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- Title
Structure of the V. cholerae Na<sup>+</sup>-pumping NADH:quinone oxidoreductase.
- Authors
Steuber, Julia; Vorburger, Thomas; Vohl, Georg; Casutt, Marco S.; Fritz, Günter; Diederichs, Kay
- Abstract
NADH oxidation in the respiratory chain is coupled to ion translocation across the membrane to build up an electrochemical gradient. The sodium-translocating NADH:quinone oxidoreductase (Na+-NQR), a membrane protein complex widespread among pathogenic bacteria, consists of six subunits, NqrA, B, C, D, E and F. To our knowledge, no structural information on the Na+-NQR complex has been available until now. Here we present the crystal structure of the Na+-NQR complex at 3.5 Å resolution. The arrangement of cofactors both at the cytoplasmic and the periplasmic side of the complex, together with a hitherto unknown iron centre in the midst of the membrane-embedded part, reveals an electron transfer pathway from the NADH-oxidizing cytoplasmic NqrF subunit across the membrane to the periplasmic NqrC, and back to the quinone reduction site on NqrA located in the cytoplasm. A sodium channel was localized in subunit NqrB, which represents the largest membrane subunit of the Na+-NQR and is structurally related to urea and ammonia transporters. On the basis of the structure we propose a mechanism of redox-driven Na+ translocation where the change in redox state of the flavin mononucleotide cofactor in NqrB triggers the transport of Na+ through the observed channel.
- Subjects
CRYSTAL structure; VIBRIO cholerae; NAD(P)H dehydrogenases; OXIDATION-reduction reaction; UBIQUINONES; COFACTORS (Biochemistry)
- Publication
Nature, 2014, Vol 516, Issue 7529, p62
- ISSN
0028-0836
- Publication type
Article
- DOI
10.1038/nature14003