetics and Biology 20, 143-151. Trehalase activity in the yeast Pachysolen tannophilus is due to a single enzyme with highes t activity during exponential growth on glucose, Derepressed cells enh anced markedly the level of trehalase activity upon addition of glucos e, 2,4-dinitrophenol, nitrogen sources, protein-synthesis inhibitors, or azide, The increase induced by the last three types of compounds re quired the presence of an energy source in the incubation assay, In gl ucose-repressed cells, only nitrogen sources and azide were able to pr oduce trehalase activation, The increase in trehalase was preceded by a cAMP signal, suggesting that cAMP may be involved as second messenge r in a signaling pathway for trehalase stimulation, When cells from ei ther repressed or derepressed growing cultures were temperature shifte d from 28 to 40 degrees C, trehalase activity increased with negligibl e change in the cAMP level, This type of activation was not produced i n cells from resting cultures, The increase in trehalase triggered by heating was independent on both de novo protein synthesis and the pres ence of glucose, Treatment by phosphatase of trehalase activated by ei ther glucose or heat shock resulted in trehalase deactivation, indicat ing that phosphorylation of the enzyme protein occurs during activatio n, These data support that at least two independent mechanisms, involv ing different phosphorylation pathways, can promote trehalase activati on in Pa, tannophilus. Some functional features of these signaling pat hways appear closer to those present in the fission yeast Schizosaccha romyces pombe than to those found in other budding yeasts like Sacchar omyces cerevisiae or Candida utilis. (C) 1996 Academic Press, Inc.