Cryo-EM visualization of the ribosome in termination complex with apo-RF3 and RF1
Jesper Pallesen,
Yaser Hashem,
Gürkan Korkmaz,
Ravi Kiran Koripella,
Chenhui Huang,
Måns Ehrenberg,
Suparna Sanyal,
Joachim Frank
Affiliations
Jesper Pallesen
Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York City, United States
Yaser Hashem
Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York City, United States
Gürkan Korkmaz
Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
Ravi Kiran Koripella
Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
Chenhui Huang
Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
Måns Ehrenberg
Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
Suparna Sanyal
Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
Joachim Frank
Department of Biochemistry and Molecular Biophysics, Howard Hughes Medical Institute, Columbia University, New York City, United States; Department of Biological Sciences, Columbia University, New York City, United States
Termination of messenger RNA translation in Bacteria and Archaea is initiated by release factors (RFs) 1 or 2 recognizing a stop codon in the ribosomal A site and releasing the peptide from the P-site transfer RNA. After release, RF-dissociation is facilitated by the G-protein RF3. Structures of ribosomal complexes with RF1 or RF2 alone or with RF3 alone—RF3 bound to a non-hydrolyzable GTP-analog—have been reported. Here, we present the cryo-EM structure of a post-termination ribosome containing both apo-RF3 and RF1. The conformation of RF3 is distinct from those of free RF3•GDP and ribosome-bound RF3•GDP(C/N)P. Furthermore, the conformation of RF1 differs from those observed in RF3-lacking ribosomal complexes. Our study provides structural keys to the mechanism of guanine nucleotide exchange on RF3 and to an L12-mediated ribosomal recruitment of RF3. In conjunction with previous observations, our data provide the foundation to structurally characterize the complete action cycle of the G-protein RF3.
