Post-termination complex disassembly by ribosome recycling factor, a functional tRNA mimic

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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.