Structural basis for the regulatory interactions of proapoptotic Par-4
Udaya K Tiruttani Subhramanyam1,2, Jan Kubicek2,3, Ulf B Eidhoff2
1Centre for Structural Systems Biology (CSSB), Hamburg, Germany.
Cell Death and Differentiation
|June 17, 2017
Summary
The proapoptotic protein Par-4 (partner and shaker-related cell death regulator) selectively induces cancer cell death. Its C-terminal domain structure reveals homodimerization and a masked nuclear export signal, influencing localization and apoptotic function.
Area of Science:
- Structural Biology
- Molecular Biology
- Cancer Research
Background:
- Partner and shaker-related cell death regulator (Par-4) is a proapoptotic protein.
- Par-4 selectively induces apoptosis in cancer cells, making it a potential therapeutic target.
Purpose of the Study:
- To determine the X-ray crystal structure of the C-terminal domain of Par-4 (Par-4CC).
- To elucidate the structural mechanisms regulating Par-4's apoptotic function and intracellular localization.
Main Methods:
- MAD phasing was used to obtain the X-ray crystal structure of Par-4CC.
- Homodimerization and heteromeric interaction models were employed to analyze structural features.
Main Results:
- Par-4CC forms a parallel coiled-coil homodimer structure.
- A nuclear export signal (Par-4NES) within Par-4CC is masked upon dimerization, suggesting a mechanism for nuclear localization.
- Charge interactions are critical for the stability of Par-4 leucine zipper (Par-4LZ) heteromers, which also exhibit NES masking capacity.
Conclusions:
- The determined structure of Par-4CC provides insights into its homodimerization and apoptotic regulation.
- Dimerization-dependent masking of the NES is a key mechanism influencing Par-4's intracellular localization.
- Understanding Par-4's structural dynamics and interactions is crucial for developing targeted cancer therapies.
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