Regulatory mutations in the Klebsiella aerogenes structural gene for glutamine synthetase.
Glutamine synthetase could be repressed several hundredfold rather than 6- to 10-fold as previously reported. Ammonia was not the primary repression signal for glutamine synthetase. Repression appeared to be mediated by a high level of glutamine and probably by a high ratio of glutamine to alpha-ketoglutarate. Mutations in glnA (the structural gene for glutamine synthetase) were seen to fall into three phenotypic groups: glutamine auxotrophs that produced no detectable glnA product; glutamine auxotrophs that produced a glnA product lacking enzymatic activity (and hence repressibility by ammonia) but were repressible under appropriate conditions; and glutamine synthetase regulatory mutants, whose glnA product was enzymatically active and not repressible under any conditions.
D000641:Ammonia / Q000378:metabolism; D004794:Enzyme Repression; D005796:Genes; D005974:Glutamate-Ammonia Ligase / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D005973:Glutamine / Q000378:metabolism; D006639:Histidine / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D009154:Mutation
D005973:Glutamine; D006639:Histidine; D000641:Ammonia; D005974:Glutamate-Ammonia Ligase