CONTROL OF GLUTAMATE DEHYDROGENASE SYNTHESIS IN ESCHERICHIA COLI

The NADP-specific glutamate dehydrogenase (EC 1.4.1.4) activity of Escherichia coli B was assayed in cells grown on various nitrogen sources. Low activities were found after growth on nutrient broth, glutamate, aspartate, arginine or ornithine. Highest activities were found after growth on methionine or alanine as nitrogen source. Addition of alanine, glutamate, proline, lysine or threonine to media containing 5·10-2M ammonium reduced glutamate dehydrogenase activity. These results are interpreted in terms of a repression by glutamate. It is suggested that alanine is rapidly converted to pyruvate and that pyruvate and aspartate influence glutamate levels by a mass-action effect on the transaminase reactions. The derepression of glutamate dehydrogenase is relatively slow, and can be prevented by chloroamphenicol. © 1969.