Investigation of the interaction between the eukaryotic translation initiation factors eIF4G and eIF4AI

The eukaryotic translation initiation factor eIF4AI is the prototypical member of the DEAD‐box (DDX) family of ATP‐dependent RNA helicases, and RNA dependent ATPases. eIF4AI is critical for initiation of translation of mRNAs with highly structured 5′‐UTRs. It is recruited to eukaryotic mRNAs through interactions with eIF4G, which in turn is recruited to the cap structure of eukaryotic mRNAs by interactions with eIF4E. Together, these three proteins form the protein complex known as eIF4F. Of the more than 50 DDX proteins found in humans, eIF4A members possess unique amino acids conserved from yeast to human outside of the 9 conserved motifs that define the DDX family of proteins. These position were analyzed for their functional significance by producing recombinant eIF4A proteins with mutations at these positions, and these mutated proteins were tested for their enzymatic activity in the presence of recombinant eIF4G. Mutations of these unique residues in eIF4A have a significant impact on its functional interaction with eIF4G.