Fig. 2: Stabilization of mRNA–tRNA by wybutosine modification of tRNAPhe, rearrangements of the decoding centre and depiction of a pawl function for eEF2 during translocation.
From: Accuracy mechanism of eukaryotic ribosome translocation
a, Wybutosine cross-strand stacks on the first codon–anticodon base pair formed by mRNA codon UUC and tRNAPhe at the ap/P state and stabilizes the last position of the adjacent upstream AUG codon (G3). An alternative view (bottom) of the same pattern clearly demonstrates how wybutosine enhances stabilization of mRNA to prevent a frame shift during translocation. b, Interactions between the backbones of translocating mRNA and decoding A1756 and A1757 of h44; mRNA in classical state is in grey. c, A shift of helix 69 (H69) of 25S rRNA is coupled to rearrangements of the decoding centre as compared to the bacterial classical state in white (PDB ID 4V6F). d, Contacts of eEF2 (coloured by domain) with LSU (grey), body (cyan) and head (pale cyan) of SSU; dashed squares indicate contacts that are disrupted at the late stage of translocation, allowing eEF2 to uncouple from the SSU body. e, Superposition of intermediate- and late (grey) (TI-POST-1, PDB ID 6GZ3)-translocation structures relative to LSU reveals eEF2 acting as a pawl anchoring and decoupling ap/P tRNA from the SSU head and body. The reverse direction of the SSU head and body rotation to a classical post-translocation state is indicated with arrows.
