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Visualization of ATP Synthase Dimers in Mitochondria by Electron Cryo-tomography
Published on: September 14, 2014
Dodecameric structure and ATPase activity of the human TIP48/TIP49 complex
Teena Puri1, Petra Wendler, Barbara Sigala
1Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, UK.
Journal of Molecular Biology
|December 13, 2006
Summary
The TIP48/TIP49 complex, crucial for cancer-related pathways, exhibits synergistic ATPase activity. Both TIP48 and TIP49 proteins are essential for ATP hydrolysis, with distinct biochemical roles revealed by structural analysis.
Area of Science:
- Biochemistry
- Molecular Biology
- Structural Biology
Background:
- TIP48 and TIP49 are conserved eukaryotic AAA(+) proteins involved in chromatin modification and cancer pathways.
- Their precise biochemical function and mechanism remain largely uncharacterized.
- They are known components of essential chromatin-modifying complexes.
Purpose of the Study:
- To investigate the biochemical activity and structure of the human TIP48/TIP49 complex.
- To elucidate the roles of TIP48 and TIP49 in ATP hydrolysis and potential DNA-related activities.
- To understand the structural basis for the complex's function.
Main Methods:
- Recombinant expression and purification of the human TIP48/TIP49 complex.
- In vitro biochemical assays to assess ATPase and DNA helicase/branch migration activities.
- Negative stain electron microscopy and 3D reconstruction to determine complex structure.
Main Results:
- The TIP48/TIP49 complex demonstrated synergistic ATPase activity, dependent on both proteins.
- No DNA helicase or branch migration activity was detected.
- 3D reconstruction revealed a unique structure of two stacked hexameric rings with distinct top and bottom rings.
- TIP48, but not TIP49, formed oligomers in the presence of adenine nucleotides.
Conclusions:
- The TIP48/TIP49 complex requires both subunits for ATP hydrolysis, indicating functional interdependence.
- Biochemical and structural differences between TIP48 and TIP49 likely contribute to specialized functions.
- The findings provide insights into the mechanism of this cancer-associated protein complex.
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