3JAP

Structure of a partial yeast 48S preinitiation complex in closed conformation

Summary for 3JAP

• Entry DOI: 10.2210/pdb3jap/pdb
• Related: 3J81 3JAM 3JAQ
• EMDB information: 3047 3048 3049
• Descriptor: Met-tRNAi (U31:A39 variant), eS6, eS7, ... (51 entities in total)
• Functional Keywords: eukaryotic translation initiation, 48s, small ribosome subunit, 40s, 43s, translation
• Biological source: Saccharomyces cerevisiae (yeast); More
• Total number of polymer chains: 47
• Total formula weight: 1546901.37

Authors

Llacer, J.L.,Hussain, T.,Ramakrishnan, V. (deposition date: 2015-06-18, release date: 2015-08-12, Last modification date: 2024-02-21)

Primary citation

Llacer, J.L.,Hussain, T.,Marler, L.,Aitken, C.E.,Thakur, A.,Lorsch, J.R.,Hinnebusch, A.G.,Ramakrishnan, V.
Conformational Differences between Open and Closed States of the Eukaryotic Translation Initiation Complex.
Mol.Cell, 59:399-412, 2015

PubMed Abstract: Translation initiation in eukaryotes begins with the formation of a pre-initiation complex (PIC) containing the 40S ribosomal subunit, eIF1, eIF1A, eIF3, ternary complex (eIF2-GTP-Met-tRNAi), and eIF5. The PIC, in an open conformation, attaches to the 5' end of the mRNA and scans to locate the start codon, whereupon it closes to arrest scanning. We present single particle cryo-electron microscopy (cryo-EM) reconstructions of 48S PICs from yeast in these open and closed states, at 6.0 Å and 4.9 Å, respectively. These reconstructions show eIF2β as well as a configuration of eIF3 that appears to encircle the 40S, occupying part of the subunit interface. Comparison of the complexes reveals a large conformational change in the 40S head from an open mRNA latch conformation to a closed one that constricts the mRNA entry channel and narrows the P site to enclose tRNAi, thus elucidating key events in start codon recognition.

PubMed: 26212456
DOI: 10.1016/j.molcel.2015.06.033

Experimental method

ELECTRON MICROSCOPY (4.9 Å)