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Mutually cooperative binding of eukaryotic translation initiation factor (eIF) 3 and eIF4A to human eIF4G-1
N L Korneeva1, B J Lamphear, F L Hennigan
1Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932, USA.
The Journal of Biological Chemistry
|October 7, 2000
Summary
Eukaryotic translation initiation factor 4G-1 (eIF4G) binds eIF3 and eIF4A. The eIF3-binding site is within residues 975-1078 and does not overlap RNA-binding sites, suggesting direct interaction. Binding is mutually cooperative.
Area of Science:
- Molecular Biology
- Protein-Protein Interactions
- Gene Expression Regulation
Background:
- Eukaryotic translation initiation factor 4G-1 (eIF4G) is essential for mRNA recruitment to the 43 S preinitiation complex.
- The central region of eIF4G interacts with eIF4A, eIF3, and RNA, playing a key role in translation initiation.
Purpose of the Study:
- To characterize the binding properties of the central region of human eIF4G.
- To determine the stoichiometry and kinetics of eIF3 binding to eIF4G.
- To investigate the interplay between eIF3, eIF4A, and RNA binding within eIF4G.
Main Methods:
- Titration and competition experiments to assess binding stoichiometry.
- Surface plasmon resonance (SPR) to analyze binding kinetics and affinity.
- Site-directed mutagenesis or fragment analysis to map binding regions.
Main Results:
- eIF3 binds the central region of eIF4G with 1:1 stoichiometry.
- The eIF3-binding region is localized to amino acid residues 975-1078.
- eIF3 binding to eIF4G is enhanced 4-fold by eIF4A, and eIF4A binding is enhanced 2.4-fold by eIF3, indicating mutual cooperation.
- The eIF3-binding site does not overlap with the RNA-binding site.
Conclusions:
- The eIF3-binding region within eIF4G (residues 975-1078) is distinct from the RNA-binding site, suggesting direct eIF3-eIF4G interaction.
- Cooperative binding between eIF3 and eIF4A to eIF4G enhances their interaction, potentially optimizing translation initiation complex formation.