Structural view on recycling of archaeal and eukaryotic ribosomes after canonical termination and ribosome rescue

Ribosome recycling usually occurs after canonical termination triggered by a stop codon. Additionally, ribosomes that are stalled by aberrant mRNAs need to be recognized and subsequently recycled. In eukaryotes and archaea, the factors involved in canonical termination and ribosome rescue are structurally and functionally related. Both termination and ribosome rescue are mediated by class I release factors (eRF1/aRF1 in eukaryotic/archaeal termination) or their paralogs (Pelota/aPelota for ribosome rescue) and homologs of translational GTPases (eRF3/aEF1α in termination, Hbs1/aEF1α in ribosome rescue). These events are followed by recycling of the ribosome. Recently the ATPase ABCE1 was shown to be the main ribosome recycling factor. In concert with eRF1 or Pelota, ABCE1 dissociates the ribosome into subunits. During the past two years, several structures of ribosome rescue and ribosome recycling complexes have been solved by cryo-electron microscopy and crystallography. These structures along with recent functional data make it possible to propose a molecular model of these late translation events in termination and recycling.

► ABCE1 is essential for eukaryotic and archaeal ribosome recycling.
► ABCE1 has been shown to be involved in recycling after canonical termination as well as ribosome rescue.
► Recent crystal and cryo-EM structures provide insights into mechanical action of ABCE1 to promote ribosome dissociation.
► ABCE1 is likely to be involved in linking termination and recycling to re-initiation.