title: A third subunit in ancestral cytochrome c-dependent nitric oxide reductases.
abstract: Reduction of NO to N2O by denitrifiying bacteria is catalyzed either by a monomeric quinol-nitric oxide reductase (qNor) or by a heterodimeric cytochrome c-dependent nitric oxide reductase (cNor). In ancient thermophilic bacteria belonging to the Thermales and Aquificales phylogenetic groups, the cluster encoding the cNor includes a small third gene (norH), in addition to those encoding homologues to the subunits of a typical cNor (norC and norB). We show in Thermus thermophilus that the three genes are cotranscribed in a single mRNA from an inducible promoter. The isolation of individual nor mutants and the production in vivo of His-tagged NorH protein followed by immobilized-metal affinity chromatography (IMAC) allowed us to conclude that NorH constitutes a third subunit of the cNor from T. thermophilus, which is involved in denitrification in vivo, likely allowing more efficient electron transport to cNor.
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: C
authors.initials: C
authors.lastname: Bricio
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Alvarez
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: M
authors.initials: M
authors.lastname: San Martin
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, Illinois, USA.
authors.forename: L A
authors.initials: LA
authors.lastname: Schurig-Briccio
authors.affiliation: Department of Biochemistry, University of Illinois, Urbana, Illinois, USA.
authors.forename: R B
authors.initials: RB
authors.lastname: Gennis
authors.affiliation: Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid-Consejo Superior de Investigaciones Científicas, Madrid, Spain jose.berenguer@uam.es.
authors.forename: J
authors.initials: J
authors.lastname: Berenguer
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D009876:Operon; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D016963:Thermus thermophilus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; D009569:Nitric Oxide; D045304:Cytochromes c; D010088:Oxidoreductases; C034747:nitric-oxide reductase