The mechanism of glucose 6-phosphate transport by Escherichia coli.

摘要: To evaluate anion exchange as the mechanistic basis of sugar phosphate transport, natural and artificial membranes were used in studies glucose 6-phosphate (Glc-6-P) inorganic (Pi) accumulation by uhpT-encoded protein (UhpT) Escherichia coli. Experiments with intact cells demonstrated that UhpT catalyzed neutral internal external Pi, work everted well right-side-out membrane vesicles showed further mediated heterologous Pi Glc-6-P. When loaded but not when morpholinopropanesulfonate (MOPS), took up Glc-6-P to levels 100-fold above medium concentration a reaction unaffected ionophores valinomycin, valinomycin plus nigericin, carbonyl cyanide p-trifluoromethoxyphenylhydrazone. Similarly, capable only if suitable countersubstrate was available. Thus, MOPS-loaded vesicles, oxidative metabolism established proton-motive force supported proline or accumulation, transport found could accumulate during preincubation. After reconstitution into proteoliposomes it possible show level (17 560 nmol/mg protein) related directly Pi. These results are most easily understood E. coli occurs rather than nH+/anion support.