Involvement of protein IF2 N domain in ribosomal subunit joining revealed from architecture and function of the full-length initiation factor.
Fiche publication
Date publication
septembre 2013
Journal
Proceedings of the National Academy of Sciences of the United States of America
Auteurs
Membres identifiés du Cancéropôle Est :
Dr KLAHOLZ Bruno, Dr SIMONETTI Angelita, Dr BILLAS Isabelle
Tous les auteurs :
Simonetti A, Marzi S, Billas IM, Tsai A, Fabbretti A, Myasnikov AG, Roblin P, Vaiana AC, Hazemann I, Eiler D, Steitz TA, Puglisi JD, Gualerzi CO, Klaholz BP
Lien Pubmed
Résumé
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.
Mots clés
integrated structural biology, protein synthesis
Référence
Proc. Natl. Acad. Sci. U.S.A.. 2013 Sep 24;110(39):15656-61