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bioRxiv · 10.1101/2021.12.09.471821

eIF5B and eIF1A remodel human translation initiation complexes to mediate ribosomal subunit joining

Lapointe, C. P.·Grosely, R.·Sokabe, M.·Alvarado, C.·Wang, J.·Montabana, E.·Villa, N.·Shin, B.-S.·Dever, T. E.·Fraser, C. S.·Fernandez, I. S.·Puglisi, J. D.
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Abstract

Joining of the ribosomal subunits at a translation start site on a messenger RNA during initiation commits the ribosome to synthesize a protein. Here, we combined single-molecule spectroscopy and structural methods using an in vitro reconstituted system to examine how the human ribosomal subunits join. Single-molecule fluorescence revealed when universally-conserved eukaryotic initiation factors (eIFs) eIF1A and eIF5B associate with and depart from initiation complexes. Guided by single-molecule dynamics, we examined initiation complexes that contained both eIF1A and eIF5B using single-particle electron cryo-microscopy. The resulting structure illuminated how eukaryote-specific contacts between eIF1A and eIF5B remodel the initiation complex to orient initiator tRNA in a conformation compatible with ribosomal subunit joining. Collectively, our findings provide a quantitative and architectural framework for the molecular choreography orchestrated by eIF1A and eIF5B during human translation initiation.

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Lapointe, C. P., Grosely, R., Sokabe, M., Alvarado, C., Wang, J., Montabana, E., Villa, N., Shin, B.-S., Dever, T. E., Fraser, C. S., Fernandez, I. S., Puglisi, J. D.. 2021-12-09. eIF5B and eIF1A remodel human translation initiation complexes to mediate ribosomal subunit joining. https://doi.org/10.1101/2021.12.09.471821

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