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Cell Rep. 2017 Jul 5;20(1):161-172. doi: 10.1016/j.celrep.2017.06.028.

Post-termination Ribosome Intermediate Acts as the Gateway to Ribosome Recycling.

Author information

1
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Program in Biophysics, Stanford University, Stanford, CA 94305, USA.
2
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Chemistry, Stanford University, Stanford, CA 94305, USA.
3
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA.
4
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Applied Physics, Stanford University, Stanford, CA 94305, USA.
5
Department of Structural Biology, Stanford University School of Medicine, Stanford, CA 94305, USA. Electronic address: puglisi@stanford.edu.

Abstract

During termination of translation, the nascent peptide is first released from the ribosome, which must be subsequently disassembled into subunits in a process known as ribosome recycling. In bacteria, termination and recycling are mediated by the translation factors RF, RRF, EF-G, and IF3, but their precise roles have remained unclear. Here, we use single-molecule fluorescence to track the conformation and composition of the ribosome in real time during termination and recycling. Our results show that peptide release by RF induces a rotated ribosomal conformation. RRF binds to this rotated intermediate to form the substrate for EF-G that, in turn, catalyzes GTP-dependent subunit disassembly. After the 50S subunit departs, IF3 releases the deacylated tRNA from the 30S subunit, thus preventing reassembly of the 70S ribosome. Our findings reveal the post-termination rotated state as the crucial intermediate in the transition from termination to recycling.

KEYWORDS:

EF-G; IF3; RRF; recycling; release factor; ribosome; single-molecule fluorescence; stop codon; termination; translation

PMID:
28683310
PMCID:
PMC5555083
DOI:
10.1016/j.celrep.2017.06.028
[Indexed for MEDLINE]
Free PMC Article

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