Send to

Choose Destination
Proc Natl Acad Sci U S A. 2013 Sep 24;110(39):15656-61. doi: 10.1073/pnas.1309578110. Epub 2013 Sep 12.

Involvement of protein IF2 N domain in ribosomal subunit joining revealed from architecture and function of the full-length initiation factor.

Author information

Centre for Integrative Biology, Department of Integrated Structural Biology, Institute of Genetics and of Molecular and Cellular Biology, Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche 7104, Institut National de la Santé de la Recherche Médicale U964, Université de Strasbourg, 67404 Illkirch, France.


Translation initiation factor 2 (IF2) promotes 30S initiation complex (IC) formation and 50S subunit joining, which produces the 70S IC. The architecture of full-length IF2, determined by small angle X-ray diffraction and cryo electron microscopy, reveals a more extended conformation of IF2 in solution and on the ribosome than in the crystal. The N-terminal domain is only partially visible in the 30S IC, but in the 70S IC, it stabilizes interactions between IF2 and the L7/L12 stalk of the 50S, and on its deletion, proper N-formyl-methionyl(fMet)-tRNA(fMet) positioning and efficient transpeptidation are affected. Accordingly, fast kinetics and single-molecule fluorescence data indicate that the N terminus promotes 70S IC formation by stabilizing the productive sampling of the 50S subunit during 30S IC joining. Together, our data highlight the dynamics of IF2-dependent ribosomal subunit joining and the role played by the N terminus of IF2 in this process.


integrated structural biology; protein synthesis

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center