Journal
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
Volume 108, Issue 19, Pages 7781-7786Publisher
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1010427108
Keywords
bioenergetics; EPR spectroscopy; metalloprotein; molybdenum
Categories
Funding
- Centre National de la Recherche Scientifique
- Agence Nationale de la Recherche
- Universite de Provence
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Anionic lipids play a variety of key roles in membrane function, including functional and structural effects on respiratory complexes. However, little is known about the molecular basis of these lipid-protein interactions. In this study, NarGHI, an anaerobic respiratory complex of Escherichia coli, has been used to investigate the relations in between membrane-bound proteins with phospholipids. Activity of the NarGHI complex is enhanced by anionic phospholipids both in vivo and in vitro. The anionic cardiolipin tightly associates with the NarGHI complex and is the most effective phospholipid to restore functionality of a nearly inactive detergent-solubilized enzyme complex. A specific cardiolipin-binding site is identified on the basis of the available X-ray diffraction data and of site-directed mutagenesis experiment. One acyl chain of cardiolipin is in close proximity to the heme b(D) center and is responsible for structural adjustments of b(D) and of the adjacent quinol substrate binding site. Finally, cardiolipin binding tunes the interaction with the quinol substrate. Together, our results provide a molecular basis for the activation of a bacterial respiratory complex by cardiolipin.
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