title: Regulation of carbohydrate permeases and adenylate cyclase in Escherichia coli. Studies with mutant strains in which enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system is thermolabile.
abstract: Carbohydrate uptake and cyclic adenosine 3':5'-monophosphate (cyclic AMP) synthesis were studied employing mutant strains of Escherichia coli in which Enzyme I of the phosphoenolpyruvate:sugar phosphotransferase system was heat-labile. Partial loss of Enzyme I activity, which resulted from incubation of cells at the nonpermissive temperature, depressed the rate and extent of methyl alpha-glucoside uptake. Temperature inactivation of Enzyme I also rendered cyclic AMP synthesis and the uptake of several carbohydrates (glycerol, maltose, melibiose, and lactose) hypersensitive to inhibition by methyl alpha-glucoside. Protein synthesis did not appear to be required for these effects. The parental strains and "revertant" strains in which Enzyme I was less sensitive to temperature did not exhibit heat-enhanced regulation. Inhibition was abolished by the crr mutation. The results suggest that Enzyme I functions as a catalytic component of the regulatory system. Simple positive selection procedures are described for the isolation of bacterial mutants which are deficient for either Enzyme I or the heat-stable protein of the phosphotransferase system.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism*; D001693:Biological Transport, Active; D050260:Carbohydrate Metabolism; D000242:Cyclic AMP / Q000096:biosynthesis; D004355:Drug Stability; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology*; D005838:Genotype; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008757:Methylglucosides / Q000494:pharmacology; D009154:Mutation; D010770:Phosphotransferases / Q000378:metabolism*; D013045:Species Specificity; D013696:Temperature
chemical_list: D026901:Membrane Transport Proteins; D008757:Methylglucosides; D000242:Cyclic AMP; D010770:Phosphotransferases; D000262:Adenylyl Cyclases