TY - JOUR
T1 - Structural changes enable start codon recognition by the eukaryotic translation initiation complex
AU - Hussain, Tanweer
AU - Llácer, Jose L.
AU - Fernández, Israel S.
AU - Munoz, Antonio
AU - Martin-Marcos, Pilar
AU - Savva, Christos G.
AU - Lorsch, Jon R.
AU - Hinnebusch, Alan G.
AU - Ramakrishnan, V.
N1 - Funding Information:
We are grateful to Shaoxia Chen and Greg McMullan for technical support with cryo-EM, Toby Darling and Jake Grimmett for help with computing, Xiao-Chen Bai and Sjors H.W. Scheres for help and advice with EM data processing, and Garib Murshudov and Alan Brown for help with refinement of the atomic coordinates. We also thank Fan Zhang for providing the purified Sui3-2 mutant of eIF2, Jinsheng Dong for sharing his genetic findings on the U31:A39 tRNA i variant prior to publication, Ann Kelley and Sarah Walker for providing reagents and advice, and Thomas Dever for his insightful suggestion to employ Sui − variants. T.H. and J.L.L. were, respectively, supported by postdoctoral fellowships from EMBO and FEBS. This work was funded by grants to V.R. from the UK Medical Research Council (MC_U105184332), Wellcome Trust Senior Investigator award (WT096570), the Agouron Institute and the Jeantet Foundation, from the NIH (GM62128) previously to J.R.L., and from the Human Frontiers in Science Program (RGP-0028/2009) to A.G.H., J.R.L., and V.R., and by the Intramural Research Program of the NIH (A.G.H., P.M.-M., J.R.L., and A.M.).
Publisher Copyright:
© 2014 The Authors.
PY - 2014/10/23
Y1 - 2014/10/23
N2 - 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 eIF2α, eIF1A, and ribosomal elements that allow recognition of context nucleotides surrounding the AUG codon.
AB - 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 eIF2α, eIF1A, and ribosomal elements that allow recognition of context nucleotides surrounding the AUG codon.
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U2 - 10.1016/j.cell.2014.10.001
DO - 10.1016/j.cell.2014.10.001
M3 - Article
C2 - 25417110
AN - SCOPUS:84908332647
SN - 0092-8674
VL - 159
SP - 597
EP - 607
JO - Cell
JF - Cell
IS - 3
ER -