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

Publication date: 5 July 2017
Source:Cell Reports, Volume 20, Issue 1
Author(s): Arjun Prabhakar, Mark C. Capece, Alexey Petrov, Junhong Choi, Joseph D. Puglisi
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.

Graphical abstract

Teaser

Ribosome intersubunit conformation plays a critical role in ribosome recycling after translation termination. Prabhakar et al. use single-molecule techniques to temporally resolve the post-termination intersubunit rotation that promotes factor-mediated disassembly of the ribosome. The observed ribosome conformational dynamics clarified the roles of the protein factors and timing of recycling events.


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