title: Characterization of mutations that lie in the promoter-regulatory region for glnA, the structural gene encoding glutamine synthetase.
abstract: In enteric bacteria products of nitrogen regulatory genes ntrA, ntrB and ntrC are known to regulate transcription both positively and negatively at glnA, the structural gene encoding glutamine synthetase [L-glutamate:ammonia-ligase (ADP-forming), EC 6.3.1.2]. We have characterized two types of cis-acting mutations in the glnA promoter-regulatory region. One type, which we have called promoter Up [glnAp (Up)], elevates transcription of glnA to high levels without need for ntr-mediated activation but leaves expression sensitive to ntr-mediated repression. The other type renders glnA transcription insensitive to repression but leaves it normally responsive to activation. Properties of the two types of promoter-regulatory mutations suggest that sites for ntr-mediated activation of glnA transcription are functionally distinct from sites for ntr-mediated repression.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D005809:Genes, Regulator; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D009876:Operon; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics; D012486:Salmonella typhimurium / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D012097:Repressor Proteins; D005974:Glutamate-Ammonia Ligase