PMID:21822288
| Citation |
Efremov, RG and Sazanov, LA (2011) Structure of the membrane domain of respiratory complex I. Nature 476:414-20 |
|---|---|
| Abstract |
Complex I is the first and largest enzyme of the respiratory chain, coupling electron transfer between NADH and ubiquinone to the translocation of four protons across the membrane. It has a central role in cellular energy production and has been implicated in many human neurodegenerative diseases. The L-shaped enzyme consists of hydrophilic and membrane domains. Previously, we determined the structure of the hydrophilic domain. Here we report the crystal structure of the Esherichia coli complex I membrane domain at 3.0 Å resolution. It includes six subunits, NuoL, NuoM, NuoN, NuoA, NuoJ and NuoK, with 55 transmembrane helices. The fold of the homologous antiporter-like subunits L, M and N is novel, with two inverted structural repeats of five transmembrane helices arranged, unusually, face-to-back. Each repeat includes a discontinuous transmembrane helix and forms half of a channel across the membrane. A network of conserved polar residues connects the two half-channels, completing the proton translocation pathway. Unexpectedly, lysines rather than carboxylate residues act as the main elements of the proton pump in these subunits. The fourth probable proton-translocation channel is at the interface of subunits N, K, J and A. The structure indicates that proton translocation in complex I, uniquely, involves coordinated conformational changes in six symmetrical structural elements. |
| Links |
PubMed Online version:10.1038/nature10330 |
| Keywords |
Antiporters/chemistry; Antiporters/metabolism; Cell Membrane/metabolism; Crystallography, X-Ray; Electron Transport Complex I/chemistry; Electron Transport Complex I/metabolism; Escherichia coli/chemistry; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/metabolism; Ion Transport; Lysine/metabolism; Models, Molecular; NAD/metabolism; NADH Dehydrogenase/chemistry; NADH Dehydrogenase/metabolism; Protein Binding; Protein Folding; Protein Structure, Tertiary; Protein Subunits/chemistry; Protein Subunits/metabolism; Protons; Ubiquinone/metabolism |
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