A third subunit in ancestral cytochrome c-dependent nitric oxide reductases.

Authors :: Bricio C
Alvarez L
San Martin M
Schurig-Briccio LA
Gennis RB
Berenguer J
Source :: Applied and environmental microbiology [Appl Environ Microbiol] 2014 Aug; Vol. 80 (16), pp. 4871-8. Date of Electronic Publication: 2014 Jun 06.
Publication Year :: 2014
Abstract: Reduction of NO to N2O by denitrifiying bacteria is catalyzed either by a monomeric quinol-nitric oxide reductase (qNor) or by a heterodimeric cytochrome c-dependent nitric oxide reductase (cNor). In ancient thermophilic bacteria belonging to the Thermales and Aquificales phylogenetic groups, the cluster encoding the cNor includes a small third gene (norH), in addition to those encoding homologues to the subunits of a typical cNor (norC and norB). We show in Thermus thermophilus that the three genes are cotranscribed in a single mRNA from an inducible promoter. The isolation of individual nor mutants and the production in vivo of His-tagged NorH protein followed by immobilized-metal affinity chromatography (IMAC) allowed us to conclude that NorH constitutes a third subunit of the cNor from T. thermophilus, which is involved in denitrification in vivo, likely allowing more efficient electron transport to cNor.<br /> (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)