Structural insights into ribosomal rescue by Dom34 and Hbs1 at near-atomic resolution.

The surveillance of mRNA translation is imperative for homeostasis. Monitoring the integrity of the message is essential, as the translation of aberrant mRNAs leads to stalling of the translational machinery. During ribosomal rescue, arrested ribosomes are specifically recognized by the conserved eukaryotic proteins Dom34 and Hbs1, to initiate their recycling. ...
Here we solve the structure of Dom34 and Hbs1 bound to a yeast ribosome programmed with a nonstop mRNA at 3.3 A resolution using cryo-electron microscopy. The structure shows that Domain N of Dom34 is inserted into the upstream mRNA-binding groove via direct stacking interactions with conserved nucleotides of 18S rRNA. It senses the absence of mRNA at the A-site and part of the mRNA entry channel by direct competition. Thus, our analysis establishes the structural foundation for the recognition of aberrantly stalled 80S ribosomes by the Dom34·Hbs1·GTP complex during Dom34-mediated mRNA surveillance pathways.
Mesh Terms:
Cell Cycle Proteins, Cryoelectron Microscopy, Endoribonucleases, GTP-Binding Proteins, Guanylyl Imidodiphosphate, HSP70 Heat-Shock Proteins, Models, Molecular, Peptide Elongation Factors, Protein Domains, Protein Interaction Domains and Motifs, RNA, Fungal, RNA, Messenger, Recombinant Proteins, Ribosomes, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Static Electricity
Nat Commun
Date: Dec. 20, 2015
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