Properties of the Glutamate Transport System in Escherichia coli

摘要: The properties of the glutamate transport system in two glutamate-utilizing mutants Escherichia coli K-12 were investigated. Growth presence enhanced capacity bacteria for uptake. Accumulation was found to be an energy-linked highly temperature-dependent process. Nonlinear double reciprocal plots uptake obtained absence exogenous energy source and glucose or glycerol. Addition γ-aminobutyrate, succinate, ketoglutarate, aspartate accelerated brought about “normalization” its kinetics. Straight-line kinetics also observed when succinate served as energy. Under these conditions, α-ketoglutarate inhibited a noncompetitive fashion, whereas γ-aminobutyrate activated system. A number other amino acids act “noncompetitive” inhibitors. d-glutamate some derivatives with unsubstituted α-carboxylic α-amino group l-glutamate strictly competitive fashion. An allosteric permease model, consistent all findings, is proposed.