Angelita Simonetti / Stefano Marzi / Isabelle M L Billas / Albert Tsai / Attilio Fabbretti / Alexander G Myasnikov / Pierre Roblin / Andrea C Vaiana / Isabelle Hazemann / Daniel Eiler / Thomas A Steitz / Joseph D Puglisi / Claudio O Gualerzi / Bruno P Klaholz /
PubMed 要旨
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 ...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.
EMDB-2448: Cryo-EM structure of T. thermophilus 30S Translation Initiation complex PDB-3j4j: Model of full-length T. thermophilus Translation Initiation Factor 2 refined against its cryo-EM density from a 30S Initiation Complex map 手法: EM (単粒子) / 解像度: 11.5 Å