EMD-2764

Single-particle
3.75 Å
EMD-2764 Deposition: 26/08/2014
Map released: 05/11/2014
Last modified: 03/12/2014
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-2764

CryoEM structure of the 40S-eIF1-eIF1A preinitiation complex

EMD-2764

Single-particle
3.75 Å
EMD-2764 Deposition: 26/08/2014
Map released: 05/11/2014
Last modified: 03/12/2014
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Saccharomyces cerevisiae, Kluyveromyces lactis
Sample: 40S-eIF1-eIF1A preinitiation complex
Fitted models: 3j80 (Avg. Q-score: 0.352)

Deposition Authors: Hussain T , Llacer JL , Fernandez IS , Savva CG, Ramakrishnan V
Structural Changes Enable Start Codon Recognition by the Eukaryotic Translation Initiation Complex
Abstract:
During eukaryotic translation initiation, initiator tRNA does not insert fully into the P decoding site on the 40S ribosomal subunit. This conformation (POUT) is compatible with scanning mRNA for the AUG start codon. Base pairing with AUG is thought to promote isomerization to a more stable conformation (PIN) that arrests scanning and promotes dissociation of eIF1 from the 40S subunit. Here, we present a cryoEM reconstruction of a yeast preinitiation complex at 4.0 Å resolution with initiator tRNA in the PIN state, prior to eIF1 release. The structure reveals stabilization of the codon-anticodon duplex by the N-terminal tail of eIF1A, changes in the structure of eIF1 likely instrumental in its subsequent release, and changes in the conformation of eIF2. The mRNA traverses the entire mRNA cleft and makes connections to the regulatory domain of eIF2?, eIF1A, and ribosomal elements that allow recognition of context nucleotides surrounding the AUG codon.