A genetic locus for the GltII-glutamate transport system in Escherichia coli

Growth of Escherichia coli on glutamate as sole carbon source only occurs in strains carrying mutations that increase the expression of genes encoding glutamate transport systems. From an analysis of mutants able to grow on glutamate we have identified a genetic locus that when mutated elevates the expression of the GltII glutamate/aspartate transport system. The mutants exhibit increased sensitivity to the toxic aspartate analogues cysteate and DL-threo-beta-hydroxyaspartate. Data from the analysis of mutants that are impaired in this transport activity are consistent with the presence of the structural gene for the transport system at the same genetic locus. The locus was mapped by P1 transduction to a region of the E. coli chromosome lying at approximately 92.5 min on the E. coli genetic map.