Function of the Rhizobium etli CFN42 nirK gene in nitrite metabolism.
Rhizobium etli CFN42 is not capable of growing anaerobically with nitrate but it grows with nitrite as a terminal electron acceptor. This bacterium contains the nirK gene encoding the copper-containing Nir (nitrite reductase), which is located on the cryptic plasmid pCFN42f. Mutational analysis has demonstrated that a nirK deficient mutant was not capable of growing under nitrite-respiring conditions. Moreover, microaerobic growth of this mutant was inhibited by the presence of nitrite. Nir activity and nitrite uptake were highly diminished in a nirK mutant, compared with the wild-type levels after incubation under anaerobic conditions. Our results suggest that the copper-containing Nir may have both a respiratory and a nitrite-detoxifying role in R. etli.
Bueno
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E
Departamento de Microbiología del Suelo y Sistemas Simbióticos, Estación Experimental del Zaidín, CSIC, P.O. Box 419, 18080 Granada, Spain.
Gómez-Hernández
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N
Girard
L
L
Bedmar
E J
EJ
Delgado
M J
MJ
D005798:Genes, Bacterial; D050901:Nitrate Reductase; D009565:Nitrate Reductases / Q000235:genetics / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism*; D042163:Rhizobium etli / Q000235:genetics*
D009573:Nitrites; D009565:Nitrate Reductases; D050901:Nitrate Reductase