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Mol Cell. 2005 Jun 10;18(6):675-86.

Splitting of the posttermination ribosome into subunits by the concerted action of RRF and EF-G.

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1
Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Sweden.

Abstract

After peptide release by a class-1 release factor, the ribosomal subunits must be recycled back to initiation. We have demonstrated that the distance between a strong Shine-Dalgarno (SD) sequence and a codon in the P site is crucial for the binding stability of the deacylated tRNA in the P site of the posttermination ribosome and the in-frame maintenance of its mRNA. We show that the elongation factor EF-G and the ribosomal recycling factor RRF split the ribosome into subunits in the absence of initiation factor 3 (IF3) by a mechanism that requires both GTP and GTP hydrolysis. Taking into account that EF-G in the GTP form and RRF bind with positive cooperativity to the free 50S subunit but with negative cooperativity to the 70S ribosome, we suggest a mechanism for ribosome recycling that specifies distinct roles for EF-G, RRF, and IF3.

PMID:
15949442
DOI:
10.1016/j.molcel.2005.05.016
[Indexed for MEDLINE]
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