[Alpha-methylglucoside transmembrane phosphorylation and regulation of the beta-galactoside permease activity in E....

The interaction between alpha-methylglucoside (MeGlc) and beta-galactoside transport systems in E. coli K12 was studied. It was shown that an addition of MeGlc to bacterial cells leads to repression of [14C] lactose accumulation and o-nitrophenyl-beta-D-galactopyranoside (NO2PheGal) hydrolysis. The mutational damage of one of the components of the MeGlc transport system is accompanied by elimination of the glucoside inhibitory action. Intracellular MeGlcP and GlcP lower the efficiency of the transmembraneous transfer of beta-galactosides. The data obtained suggest that repression of the beta-galactoside permease activity during transport of the MeGlc is a result of two processes: i.e. phosphorylation-coupled translocation of MeGlc and intracellular accumulation of MeGlcP. An assumption on the intramembraneous interaction of enzyme IIGlc with beta-galactoside permease is made.