Defective enzyme II-BGlc of the phosphoenolpyruvate:sugar phosphotransferase system leading to uncoupling of transport and phosphorylation in Salmonella typhimurium

Abstract

Transport and phosphorylation of glucose via enzymes II-A/II-B and 1j-Bj'; of the phosphoenolpyruvate:sugar phosphotransferase system are tightly coupled in Salmonella typhimurium. Mutant strains (pts) that lack the phosphorylating proteins of this system, enzyme I and HPr, are unable to transport or to grow on glucose. From ptsHl deletion strains of S. typhimurium, nmutants were isolated that regained growth on and transport of glucose. Several lines of evidence suggest that these Glcmutants have an altered enzyme II-B'";, as follows. (i) Insertion of a ptsG: :TnlO mutation (resulting in a defective II-B('r) abolished growth on and transport of glucose in these Glc+ strains. Introduction of a ptsM mutation, on the other hand, which abolishes II-A/II-B activity, had no effect. (ii) Methyl a-glucoside transport and phosphorylation (specific for Il-B("') was lowered or absent in ptsH+,I+ transductants of these Glc' strains. Transport and phosphorylation of other phosphoenolpyrurate:sugar phosphotransferase system sugars were normal. (iii) Membranes isolated from these Glc' mutants were unable to catalyze transphosphorylation of methyl a-glucoside by glucose 6-phosphate, but transphosphorylation of mannose by glucose 6-phosphate was normal. (iv) The mutation was in the ptsG gene or closely linked to it. We conclude that the altered enzyme II-B(;1' has acquired the capacity to transport glucose in the absence of

Changes in the proteome of Salmonella enterica serovar Thompson as stress adaptation to sublethal concentrations of thymol

“…The EIIA domain is first phosphorylated by phospho‐Hpr and then it transfers the phosphoryl group to the EIIB domain. In the absence of the general phosphoryl‐transfering proteins, the enzyme II do not catalyze the transport and strains that lack Hpr and enzyme I cannot grow on glucose 21. Postma 21 reported of a mutant of S. typhimurium in which transport and phosphorylation of glucose via enzyme IIB are uncoupled.…”

“…In the absence of the general phosphoryl‐transfering proteins, the enzyme II do not catalyze the transport and strains that lack Hpr and enzyme I cannot grow on glucose 21. Postma 21 reported of a mutant of S. typhimurium in which transport and phosphorylation of glucose via enzyme IIB are uncoupled. The mutated enzyme IIB catalyzes the influx of glucose in the cells in the absence of concomitant phosphorylation, acting like a pore always open under all conditions.…”

Involvement of lactose enzyme II of the phosphotransferase system in rapid expulsion of free galactosides from Streptococcus pyogenes

“…Considerable evidence suggests that the enzymes II are essentially inQapable of catalyzing facilitated uptake of sugars without concomitant phosphorylation (21,28,31). Uptake of free sugars by the enzymes II has been demonstrated only under certain abnormal physiological conditions (33) and in mutants with genetically altered enzymes II (20). Enzyme (33).…”

Glucose transport in Escherichia coli

“…Two observations support this mechanistic model, Wild-type U Gle can phosphorylate intracellular glucose without concomitant transport (see 2.2.3. ), and mutant forms of n Ole ('uncoupled' II GIe , [31]) facilitate glucose transport along a concentration gradient although they are unable to phosphorylate glucose. It is not yet known which parts of the U Gle molecule constitute the transport pathway for glucose.…”