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

ArticleinBiochemical and Biophysical Research Communications 243(2):400-406 · February 1998with9 Reads
Impact Factor: 2.30 · DOI: 10.1006/bbrc.1998.8106


    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.