title: Bradyrhizobium japonicum NnrR, a denitrification regulator, expands the FixLJ-FixK2 regulatory cascade.
abstract: In Bradyrhizobium japonicum, a gene named nnrR was identified which encodes a protein with high similarity to FNR/CRP-type transcriptional regulators. Mutant strains carrying an nnrR null mutation were unable to grow anaerobically in the presence of nitrate or nitrite, and they lacked both nitrate and nitrite reductase activities. Anaerobic activation of an nnrR'-'lacZ fusion required FixLJ and FixK(2). In turn, N oxide-mediated induction of nir and nor genes encoding nitrite and nitric oxide reductase, respectively, depended on NnrR. Thus, NnrR expands the FixLJ-FixK(2) regulatory cascade by an additional control level which integrates the N oxide signal required for maximal induction of the denitrification genes.
authors.affiliation: Institute of Microbiology, Eidgenössische Technische Hochschule, CH-8092 Zürich, Switzerland. mesam@micro.biol.ethz.ch
authors.forename: Socorro
authors.initials: S
authors.lastname: Mesa
authors.forename: Eulogio J
authors.initials: EJ
authors.lastname: Bedmar
authors.forename: Astrid
authors.initials: A
authors.lastname: Chanfon
authors.forename: Hauke
authors.initials: H
authors.lastname: Hennecke
authors.forename: Hans-Martin
authors.initials: HM
authors.lastname: Fischer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D020369:Bradyrhizobium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006420:Hemeproteins / Q000235:genetics / Q000378:metabolism; D000071677:Histidine Kinase; D007506:Iron-Sulfur Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D010084:Oxidation-Reduction; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D006420:Hemeproteins; D007506:Iron-Sulfur Proteins; D009573:Nitrites; C066628:FixK protein, Bacteria; C069289:FixJ protein, Bacteria; D009569:Nitric Oxide; C067929:FixL protein, Bacteria; D000071677:Histidine Kinase