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Structural features of human initiation factor 4E, studied by X-ray crystal analyses and molecular dynamics
Koji Tomoo1, Xu Shen, Koumei Okabe
1Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan. tomoo@gly.oups.ac.jp
Journal of Molecular Biology
|April 15, 2003
Summary
Structural analysis of human eukaryotic initiation factor 4E (eIF4E) reveals its cap-binding pocket
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Human eukaryotic initiation factor 4E (eIF4E) is crucial for cap-dependent translation initiation.
- Understanding eIF4E structure is key to deciphering its regulatory mechanisms.
Purpose of the Study:
- To elucidate the detailed structural features of human eIF4E in its cap-free and cap-bound states.
- To investigate the impact of Ser209 phosphorylation on eIF4E structure and function.
Main Methods:
- X-ray crystallography of eIF4E-cap analog complexes (m(7)GTP, m(7)GpppA).
- Molecular dynamics (MD) simulations of cap-free, cap-bound, and phosphorylated eIF4E.
- SDS-PAGE analysis to assess protein stability.
Main Results:
- Crystal structures reveal a temple-bell-shaped eIF4E with specific binding sites for the mRNA cap.
- MD simulations show increased flexibility and instability of the cap-binding pocket in cap-free eIF4E.
- Phosphorylation at Ser209 influences the cap-binding entrance size, suggesting a regulatory role.
Conclusions:
- eIF4E's structure is optimized for cap recognition, with distinct pockets for the base, triphosphate, and second nucleotide.
- Cap binding and phosphorylation confer structural stability and regulate eIF4E activity.
- These findings provide insights into translational control mechanisms.