X-Ray Structure of the Membrane-Bound Cytochrome C Quinol Dehydrogenase Nrfh Reveals Novel Haem Coordination.Rodrigues, M.L., Oliveira, T.F., Pereira, I.A.C., Archer, M.
(2006) EMBO J 25: 5951
- PubMed: 17139260
- DOI: https://doi.org/10.1038/sj.emboj.7601439
- Primary Citation of Related Structures:
- PubMed Abstract:
Oxidation of membrane-bound quinol molecules is a central step in the respiratory electron transport chains used by biological cells to generate ATP by oxidative phosphorylation. A novel family of cytochrome c quinol dehydrogenases that play an important role in bacterial respiratory chains was recognised in recent years. Here, we describe the first structure of a cytochrome from this family, NrfH from Desulfovibrio vulgaris, which forms a stable complex with its electron partner, the cytochrome c nitrite reductase NrfA. One NrfH molecule interacts with one NrfA dimer in an asymmetrical manner, forming a large membrane-bound complex with an overall alpha(4)beta(2) quaternary arrangement. The menaquinol-interacting NrfH haem is pentacoordinated, bound by a methionine from the CXXCHXM sequence, with an aspartate residue occupying the distal position. The NrfH haem that transfers electrons to NrfA has a lysine residue from the closest NrfA molecule as distal ligand. A likely menaquinol binding site, containing several conserved and essential residues, is identified.
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, ITQB-UNL, Oeiras, Portugal.