Article

Genomic DNA Cloning of the Region Encoding Nitric Oxide Reductase in Paracoccus halodenitrificansand a Structure Model Relevant to Cytochrome Oxidase

Institute for Molecular Science, Okazaki National Research Institutes, Okazaki, Japan.
Biochemical and Biophysical Research Communications (Impact Factor: 2.28). 02/1998; 243(2):400-406. DOI: 10.1006/bbrc.1998.8106

ABSTRACT The structural genes for the NO reductase inParacoccus halodenitrificans,norC,norB, andnorQwere sequenced. ThenorCandnorBencode the cytochromec(NorC) and cytochromeb(NorB) subunits, respectively. The matured NorC (17258 Da, 148 residues) has a binding motif (CXYCH) for hemec, which is axially coordinated by His65 and Met115. NorB (52337 Da, 451 residues) has twelve putative transmembrane helices and the 19% sequence homology with the subunit I of cytochrome oxidase fromParacoccus denitrificans.Several histidine and glutamate residues were identified as the ligands for two hemesband a non-heme iron in comparison with the sequence of cytochrome oxidase. The higher-order model structures constructed from the amino acid sequences of NorC and NorB showed the topology of the helical segments and the locations of the metal centers.

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