Physical and genetic characterization of the glnA--glnG region of the Escherichia coli chromosome.

Abstract

A fragment of the E. coli chromosome spanning glnA, the structural gene for glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] was cloned and characterized. The fragment also carries glnG, whose product is necessary for regulation of glnA expression, and a previously unidentified gene whose function was not discovered. Transcription of glnA and the newly identified gene occurs divergently from a region between the 2 genes. Transcription of glnA proceeds toward glnG, which is transcribed in the same direction. A region of DNA between glnA and glnG contains genetic information whose loss may result in the inability to reduce expression of glnA and other operons in response to ammonia (the GlnC phenotype).