Gene Structure and Expression Profile of Cytochrome bc Nitric Oxide Reductase from Hydrogenobacter thermophilus TK-6
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The genes for a nitric oxide reductase-like cytochrome <I>bc</I> complex were cloned from a thermophilic, chemolithoautotrophic hydrogen-oxidizing bacterium, <I>Hydrogenobacter thermophilus</I> TK-6. The structural genes <I>norC</I> and <I>norB</I>, which encode cytochrome <I>c</I> and cytochrome <I>b</I> 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 <I>norCB</I> 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 <I>norC</I> 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.
- Agricultural and Biological Chemistry
Agricultural and Biological Chemistry 70(7), 1666-1671, 2006-07-23
Japan Society for Bioscience, Biotechnology, and Agrochemistry