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

• Main Authors: Arjun Prabhakar, Mark C. Capece, Alexey Petrov, Junhong Choi, Joseph D. Puglisi
• Format: Article
• Language: English
• Published: Elsevier 2017-07-01
• Series: Cell Reports
• Subjects: ribosome; translation; termination; stop codon; release factor; recycling; RRF; EF-G; IF3; single-molecule fluorescence
• Online Access: http://www.sciencedirect.com/science/article/pii/S2211124717308252

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.