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Visualization of ATP Synthase Dimers in Mitochondria by Electron Cryo-tomography
Published on: September 14, 2014
ATP induces a conformational change in lipid-bound cytochrome c
E K Tuominen1, K Zhu, C J Wallace
1Helsinki Biophysics and Biomembrane Group, Department of Medical Chemistry, Institute of Biomedicine, P.O. Box B8 (Siltavuorenpenger 10 A), University of Helsinki, FIN-00014 Helsinki, Finland.
The Journal of Biological Chemistry
|March 30, 2001
Summary
Adenosine triphosphate (ATP) binding induces conformational changes in lipid-bound cytochrome c (cyt c). These ATP-induced changes are mediated through a specific binding site involving Arg(91).
Area of Science:
- Biochemistry
- Biophysics
- Protein Science
Background:
- Cytochrome c (cyt c) is a protein involved in cellular respiration.
- Lipid-protein interactions play crucial roles in protein function and conformation.
- Adenosine triphosphate (ATP) is a key molecule in cellular energy transfer.
Purpose of the Study:
- To investigate the effect of ATP on the conformation of lipid-bound cytochrome c.
- To identify the specific binding site and residues involved in ATP-mediated conformational changes.
- To elucidate the mechanism of ATP-induced modulation of lipid-bound cyt c.
Main Methods:
- Resonance energy transfer studies using pyrene-labeled phospholipids and cytochrome c.
- Circular dichroism (CD) spectroscopy to detect conformational changes.
- Time-resolved spectroscopy with a fluorescent cyt c analog.
- Site-directed mutagenesis (Arg(91) to norleucine) to probe the binding site.
Main Results:
- ATP binding caused quenching of pyrene fluorescence, indicating conformational changes in lipid-bound cyt c.
- Circular dichroism confirmed ATP-induced conformational alterations in the Soret band region.
- A high-affinity ATP-binding site in cyt c was implicated, involving Arg(91).
- Mutation of Arg(91) to norleucine significantly reduced the ATP effect on lipid-bound cyt c.
Conclusions:
- ATP binding induces significant conformational changes in lipid-bound cytochrome c.
- The Arg(91) residue is crucial for the ATP-mediated modulation of lipid-bound cyt c.
- These findings highlight a specific ATP-binding site that influences cyt c's interaction with lipids.
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