Molecular analysis of the ribosome recycling factor ABCE1 bound to the 30S post-splitting complex.

Elina Nürenberg‐Goloub,Hanna Kratzat,Peter Kötter,Roland Beckmann,Robert Tampé,Holger Heinemann,Otto Berninghausen,André Heuer,Thomas Becker

doi:10.15252/embj.2019103788

Elina Nürenberg‐Goloub, Hanna Kratzat + Show 7 more

Open Access

https://doi.org/10.15252/embj.2019103788

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Abstract

Ribosome recycling by the twin‐ATPase ABCE1 is a key regulatory process in mRNA translation and surveillance and in ribosome‐associated protein quality control in Eukarya and Archaea. Here, we captured the archaeal 30S ribosome post‐splitting complex at 2.8 Å resolution by cryo‐electron microscopy. The structure reveals the dynamic behavior of structural motifs unique to ABCE1, which ultimately leads to ribosome splitting. More specifically, we provide molecular details on how conformational rearrangements of the iron–sulfur cluster domain and hinge regions of ABCE1 are linked to closure of its nucleotide‐binding sites. The combination of mutational and functional analyses uncovers an intricate allosteric network between the ribosome, regulatory domains of ABCE1, and its two structurally and functionally asymmetric ATP‐binding sites. Based on these data, we propose a refined model of how signals from the ribosome are integrated into the ATPase cycle of ABCE1 to orchestrate ribosome recycling.

Highlights

Protein biosynthesis via mRNA translation is a fundamental process in living cells
The purified 30S-ABCE1IIEA post-SC was subjected to singleparticle cryogenic electron microscopy (cryo-EM) analysis. 3D classification revealed that the vast majority (97%) of 30S particles were associated with ABCE1IIEA
We observed that NBSI is in an active conformation with all residues needed for catalytic activity in place, i.e., activation of a water molecule for nucleophilic attack on the c-phosphate (Chen et al, 2003; Lammens et al, 2011; Hofmann et al, 2019)

Summary

Introduction

Translation is interlaced in a complex network of cellular pathways including mRNA surveillance, ribosome-associated quality control, and ribosome biogenesis (Bassler & Hurt, 2019; Joazeiro, 2019; Nurenberg-Goloub & Tampe, 2019). ABCE1 recycles canonical 70S/80S post-termination complexes (post-TCs) after stop codondependent termination and non-canonical post-TCs during mRNA surveillance and resumption of translation after cellular stress. In both cases, a decoding A-site factor (archaeal/eukaryotic release factor 1 (a/eRF1) or its homologue a/ePelota, respectively) is delivered to the ribosomal A-site by a translational GTPase (aEF1/eRF3 or aEF1/Hbs, respectively) and forms an interaction platform for ABCE1 to establish the 70S/80S pre-splitting complex (pre-SC; Becker et al, 2012; Preis et al, 2014; Brown et al, 2015; Shao et al, 2016).

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