Monday, August 8, 2011

Structure of a no-go mRNA decay complex bound to a stalled 80S ribosome

A recent work by the Beckmann group (University of Munich, Germany) published in Nature Structural and Molecular Biology describes a sub-nanometer cryo-EM reconstruction of a no-go mRNA decay complex bound to a stalled 80S ribosome. Homology models were manually docked into the density and further refined interactively with MDFF.

Structure of the no-go mRNA decay complex Dom34-Hbs1 bound to a stalled 80S ribosome.
Thomas Becker, Jean-Paul Armache, Alexander Jarasch, Andreas M Anger, Elizabeth Villa, Heidemarie Sieber, Basma Abdel Motaal, Thorsten Mielke, Otto Berninghausen, and Roland Beckmann. Nat. Struct. Mol. Biol., 18, 715-720, 2011.

No-go decay (NGD) is a mRNA quality-control mechanism in eukaryotic cells that leads to degradation of mRNAs stalled during translational elongation. The key factors triggering NGD are Dom34 and Hbs1. We used cryo-EM to visualize NGD intermediates resulting from binding of the Dom34–Hbs1 complex to stalled ribosomes. At subnanometer resolution, all domains of Dom34 and Hbs1 were identified, allowing the docking of crystal structures and homology models. Moreover, the close structural similarity of Dom34 and Hbs1 to eukaryotic release factors (eRFs) enabled us to propose a model for the ribosome-bound eRF1–eRF3 complex. Collectively, our data provide structural insights into how stalled mRNA is recognized on the ribosome and how the eRF complex can simultaneously recognize stop codons and catalyze peptide release.