title: Expression and characterization of the assimilatory NADH-nitrite reductase from the phototrophic bacterium Rhodobacter capsulatus E1F1.
abstract: A nas gene region from Rhodobacter capsulatus E1F1 containing the putative nasB gene for nitrite reductase was previously cloned. The recombinant His(6)-NasB protein overproduced in E. coli showed nitrite reductase activity in vitro with both reduced methyl viologen and NADH as electron donors. The apparent K ( m ) values for nitrite and NADH were 0.5 mM and 20 microM, respectively, at the pH and temperature optima (pH 9 and 30 degrees C). The optical spectrum showed features that indicate the presence of FAD, iron-sulfur cluster and siroheme as prosthetic groups, and nitrite reductase activity was inhibited by sulfide and iron reagents. These results indicate that the phototrophic bacterium R. capsulatus E1F1 possesses an assimilatory NADH-nitrite reductase similar to that described in non-phototrophic organisms.
authors.affiliation: Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Edificio Severo Ochoa, 1a planta, Campus de Rabanales, Córdoba 14071, Spain.
authors.forename: M Francisca
authors.initials: MF
authors.lastname: Olmo-Mira
authors.forename: Purificación
authors.initials: P
authors.lastname: Cabello
authors.forename: Carmen
authors.initials: C
authors.lastname: Pino
authors.forename: Manuel
authors.initials: M
authors.lastname: Martínez-Luque
authors.forename: David J
authors.initials: DJ
authors.lastname: Richardson
authors.forename: Francisco
authors.initials: F
authors.lastname: Castillo
authors.forename: M Dolores
authors.initials: MD
authors.lastname: Roldán
authors.forename: Conrado
authors.initials: C
authors.lastname: Moreno-Vivián
mesh_terms: D003001:Cloning, Molecular; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry; D006418:Heme / Q000031:analogs & derivatives / Q000737:chemistry; D009243:NAD / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism; D009572:Nitrite Reductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010269:Paraquat / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D016354:Rhodobacter capsulatus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development
chemical_list: D009566:Nitrates; D011994:Recombinant Proteins; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D006418:Heme; C009272:siroheme; D009572:Nitrite Reductases; D010269:Paraquat