The NosX and NirX proteins of Paracoccus denitrificans are functional homologues: their role in maturation of nitrous oxide reductase.
The nos (nitrous oxide reductase) operon of Paracoccus denitrificans contains a nosX gene homologous to those found in the nos operons of other denitrifiers. NosX is also homologous to NirX, which is so far unique to P. denitrificans. Single mutations of these genes did not result in any apparent phenotype, but a double nosX nirX mutant was unable to reduce nitrous oxide. Promoter-lacZ assays and immunoblotting against nitrous oxide reductase showed that the defect was not due to failure of expression of nosZ, the structural gene for nitrous oxide reductase. Electron paramagnetic resonance spectroscopy showed that nitrous oxide reductase in cells of the double mutant lacked the Cu(A) center. A twin-arginine motif in both NosX and NirX suggests that the NosX proteins are exported to the periplasm via the TAT translocon.
Saunders
N F
NF
Department of Molecular Cell Physiology, Faculty of Biology, BioCentrum Amsterdam, Vrije Universiteit, Amsterdam, The Netherlands.
Hornberg
J J
JJ
Reijnders
W N
WN
Westerhoff
H V
HV
de Vries
S
S
van Spanning
R J
RJ
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins; D004578:Electron Spin Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009876:Operon; D010088:Oxidoreductases / Q000235:genetics*; D010231:Paracoccus denitrificans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D008565:Membrane Proteins; C401643:NirX protein, Paracoccus denitrificans; C108225:NosX protein, Rhizobium meliloti; D011994:Recombinant Proteins; D010088:Oxidoreductases; C022763:nitrous oxide reductase