Article
- The EMBO Journal (2008) 27, 1706 - 1717
- doi:10.1038/emboj.2008.99
Published online: 22 May 2008
Subject Category:
Complementary roles of initiation factor 1 and ribosome recycling factor in 70S ribosome splitting
Michael Y Pavlov1, Ayman Antoun1,a, Martin Lovmar1,b and Måns Ehrenberg1
- Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden
Correspondence to:
Måns Ehrenberg, Department of Cell and Molecular Biology, Biomedical Center, Uppsala University, Box 596, Husargatan 3, Uppsala 751 24, Sweden. Tel.:+46 18 471 4213; Fax: +46 18 471 4262; E-mail: ehrenberg@xray.bmc.uu.se
aPresent Address: Institute for Cancer Studies, University of Birmingham, Birmingham, UK
bPresent Address: CMB/Microbiology, University of Gothenburg, Gothenburg, Sweden
Received 22 February 2008; Accepted 28 April 2008
Abstract
We demonstrate that ribosomes containing a messenger RNA (mRNA) with a strong Shine–Dalgarno sequence are rapidly split into subunits by initiation factors 1 (IF1) and 3 (IF3), but slowly split by ribosome recycling factor (RRF) and elongation factor G (EF-G). Post-termination-like (PTL) ribosomes containing mRNA and a P-site-bound deacylated transfer RNA (tRNA) are split very rapidly by RRF and EF-G, but extremely slowly by IF1 and IF3. Vacant ribosomes are split by RRF/EF-G much more slowly than PTL ribosomes and by IF1/IF3 much more slowly than mRNA-containing ribosomes. These observations reveal complementary splitting of different ribosomal complexes by IF1/IF3 and RRF/EF-G, and suggest the existence of two major pathways for ribosome splitting into subunits in the living cell. We show that the identity of the deacylated tRNA in the PTL ribosome strongly affects the rate by which it is split by RRF/EF-G and that IF3 is involved in the mechanism of ribosome splitting by IF1/IF3 but not by RRF/EF-G. With support from our experimental data, we discuss the principally different mechanisms of ribosome splitting by IF1/IF3 and by RRF/EF-G.
Keywords:
- IF1,
- initiation factors,
- protein synthesis,
- ribosome recycling factor,
- RRF
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