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A structural inventory of native ribosomal ABCE1‐43S pre‐initiation complexes

Abstract : In eukaryotic translation, termination and ribosome recycling phases are linked to subsequent initiation of a new round of translation by persistence of several factors at ribosomal sub-complexes. These comprise/include the large eIF3 complex, eIF3j (Hcr1 in yeast) and the ATP-binding cassette protein ABCE1 (Rli1 in yeast). The ATPase is mainly active as a recycling factor, but it can remain bound to the dissociated 40S subunit until formation of the next 43S pre-initiation complexes. However, its functional role and native architectural context remains largely enigmatic. Here, we present an architectural inventory of native yeast and human ABCE1-containing pre-initiation complexes by cryo-EM. We found that ABCE1 was mostly associated with early 43S, but also with later 48S phases of initiation. It adopted a novel hybrid conformation of its nucleotide-binding domains, while interacting with the N-terminus of eIF3j. Further, eIF3j occupied the mRNA entry channel via its ultimate C-terminus providing a structural explanation for its antagonistic role with respect to mRNA binding. Overall, the native human samples provide a near-complete molecular picture of the architecture and sophisticated interaction network of the 43S-bound eIF3 complex and the eIF2 ternary complex containing the initiator tRNA.
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https://hal-pasteur.archives-ouvertes.fr/pasteur-03430600
Contributor : Christelle Lenormand Connect in order to contact the contributor
Submitted on : Tuesday, November 16, 2021 - 12:18:29 PM
Last modification on : Wednesday, November 17, 2021 - 4:01:33 AM

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Hanna Kratzat, Timur Mackens-Kiani, Michael Ameismeier, Mia Potocnjak, Jingdong Cheng, et al.. A structural inventory of native ribosomal ABCE1‐43S pre‐initiation complexes. EMBO Journal, EMBO Press, 2021, 40 (1), pp.e105179. ⟨10.15252/embj.2020105179⟩. ⟨pasteur-03430600⟩

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