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Hirokawa G, Kiel MC, Muto A, Selmer M, Raj V, Liljas A, Igarashi K, Kaji H, Kaji A. Post-termination complex disassembly by ribosome recycling factor, a functional tRNA mimic. EMBO J 2002; 21:2272-81. [PMID: 11980724 PMCID: PMC125990 DOI: 10.1093/emboj/21.9.2272] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ribosome recycling factor (RRF) together with elongation factor G (EF-G) disassembles the post- termination ribosomal complex. Inhibitors of translocation, thiostrepton, viomycin and aminoglycosides, inhibited the release of tRNA and mRNA from the post-termination complex. In contrast, fusidic acid and a GTP analog that fix EF-G to the ribosome, allowing one round of tRNA translocation, inhibited mRNA but not tRNA release from the complex. The release of tRNA is a prerequisite for mRNA release but partially takes place with EF-G alone. The data are consistent with the notion that RRF binds to the A-site and is translocated to the P-site, releasing deacylated tRNA from the P- and E-sites. The final step, the release of mRNA, is accompanied by the release of RRF and EF-G from the ribosome. With the model post-termination complex, 70S ribosomes were released from the post-termination complex by the RRF reaction and were then dissociated into subunits by IF3.
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Affiliation(s)
- Go Hirokawa
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Michael C. Kiel
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Aiko Muto
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Maria Selmer
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - V.Samuel Raj
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Anders Liljas
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Kazuei Igarashi
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Hideko Kaji
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
| | - Akira Kaji
- Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, Department of Biochemistry and Molecular Pharmacology, Jefferson Medical College, Thomas Jefferson University, Philadelphia, PA 19107, USA, Department of Clinical Biochemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan and Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, PO Box 124, SE-221 00 Lund, Sweden Corresponding author e-mail:
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Abstract
During the last decade, a new model for the ribosomal elongation cycle has emerged. It is based on the finding that eubacterial ribosomes possess 3 tRNA binding sites. More recently, this has been confirmed for archaebacterial and eukaryotic ribosomes as well, and thus appears to be a universal feature of the protein synthetic machinery. Ribosomes from organisms of all 3 kingdoms harbor, in addition to the classical P and A sites, an E site (E for exit), into which deacylated tRNA is displaced during translocation, and from which it is expelled by the binding of an aminoacyl-tRNA to the A site at the beginning of the subsequent elongation round. The main features of the allosteric 3-site model of ribosomal elongation are the following: first, the third tRNA binding site is located 'upstream' adjacent to the P site with respect to the messenger, ie on the 5'-side of the P site. Second, during translocation, deacylated tRNA does not leave the ribosome from the P site, but co-translocates from the P site to the E site--when peptidyl-tRNA translocates from the A site to the P site. Third, deacylated tRNA is tightly bound to the E site in the post-translocational state, where it undergoes codon--anticodon interaction. Fourth, the elongating ribosome oscillates between 2 main conformations: (i), the pre-translocational conformer, where aminoacyl-tRNA (or peptidyl-tRNA) and peptidyl-tRNA (or deacylated tRNA) are firmly bound to the A and P sites, respectively; and (ii), the post-translocational conformer, where peptidyl-tRNA and deacylated tRNA are firmly bound to the P and E sites, respectively. The transition between the 2 states is regulated in an allosteric manner via negative cooperatively. It is modulated in a symmetrical fashion by the 2 elongation factors Tu and G. An elongating ribosome always maintains 2 high-affinity tRNA binding sites with 2 adjacent codon--anticodon interactions. The allosteric transition from the post- to the pre-translocational state is involved in the accuracy of aminoacyl-tRNA selection, and the maintenance of 2 codon--anticodon interactions helps to keep the messenger in frame during translation.
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Affiliation(s)
- H J Rheinberger
- Max-Planck-Institut für Molekulare Genetik, Abteilung Wittmann, Berlin-Dahlem, Germany
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