TY - JOUR
T1 - Conformational Differences between Open and Closed States of the Eukaryotic Translation Initiation Complex
AU - Llácer, Jose L.
AU - Hussain, Tanweer
AU - Marler, Laura
AU - Aitken, Colin Echeverría
AU - Thakur, Anil
AU - Lorsch, Jon R.
AU - Hinnebusch, Alan G.
AU - Ramakrishnan, V.
N1 - Funding Information:
We are grateful to S. Chen, C.G. Savva, K.R. Vinothkumar, G. McMullan, and the staff of FEI for technical support with cryo-EM; T. Darling and J. Grimmett for help with computing; X.C. Bai and S.H.W. Scheres for advice with EM data processing; and G. Murshudov for help with refinement of the atomic coordinates. We also thank A. Kelley and I.S. Fernandez for providing reagents. J.L.L. and T.H. were, respectively, supported by postdoctoral fellowships from FEBS and EMBO. This work was funded by grants to from the UK Medical Research Council (MC_U105184332), Wellcome Trust Senior Investigator award (WT096570), the Agouron Institute and the Jeantet Foundation to V.R.; from the NIH (GM62128) formerly to J.R.L.; 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., J.R.L., and C.E.A.).
Publisher Copyright:
© 2015 The Authors.
PY - 2015/8/6
Y1 - 2015/8/6
N2 - 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 6.0Å and 4.9Å, 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.
AB - 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 6.0Å and 4.9Å, 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.
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U2 - 10.1016/j.molcel.2015.06.033
DO - 10.1016/j.molcel.2015.06.033
M3 - Article
C2 - 26212456
AN - SCOPUS:84938742519
SN - 1097-2765
VL - 59
SP - 399
EP - 412
JO - Molecular Cell
JF - Molecular Cell
IS - 3
ER -