Abstract
The nature of the interaction of glucose with toluene-treated cells of Escherichia coli leading to inhibition of adenylate cyclase was examined by the use of analogues. Those analogues with variations of the substituents about carbon atoms 1 or 2 (e.g. alpha-methylglucoside or 2-deoxyglucose) are inhibitory, and they are also substrates of the phosphoenolpyruvate-dependent sugar phosphotransferase system. Analogues with changes in other parts of the molecule (e.g. 3-O-methylglucose or galactose), L-glucose and several disaccharides and pentoses, do not inhibit adenylate cyclase and are not substrates of the phosphotransferase system. This correlation suggests some functional relationship between the adenylate cyclase and phosphotransferase systems. Further studies were done with mutants defective in glucose enzymes II of the phosphotransferase system (designated GPT and MPT); these two activities are measured by phosphorylation of alpha-methyl-glucoside and 2-deoxyglucose, respectively. The wild-type parent phosphorylates both analogues, and both inhibit adenylate cyclase. In the GPT- mutant, alpha-methylglucoside does not inhibit adenylate cyclase and is not phosphorylated, while 2-deoxyglucose is inhibitory and phosphorylated. In the GPT- MPT- double mutant, adenylate cyclase activity is present, but neither alpha-methylglucoside nor 2-deoxyglucose inhibits adenylate cyclase, and neither sugar is phosphorylated. These studies demonstrate that glucose inhibition of adenylate cyclase in toluene-treated cells requires an interaction of this sugar with either the GPT or mpt enzyme II of the phosphotransferase system.
Highlights
Involvement of the Glucose Enzymes II of the Sugar Phosphotransferase System in the Regulation of Adenylate
The coincident development of inhibitory activity by sugars other than glucose with the development of transport systems for these sugars suggested some relationship between transport and the regulation of adenylate cyclase. We have extended these studies by determining the structure activity requirements of the glucose molecule necessary for inhibition of adenylate cyclase activity for glucose-grown cells
In contrast to glucose and mannose which were active, GDP-glucose and GDP-mannose were inactive. 5-Thioglucose, first reported by Feather and Whistler, is the nearest structural analogue of glucose and has the ring oxygen substituted by sulfur
Summary
Involvement of the Glucose Enzymes II of the Sugar Phosphotransferase System in the Regulation of Adenylate. The nature of the interaction of glucose with toluene-treated cells of Escherichia coli leading to inhibition of adenylate cyclase was examined by the use of analogues. Those analogues with variations of the substituents about carbon atoms 1 or 2 (e.g. cu-methylglucoside or 2-deoxyglucose) are inhibitory, and they are substrates of the phosphoenolpyruvate-dependent sugar phosphotransferase system. Analogues with changes in other parts of the molecule (e.g. 3-0-methylglucose or galactose), L-glucose and several disaccharides and pentoses, do not inhibit adenylate cyclase and are not substrates of the phosphotransferase system.
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