Genetics of the glutamine transport system in Escherichia coli

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Abstract
The active transport of glutamine by E. coli occurs via a single osmotic shock-sensitive transport system which is dependent on a periplasmic binding protein specific for glutamine. A mutant that had elevated levels of glutamine transport and overproduced the glutamine binding protein was isolated. From this strain many point mutants and deletion-carrying strains defective in glutamine transport were isolated by a variety of techniques. The genetic locus coding for the glutamine transport system, glnP, and the regulatory mutation which causes overproduction of the transport system were mapped at 17.7 min on the E. coli chromosome, and it was demonstrated that the glnP locus contains the structural gene for the glutamine binding protein. Evidence was also obtained that the glutamine transport system, by an unknown mechanism, plays a direct role in the catabolism of glutamate and, hence, of glutamine and proline as well.