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How does iron-sulfur cluster coordination regulate the activity of human glutaredoxin 2?
Carsten Berndt1, Christoph Hudemann, Eva-Maria Hanschmann
1The Medical Nobel Institute for Biochemistry, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
Antioxidants & Redox Signaling
|November 23, 2006
Summary
Human mitochondrial glutaredoxin 2 (Grx2) uses an iron-sulfur cluster as a redox sensor. Glutathione binding regulates Grx2 activity, dissociating the complex when glutathione is limited, revealing active Grx2.
Area of Science:
- Biochemistry
- Molecular Biology
- Oxidative Stress Research
Background:
- Human mitochondrial glutaredoxin 2 (Grx2) is the first identified iron-sulfur protein within the thioredoxin superfamily.
- The [2Fe-2S] cluster in Grx2 was hypothesized to function as a redox sensor, mediating activation during oxidative stress.
Purpose of the Study:
- To elucidate the structural and functional role of the iron-sulfur cluster in human Grx2.
- To investigate the mechanism of Grx2 activation by oxidative stress and the involvement of glutathione.
Main Methods:
- Biochemical assays to study protein complex formation and dissociation.
- Analysis of noncovalent binding interactions between Grx2, glutathione, and the iron-sulfur cluster.
Main Results:
- The [2Fe-2S] cluster is coordinated by N-terminal thiols from two Grx2 monomers and two glutathione molecules.
- Glutathione binding is noncovalent and exists in equilibrium with glutathione in solution.
- Dissociation of the holo-Grx2 complex occurs when reduced glutathione becomes a limiting factor, leading to the release of enzymatically active Grx2.
Conclusions:
- The iron-sulfur cluster and glutathione act as a regulatory switch for Grx2 activity.
- Grx2 activation is dependent on the availability of reduced glutathione, linking oxidative stress response to cellular glutathione levels.
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