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Publication Abstract from PubMed

The cricket paralysis virus (CrPV) uses an internal ribosomal entry site (IRES) to hijack the ribosome. In a remarkable RNA-based mechanism involving neither initiation factor nor initiator tRNA, the CrPV IRES jumpstarts translation in the elongation phase from the ribosomal A site. Here, we present cryoelectron microscopy (cryo-EM) maps of 80SCrPV-STOPeRF1eRF3GMPPNP and 80SCrPV-STOPeRF1 complexes, revealing a previously unseen binding state of the IRES and directly rationalizing that an eEF2-dependent translocation of the IRES is required to allow the first A-site occupation. During this unusual translocation event, the IRES undergoes a pronounced conformational change to a more stretched conformation. At the same time, our structural analysis provides information about the binding modes of eRF1eRF3GMPPNP and eRF1 in a minimal system. It shows that neither eRF3 nor ABCE1 are required for the active conformation of eRF1 at the intersection between eukaryotic termination and recycling.

Cryo-EM of Ribosomal 80S Complexes with Termination Factors Reveals the Translocated Cricket Paralysis Virus IRES.,Muhs M, Hilal T, Mielke T, Skabkin MA, Sanbonmatsu KY, Pestova TV, Spahn CM Mol Cell. 2015 Feb 5;57(3):422-432. doi: 10.1016/j.molcel.2014.12.016. Epub 2015 , Jan 15. PMID:25601755^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.