Article
- The EMBO Journal (2007) 26, 3109 - 3123
- doi:10.1038/sj.emboj.7601751
Published online: 14 June 2007
Subject Category:
Position of eukaryotic initiation factor eIF5B on the 80S ribosome mapped by directed hydroxyl radical probing
Anett Unbehaun1, Assen Marintchev3, Ivan B Lomakin1, Tatyana Didenko1, Gerhard Wagner3, Christopher UT Hellen1 and Tatyana V Pestova1,2
- Department of Microbiology and Immunology, SUNY Downstate Medical Center, Brooklyn, NY, USA
- AN Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
Correspondence to:
Tatyana V Pestova, Department of Microbiology and Immunology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Box 44, Brooklyn, NY 11203, USA. Tel.: +1 718 221 6121; Fax: +1 718 270 2656; E-mail: tatyana.pestova@downstate.edu
Assen Marintchev, Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, MA 02115, USA. Tel.: +1 617 8181365; Fax: +1 617 4324383; E-mail: assen_marintchev@hms.harvard.edu
Received 22 February 2007; Accepted 16 May 2007
Abstract
Eukaryotic translation initiation factor eIF5B is a ribosome-dependent GTPase that mediates displacement of initiation factors from the 40S ribosomal subunit in 48S initiation complexes and joining of 40S and 60S subunits. Here, we determined eIF5B's position on 80S ribosomes by directed hydroxyl radical cleavage. In the resulting model, eIF5B is located in the intersubunit cleft of the 80S ribosome: domain 1 is positioned near the GTPase activating center of the 60S subunit, domain 2 interacts with the 40S subunit (helices 3, 5 and the base of helix 15 of 18S rRNA and ribosomal protein (rp) rpS23), domain 3 is sandwiched between subunits and directly contacts several ribosomal elements including Helix 95 of 28S rRNA and helix 44 of 18S rRNA, domain 4 is near the peptidyl-transferase center and its helical subdomain contacts rpL10E. The cleavage data also indicate that binding of eIF5B might induce conformational changes in both subunits, with ribosomal segments wrapping around the factor. Some of these changes could also occur upon binding of other translational GTPases, and may contribute to factor recognition.
Keywords:
- directed hydroxyl radical cleavage,
- eIF5B,
- ribosome,
- translation,
- translational GTPase
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