Dynamic interaction network involving the conserved intrinsically disordered regions in human eIF5.

Area of Science:

• Molecular Biology
• Protein Dynamics
• Eukaryotic Gene Expression

Background:

• Eukaryotic translation initiation is a complex process involving multiple protein factors.
• The preinitiation complex (PIC) undergoes continuous remodeling.
• eIF2 delivers the initiator tRNA to the PIC, and eIF5 promotes GTP hydrolysis and eIF2 release.

Purpose of the Study:

• To investigate the dynamic interactions of intrinsically disordered regions (IDRs) within eIF5.
• To understand how these interactions contribute to preinitiation complex (PIC) remodeling.
• To elucidate the role of eIF5 phosphorylation in regulating translation initiation.

Main Methods:

• Analysis of intrinsically disordered regions (IDRs) in eIF5, including the DWEAR motif and C-terminal tail (CTT).
• Investigating dynamic contacts between eIF5's C-terminal domain (CTD) and its IDRs.
• Assessing the impact of eIF5 phosphorylation by CK2 on eIF5-eIF2 binding affinity.

Main Results:

• Two IDRs in eIF5, DWEAR and CTT, dynamically contact the eIF5-CTD and compete for binding.
• The eIF5-CTD•CTT interaction promotes eIF2β binding, while the eIF5-CTD•DWEAR interaction favors eIF1A binding.
• eIF5 phosphorylation by CK2 significantly increases eIF5 affinity for eIF2, and eIF2β has multiple eIF5-binding sites.

Conclusions:

• Intramolecular contact rearrangements in eIF5 are crucial for PIC remodeling during translation initiation.
• eIF5 phosphorylation by CK2 enhances eIF2 binding, potentially stimulating translation.
• The findings provide insights into the regulatory mechanisms of eukaryotic translation initiation.