Eukaryotic translation initiation is controlled by cooperativity effects within ternary complexes of 4E-BP1, eIF4E, and the mRNA 5' cap

Abstract

Initiation is the rate-limiting step during mRNA 5' cap-dependent translation, and thus a target of a strict control in the eukaryotic cell. It is shown here by analytical ultracentrifugation and fluorescence spectroscopy that the affinity of the human translation inhibitor, eIF4E-binding protein (4E-BP1), to the translation initiation factor 4E is significantly higher when eIF4E is bound to the cap. The 4E-BP1 binding stabilizes the active eIF4E conformation and, on the other hand, can facilitate dissociation of eIF4E from the cap. These findings reveal the particular allosteric effects forming a thermodynamic cycle for the cooperative regulation of the translation initiation inhibition.

Keywords: 4E binding protein 1; 4E-BP1; 7-methylguanosine 5′-triphosphate; Analytical ultracentrifugation; DB; Fluorescence; SPR; TCEP; TFA; Translation initiation; dialysis buffer; eIF4E; eukaryotic initiation factor 4E; m(7)GTP; mRNA 5′cap; surface plasmon resonance; trifluoroacetic acid; tris (2-carboxyethyl) phosphine HCl.