Alanine catabolism in Klebsiella aerogenes: molecular characterization of the dadAB operon and its regulation by the nitrogen assimilation control protein.

ABSTRACT: Klebsiella aerogenes strains with reduced levels of D-amino acid dehydrogenase not only fail to use alanine as a growth substrate but also become sensitive to alanine in minimal media supplemented with glucose and ammonium. The inability of these mutant strains to catabolize the alanine provided in the medium interferes with both pathways of glutamate production. Alanine derepresses the nitrogen regulatory system (Ntr), which in turn represses glutamate dehydrogenase, one pathway of glutamate production. Alanine also inhibits the enzyme glutamine synthetase, the first enzyme in the other pathway of glutamate production. Therefore, in the presence of alanine, strains with mutations in dadA (the gene that codes for a subunit of the dehydrogenase) exhibit a glutamate auxotrophy when ammonium

SUBMITTER: Janes BK 

PROVIDER: S-EPMC106922 | biostudies-literature | 1998 Feb

REPOSITORIES: biostudies-literature