Expression and characterization of the assimilatory NADH-nitrite reductase from the phototrophic bacterium Rhodobacter capsulatus E1F1.
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.
Olmo-Mira
M Francisca
MF
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Edificio Severo Ochoa, 1a planta, Campus de Rabanales, Córdoba 14071, Spain.
Cabello
Purificación
P
Pino
Carmen
C
Martínez-Luque
Manuel
M
Richardson
David J
DJ
Castillo
Francisco
F
Roldán
M Dolores
MD
Moreno-Vivián
Conrado
C
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
D009566:Nitrates; D011994:Recombinant Proteins; D009243:NAD; D005182:Flavin-Adenine Dinucleotide; D006418:Heme; C009272:siroheme; D009572:Nitrite Reductases; D010269:Paraquat