Crystal structure of the ribosome recycling factor from Escherichia coli

We have determined the crystal structure of the Escherichia coli ribosome r ecycling factor (RRF), which catalyzes the disassembly of the termination c omplex in protein synthesis. The L-shaped molecule consists of two domains: a triple-stranded antiparallel coiled-coil and an alp domain. The coil dom ain has a cylindrical shape and negatively charged surface, which are remin iscent of the anticodon arm of tRNA and domain IV of elongation factor EF-G . We suggest that RRF binds to the ribosomal A-site through its coil domain , which is a tRNA mimic. The relative position of the two domains is change d about an axis along the hydrophobic cleft in the hinge where the alkyl ch ain of a detergent molecule is bound. The tRNA mimicry and the domain movem ent observed in RRF provide a structural basis for understanding the role o f RRF in protein synthesis.