title: Genetic regulation of nitrate assimilation in Klebsiella pneumoniae M5al.
abstract: We isolated Mu dI1734 insertion mutants of Klebsiella pneumoniae that were unable to assimilate nitrate or nitrite as the sole nitrogen source during aerobic growth (Nas- phenotype). The mutants were not altered in respiratory (anaerobic) nitrate and nitrite reduction or in general nitrogen control. The mutations were linked and thus defined a single locus (nas) containing genes required for nitrate assimilation. beta-Galactosidase synthesis in nas+/phi(nas-lacZ) merodiploid strains was induced by nitrate or nitrite and was inhibited by exogenous ammonia or by anaerobiosis. beta-Galactosidase synthesis in phi(nas-lacZ) haploid (Nas-) strains was nearly constitutive during nitrogen-limited aerobic growth and uninducible during anaerobic growth. A general nitrogen control regulatory mutation (ntrB4) allowed nitrate induction of phi(nas-lacZ) expression during anaerobic growth. This and other results suggest that the apparent anaerobic inhibition of phi(nas-lacZ) expression was due to general nitrogen control, exerted in response to ammonia generated by anaerobic (respiratory) nitrate reduction.
authors.affiliation: Department of Microbiology, Cornell University, Ithaca, New York 14853-7201.
authors.forename: B M
authors.initials: BM
authors.lastname: Cali
authors.forename: J L
authors.initials: JL
authors.lastname: Micca
authors.forename: V
authors.initials: V
authors.lastname: Stewart
mesh_terms: D000693:Anaerobiosis; D002704:Chlorates / Q000494:pharmacology; D004252:DNA Mutational Analysis; D004251:DNA Transposable Elements; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D008040:Genetic Linkage; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics* / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism*; D009876:Operon; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D002704:Chlorates; D004251:DNA Transposable Elements; D009566:Nitrates; D009565:Nitrate Reductases; D050901:Nitrate Reductase; D001616:beta-Galactosidase