Structural insights into the nucleic acid remodeling mechanisms of the yeast THO-Sub2 complex.

Sandra K Schuller,Jan M Schuller,J Rajan Prabu,Fabien Bonneau,Marc Baumgärtner,Elena Conti,Jérôme Basquin

doi:10.7554/elife.61467

Abstract

The yeast THO complex is recruited to active genes and interacts with the RNA-dependent ATPase Sub2 to facilitate the formation of mature export-competent messenger ribonucleoprotein particles and to prevent the co-transcriptional formation of RNA:DNA-hybrid-containing structures. How THO-containing complexes function at the mechanistic level is unclear. Here, we elucidated a 3.4 Å resolution structure of Saccharomyces cerevisiae THO-Sub2 by cryo-electron microscopy. THO subunits Tho2 and Hpr1 intertwine to form a platform that is bound by Mft1, Thp2, and Tex1. The resulting complex homodimerizes in an asymmetric fashion, with a Sub2 molecule attached to each protomer. The homodimerization interfaces serve as a fulcrum for a seesaw-like movement concomitant with conformational changes of the Sub2 ATPase. The overall structural architecture and topology suggest the molecular mechanisms of nucleic acid remodeling during mRNA biogenesis.

Highlights

The biogenesis of eukaryotic mRNAs in the cell nucleus is an elaborate, multi-step process
The mature messenger ribonucleoprotein particle (mRNP) is shuttled through the nuclear pore to the cytoplasm via specific export factors (Moore and Proudfoot, 2009; Muller-McNicoll and Neugebauer, 2013; Rondon et al, 2010; Wende et al, 2019; Xie and Ren, 2019)
We identify the molecular mechanisms utilized by yeast THO to activate the unwinding properties of the Sub2 ATPase, thereby intimating how THO-containing complexes can fulfil their functions in R loop prevention and mRNP formation

Summary

Introduction

The biogenesis of eukaryotic mRNAs in the cell nucleus is an elaborate, multi-step process. Yra harbors potent RNA:RNA annealing activity (Portman et al, 1997) Data from both yeast and human studies have converged on the notion that THO binds Sub, which in turn recruits Yra to form the TREX complex (Heath et al, 2016; Strasser et al, 2002; Wende et al, 2019; Zenklusen et al, 2002). We identify the molecular mechanisms utilized by yeast THO to activate the unwinding properties of the Sub ATPase, thereby intimating how THO-containing complexes can fulfil their functions in R loop prevention and mRNP formation

Results and discussion

Materials and methods

Funding Funder European Commission