Gene structure and expression profile of cytochrome bc nitric oxide reductase from Hydrogenobacter thermophilus TK-6.
The genes for a nitric oxide reductase-like cytochrome bc complex were cloned from a thermophilic, chemolithoautotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6. The structural genes norC and norB, which encode cytochrome c and cytochrome b subunits of the complex respectively, are probably transcribed as a tricistronic operon with a following gene encoding a putative membrane protein. NorC has, unusually, two hydrophobic transmembrane spans in its N-terminus. Immunoblot analysis showed that expression of NorC was induced by nitrate, nitrite, or sodium nitropurusside, suggesting that the norCB gene product is a denitrification enzyme, nitric oxide reductase. The consensus sequences for the DNR/NnrR-type or the NorR/FhpR-type nitric oxide-sensing regulators of proteobacteria were not found in the norC promoter region, but consensus -35 and -10 sequences were found in this region. These results indicate that strain TK-6 has a nitrogen oxide-sensing regulatory system that differs from proteobacterial systems.
Suzuki
Miho
M
Department of Biotechnology, The University of Tokyo, Tokyo 113-8657, Japan.
Arai
Hiroyuki
H
Ishii
Masaharu
M
Igarashi
Yasuo
Y
D001419:Bacteria / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D045303:Cytochromes b / Q000235:genetics / Q000378:metabolism*; D045304:Cytochromes c / Q000235:genetics / Q000378:metabolism*; D005798:Genes, Bacterial; D009566:Nitrates / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009573:Nitrites / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011401:Promoter Regions, Genetic
D001426:Bacterial Proteins; D009566:Nitrates; D020030:Nitric Oxide Donors; D009573:Nitrites; D009599:Nitroprusside; D045304:Cytochromes c; D045303:Cytochromes b; D010088:Oxidoreductases; C034747:nitric-oxide reductase