Functional dissection of the proton pumping modules of mitochondrial complex I

Mitochondrial complex I, the largest and most complicated proton pump of the respiratory chain, links the electron transfer from NADH to ubiquinone to the pumping of four protons from the matrix into the intermembrane sp
Mitochondrial complex I, the largest and most complicated proton pump of the respiratory chain, links the electron transfer from NADH to ubiquinone to the pumping of four protons from the matrix into the intermembrane space. In humans, defects in complex I are involved in a wide range of degenerative disorders. Recent progress in the X-ray structural analysis of prokaryotic and eukaryotic complex I confirmed that the redox reactions are confined entirely to the hydrophilic peripheral arm of the L-shaped molecule and take place at a remarkable distance from the membrane domain. While this clearly implies that the proton pumping within the membrane arm of complex I is driven indirectly via long-range conformational coupling, the molecular mechanism and the number, identity, and localization of the pump-sites remains unclear. Here, we report that upon deletion of the gene for a small accessory subunit of the Yarrowia complex I, a stable subcomplex (nb8m delta) is formed that lacks the distal part of the membrane domain as revealed by single particle analysis. The analysis of the subunit composition of holo and subcomplex by three complementary proteomic approaches revealed that two (ND4 and ND5) of the three subunits with homology to bacterial Mrp-type Na+/H+ antiporters that have been discussed as prime candidates for harbouring the proton pumps were missing in nb8m delta. Nevertheless, nb8m delta still pumps protons at half the stoichiometry of the complete enzyme. Our results provide evidence that the membrane arm of complex I harbours two functionally distinct pump modules that are connected in series by the long helical transmission element recently identified by X-ray structural analysis.
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Metadaten
Author:Stefan Dröse, Stephanie Krack, Lucie Sokolova, Klaus Zwicker, Hans-Dieter Barth, Nina Morgner, Heinrich Heide, Mirco Steger, Esther Nübel, Volker Zickermann, Stefan Kerscher, Bernd Brutschy, Michael Radermacher, Ulrich Brandt
URN:urn:nbn:de:hebis:30-113551
DOI:http://dx.doi.org/10.1371/journal.pbio.1001128
ISSN:1545-7885
Parent Title (English):PLoS biology
Document Type:Article
Language:English
Date of Publication (online):2011/08/23
Date of first Publication:2011/08/23
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2011/08/26
Volume:9
Issue:(8): e1001128
Pagenumber:11
First Page:1
Last Page:11
Note:
Copyright: © 2011 Dröse et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
HeBIS PPN:274963051
Institutes:Biochemie und Chemie
Exzellenzcluster Makromolekulare Komplexe
Dewey Decimal Classification:570 Biowissenschaften; Biologie
Sammlungen:Universitätspublikationen
Sondersammelgebiets-Volltexte
Licence (German):License LogoCreative Commons - Namensnennung 3.0

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