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Electron transfer by domain movement in cytochrome bc1
Z Zhang1, L Huang, V M Shulmeister
1E. O. Lawrence Berkeley National Laboratory, University of California, 94720, USA.
Nature
|May 16, 1998
Summary
The cytochrome bc1 complex uses an iron-sulphur protein that moves to shuttle electrons. This movement is essential for transferring ubiquinol to cytochrome c1 in mitochondrial respiration.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- The cytochrome bc1 complex is a key enzyme in mitochondrial respiration.
- It facilitates electron transfer and generates an electrochemical gradient across the inner mitochondrial membrane.
Purpose of the Study:
- To elucidate the structural basis of electron transfer in the cytochrome bc1 complex.
- To investigate the mechanism of ubiquinol oxidation and cytochrome c reduction.
Main Methods:
- X-ray crystallography was used to determine the structure of the cytochrome bc1 complex from chicken, cow, and rabbit.
- Structures were obtained in the presence and absence of quinone oxidation inhibitors.
Main Results:
- Two distinct locations were identified for the extrinsic domain of the iron-sulphur protein.
- One location facilitates ubiquinol reduction, while the other facilitates cytochrome c1 oxidation.
- Neither location supports both reactions efficiently, suggesting a mobile mechanism.
Conclusions:
- The iron-sulphur protein's extrinsic domain moves to shuttle electrons from ubiquinol to cytochrome c1.
- This dynamic mechanism represents a novel mode of electron transfer in redox protein complexes.