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 ...
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 80S⋅CrPV-STOP ⋅ eRF1 ⋅ eRF3 ⋅ GMPPNP and 80S⋅CrPV-STOP ⋅ eRF1 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 eRF1 ⋅ eRF3 ⋅ GMPPNP 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.
Organizational Affiliation:
Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA.,Institut für Medizinische Physik und Biophysik, Charite - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany.,Institut für Medizinische Physik und Biophysik, Charite - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany. Electronic address: christian.spahn@charite.de.,Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA; New Mexico Consortium, 4200 West Jemez Road, Suite 301, Los Alamos, NM 87544, USA.,Institut für Medizinische Physik und Biophysik, Charite - Universitätsmedizin Berlin, Charitéplatz 1, 10117 Berlin, Germany; UltraStrukturNetzwerk, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
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