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The architecture of respiratory complex I
Rouslan G Efremov1, Rozbeh Baradaran, Leonid A Sazanov
1Medical Research Council Mitochondrial Biology Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK.
Nature
|May 28, 2010
Summary
Researchers elucidated the structure of complex I, a key enzyme in cellular energy production. The findings reveal a novel mechanism for proton translocation, potentially impacting neurodegenerative disease research.
Area of Science:
- Biochemistry
- Structural Biology
- Cellular Respiration
Background:
- Complex I is crucial for cellular energy production and proton translocation.
- Its dysfunction is linked to human neurodegenerative diseases.
- Previous studies determined the structure of its hydrophilic domain.
Purpose of the Study:
- To determine the alpha-helical structure of the membrane domain of complex I from Escherichia coli.
- To determine the structure of the entire complex I from Thermus thermophilus.
- To elucidate the mechanism of proton translocation in complex I.
Main Methods:
- X-ray crystallography at 3.9 A and 4.5 A resolution.
- Determination of the membrane domain structure of E. coli complex I.
- Determination of the entire Thermus thermophilus complex I structure.
Main Results:
- The membrane domain of E. coli complex I features antiporter-like subunits (NuoL/M/N) with 14 conserved transmembrane helices.
- Subunit NuoL contains a unique 110-A long amphipathic alpha-helix.
- The L-shaped structure of Thermus thermophilus complex I reveals 63 transmembrane helices.
Conclusions:
- The complex I architecture suggests conformational changes drive proton translocation via a piston-like motion of the NuoL amphipathic helix.
- This motion likely tilts transmembrane helices, facilitating proton movement.
- Understanding this mechanism offers insights into energy production and disease.
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