ABSTRACT
As the first part of a study of pesticide toxicity we report the effects of the solvent dimethylsulfoxide (DMSO) on signal transduction in mutants of Saccharomyces cerevisiae. The enzymes of trehalose metabolism, which are activated and deactivated by a "glucose signal" and by heat shock treatment, were chosen as targets for this study. DMSO was shown to be able to permeate glucose and cAMP. The effects of glucose and cAMP were enhanced by pre-incubating the cells in the presence of DMSO. No effects were observed during the heat shock, suggesting that the solvent acts on the cell membrane. The results suggest that DMSO may be used as a vehicle for small molecules which do not easily penetrate yeast cell membranes, thus providing a new tool for biochemical and toxicological studies
Subject(s)
Dimethyl Sulfoxide/pharmacology , Glucose/metabolism , Mutation/genetics , Saccharomyces cerevisiae/genetics , Signal Transduction , Trehalose/metabolism , Cyclic AMP/metabolism , Enzyme Activation , Hot TemperatureABSTRACT
1. A regulatory mutant of Sccharomyces (fdp) unable to activate fructose 1,6-bisphosphatase present a normal response to the glucose and fructose signals as measured by trehalase activation, indicating that the inability of the strain to grow on these sugars is caused by a defect located beyond membrane interactions. 2. In vivo experiments with a mutant strain bearing a phosphoglucoisomerase gene (pgil-delta) deletion showed that activation of trehalase and deactivation of the tehalose-6-phosphate synthase complex occurred to the same extent whether glucose or fructose was used as signal. 3. These results suggest that fructose-2,6-bisphosphate is not involved in the interconversion of forms of the enzymes of trehalose metabolism. Furthermore, when fructose-2,6-bisphosphate was assayed on trehalose synthesizing activity using cell-free extracts and partially purified preparations of the complex, no effect was observed. 4. We conclude that regulation by cAMP fulfills the requirements for control of trehalose levels in Saccharomyces
Subject(s)
Cyclic AMP/metabolism , Disaccharides/metabolism , Fructosediphosphates/metabolism , Hexosediphosphates/metabolism , Saccharomyces cerevisiae/genetics , Trehalose/metabolism , Enzyme Activation , Glucose/metabolism , Protein Kinases/metabolism , Saccharomyces cerevisiae/growth & developmentABSTRACT
1. The effects of catbolite inactivation upon the trehalose pathway linked to maltose utilization were investigated in Saccharomyces cerevisiae. Mutant strains devoid of UDPG-trehalose synthase activity were used in this study. 2. Trehalose accumulation was also susceptible to catabolite inactivation as has been reported for the carrier protein, one of the components of the maltose system. Reversibility was only achieved when incubation with glucose did not exceed 5 min and was dependent upon protein sunthesis