Inducible gluconate permease in a gluconate kinase-deficient mutant of Escherichia coli.

Gluconate-resistant mutants were isolated from Escherichia coli strain DF 1070 deficient in phosphogluconate dehydrogenase (EC 1.1.1.44) and in phosphogluconate dehydrogenase (EC 4.2.1.12) which is inhibited by gluconate. Among the resistant mutants, AR 13 has been identified as a gluconate kinase (EC 2.7.1.12)-deficient strain. This mutant exhibits an inducible gluconate transport system capable of concentrating gluconate in the cytoplasm against a concentration gradient. The accumulated gluconate is subject to permanent turnover, and is not chemically modified. The kinetics of induction and deinduction indicate a single inducible component, rate limiting for the transport function, and the distribution of transport capacity among non-induced progeny of induced parents indicates that the inducible protein is membrane bound.