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  • Title: Regulatory mutations in the Klebsiella aerogenes structural gene for glutamine synthetase.
    Author: Bender RA, Magasanik B.
    Journal: J Bacteriol; 1977 Oct; 132(1):100-5. PubMed ID: 21157.
    Abstract:
    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.
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