Functional mapping of ribosome-contact sites in the ribosome recycling factor: a structural view from a tRNA mimic.

Ribosome recycling factor (RRF) is required for disassembly of the posttermination complex of the ribosome after release of polypeptides. The crystal structure of RRF resembles a tRNA shape, with an architecturally different flexibility compared with tRNA, but its structure-and-function relationships are unknown. We here found that an RRF variant defective in ribosome binding regains the binding capacity through 20 independent secondary changes occurring in three topologically distinct regions of RRF. Because two of these regions are equivalent to the tip of the anticodon stem and the upper surface of the acceptor stem of tRNA, RRF may interact with the ribosome in a way similar to tRNA, spanning 30S and 50S subunits, to exert its action for splitting the ribosome.