A structural inventory of native ribosomal ABCE1-43S pre-initiation complexes.Kratzat, H., Mackens-Kiani, T., Ameismeier, M., Potocnjak, M., Cheng, J., Dacheux, E., Namane, A., Berninghausen, O., Herzog, F., Fromont-Racine, M., Becker, T., Beckmann, R.
(2021) EMBO J 40: e105179-e105179
- PubMed: 33289941
- DOI: https://doi.org/10.15252/embj.2020105179
- Primary Citation of Related Structures:
6ZCE, 6ZU9, 6ZVJ, 7A09, 7A1G
- PubMed 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.
Génétique des Interactions Macromoléculaires, UMR3525 CNRS, Institut Pasteur, Paris, France.