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Structural insights into initial and intermediate steps of the ribosome‐recycling process
Author(s) -
Yokoyama Takeshi,
Shaikh Tanvir R,
Iwakura Nobuhiro,
Kaji Hideko,
Kaji Akira,
Agrawal Rajendra K
Publication year - 2012
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/emboj.2012.22
Subject(s) - ribosome , biology , ribosomal rna , 50s , transfer rna , ribosomal protein , protein subunit , 30s , elongation factor , 23s ribosomal rna , microbiology and biotechnology , eukaryotic ribosome , eukaryotic small ribosomal subunit , translation (biology) , a site , biophysics , biochemistry , binding site , messenger rna , rna , gene
The ribosome‐recycling factor (RRF) and elongation factor‐G (EF‐G) disassemble the 70S post‐termination complex (PoTC) into mRNA, tRNA, and two ribosomal subunits. We have determined cryo‐electron microscopic structures of the PoTC·RRF complex, with and without EF‐G. We find that domain II of RRF initially interacts with universally conserved residues of the 23S rRNA helices 43 and 95, and protein L11 within the 50S ribosomal subunit. Upon EF‐G binding, both RRF and tRNA are driven towards the tRNA‐exit (E) site, with a large rotational movement of domain II of RRF towards the 30S ribosomal subunit. During this intermediate step of the recycling process, domain II of RRF and domain IV of EF‐G adopt hitherto unknown conformations. Furthermore, binding of EF‐G to the PoTC·RRF complex reverts the ribosome from ratcheted to unratcheted state. These results suggest that (i) the ribosomal intersubunit reorganizations upon RRF binding and subsequent EF‐G binding could be instrumental in destabilizing the PoTC and (ii) the modes of action of EF‐G during tRNA translocation and ribosome‐recycling steps are markedly different.