title: Evidence for the functional association of enzyme I and HPr of the phosphoenolpyruvate-sugar phosphotransferase system with the membrane in sealed vesicles of Escherichia coli.
abstract: Several independent assay procedures were used to estimate the activities of the enzyme constituents of the phosphoenolpyruvate-sugar phosphotransferase system (PTS) in osmotically shocked bacterial membrane vesicles. The soluble enzymes of the system were found to be in association with the membrane by several criteria. Phosphoenolpyruvate-dependent sugar phosphorylation was catalyzed by this membrane-bound enzyme system far more efficiently than by a mixture of the individual enzymes at corresponding concentrations. By contrast, the rates of the phosphoryl exchange reactions catalyzed by enzyme I and the enzyme II complexes were essentially the same for the associated and dissociated forms of the system. Functional association of the PTS-enzyme complex was stabilized by Mg++ and phosphoenolypyruvate and could be destroyed by detergent treatment, sonication, or by passage of the vesicle preparation through a French pressure cell. These results lead to the possibility that in the intact bacterial cell the soluble enzymes of the phosphotransferase system exist, in part, as peripheral membrane constituents associated with the integral membrane enzyme II complexes.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D008565:Membrane Proteins / Q000378:metabolism*; D017830:Octoxynol; D009994:Osmolar Concentration; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D017852:Phosphotransferases (Nitrogenous Group Acceptor); D011092:Polyethylene Glycols / Q000494:pharmacology; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D013010:Sonication; D014050:Toluene / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D003902:Detergents; D008565:Membrane Proteins; D012967:Sodium Dodecyl Sulfate; D014050:Toluene; D011092:Polyethylene Glycols; D017830:Octoxynol; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; D017852:Phosphotransferases (Nitrogenous Group Acceptor); C022360:phosphoenolpyruvate-protein phosphotransferase