Cross-talk between mitochondrial malate dehydrogenase and the cytochrome bc1 complex
Qiyu Wang1, Linda Yu, Chang-An Yu
1Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
The Journal of Biological Chemistry
|January 16, 2010
Summary
Mitochondrial malate dehydrogenase (MDH) interacts with the cytochrome bc(1) complex, enhancing the activity of both. This cross-talk suggests a regulatory role in mitochondrial energy production.
Area of Science:
- Biochemistry
- Molecular Biology
- Cellular Respiration
Background:
- The mitochondrial cytochrome bc(1) complex is crucial for cellular respiration.
- Interactions between respiratory chain complexes and metabolic enzymes are not fully understood.
Purpose of the Study:
- To investigate interactions between the mitochondrial cytochrome bc(1) complex and matrix-soluble proteins.
- To elucidate the functional consequences of these interactions on enzyme activities.
Main Methods:
- Precipitation pulldown assay using purified cytochrome bc(1) complex and mitochondrial matrix proteins.
- Mass spectrometry (MALDI-TOF) and Western blotting for protein identification.
- Cross-linking technique to identify interaction sites.
- Enzyme activity assays for cytochrome bc(1) complex and malate dehydrogenase (MDH).
Main Results:
- Mitochondrial malate dehydrogenase (MDH) was identified as a protein interacting with the cytochrome bc(1) complex.
- Subunits I, II (core I and II), and V of the bc(1) complex were identified as MDH interaction sites.
- Incubation of MDH with the bc(1) complex increased the activities of both enzymes.
- The regulatory effect of the bc(1) complex on MDH activity was unidirectional.
Conclusions:
- A novel interaction and functional cross-talk exist between a citric acid cycle enzyme (MDH) and an electron transfer chain complex (cytochrome bc(1) complex).
- This interaction may play a regulatory role in mitochondrial bioenergetics and metabolic control.
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