title: The cydR gene product, required for regulation of cytochrome bd expression in the obligate aerobe Azotobacter vinelandii, is an Fnr-like protein.
abstract: The cytochrome bd complex in the obligately aerobic diazotroph Azotobacter vinelandii is an oxidase, which, in vivo, has a low affinity for oxygen and is required for respiratory protection of nitrogenase. Mutations caused by insertion of Tn5-B20 upstream of the structural genes (cydAB) for cytochrome bd result in over-expression of this oxidase and, for unexplained reasons, inability of the organism to grow microaerobically. Cloning and sequencing of this upstream region revealed a gene, cydR. The deduced amino acid sequence of CydR indicates that it is a new member of the Fnr Class of regulators and that it represses cydAB expression. Refined mapping data for three insertions in cydR are presented. The cloned cydR gene complemented anaerobic growth of Escherichia coli fnr mutants and strongly enhanced expression of a narG-lacZ fusion in an E. coli fnr mutant.
authors.affiliation: The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Guanghui
authors.initials: G
authors.lastname: Wu
authors.affiliation: Nitrogen Fixation Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, UK.
authors.forename: Susan
authors.initials: S
authors.lastname: Hill
authors.affiliation: The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Mark J S
authors.initials: MJS
authors.lastname: Kelly
authors.affiliation: Nitrogen Fixation Laboratory, John Innes Centre, Colney, Norwich NR4 7UH, UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Sawers
authors.affiliation: The Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, The University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Poole
mesh_terms: D000595:Amino Acid Sequence; D000693:Anaerobiosis; D016948:Azotobacter vinelandii / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D003573:Cytochrome b Group; D003580:Cytochromes / Q000235:genetics* / Q000378:metabolism; D045222:Electron Transport Chain Complex Proteins; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D007506:Iron-Sulfur Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; C107798:CydR protein, Azotobacter vinelandii; D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; C060704:FNR protein, E coli; D007506:Iron-Sulfur Proteins; D012097:Repressor Proteins; D010088:Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli