CYCLIC-AMP SIGNALING PATHWAY AND TREHALASE ACTIVATION IN THE FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

The response of derepressed cells of Schizosaccharomyces pombe to the addition of glucose included a marked and reversible activation of neu tral trehalase that was not produced in repressed cells. The protein s ynthesis inhibitor cycloheximide, the protonophore 2,4-dinitrophenol o r the uncoupler sodium azide also enhanced trehalase activity in derep ressed cells provided glucose was present in the incubation assays. Ho wever, only 2,4-dinitrophenol or cycloheximide was able to induce treh alase activation in repressed cells. Stimulation of trehalase by these compounds was preceded in all cases by a rapid increase in adenosine 3'-5'-cyclic monophosphate (cAMP) content. Since exogenous cAMP can ac tivate trehalase both in repressed and derepressed growing cells, the results provide evidence for the existence of an induced cAMP signalli ng pathway in the fission yeast with several entries for trehalase act ivation. The correlation between cAMP increase and trehalase activatio n was not maintained when the enzyme was heat-shock-activated, support ing the concept that trehalase activity can be also enhanced in cells by another mechanism in which cAMP does not act as second messenger.