[2 phosphotransferase systems that control the second stage of phosphoenolpyruvate-dependent glucose phosphorylation...

Analysis of E. coli W mutants defective in glucose transport suggests an existence of two enzyme systems which carry out the second step of phosphoenolpyruvate (PEP)-dependent glucose phosphorylation, thus controlling the glucose transport into E. coli cells. One system (PTS-glu-alpha) controls phosphorylation and transport of both glucose and alpha-methylglucoside, the other system (PTS-glu-beta) controls phosphorylation and transport of glucose only. PTS-glu-alpha system is damaged in the mutants studied, but PTS-glu-beta system is intact. On account of this fact the mutants do not uptake 14-C-alpha-methylglucoside and their extracts are practically incapable of its phosphorylation, phosphoenolpyruvate being used as phosphate donor. At the same time the mutants are capable of 14-C-glucose uptake and PEP-dependent 14-C-glucose phosphorylation. In one of the strain, having the intact PTS-glu-alpha system, the uptake of glucose and alpha-methylglucoside was stimulated by the addiction of glucose in the cultural medium. No such effect was observed in bacteria with the disturbed PTS-glu-alpha system and the intact PTS-glu-beta system. Probably, the PTS-glu-alpha system can be inducible, in contrast with the PTS-glu-beta system. The damage of the PTS-glu-alpha system results in resistance of bacteria to glucose-induced inhibition of the enzyme synthesis.