Structural insights into the nucleic acid remodeling mechanisms of the yeast THO-Sub2 complex
- Max Planck Institute of Biochemistry, Germany
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 mRNPs 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 3.4Å resolution structure of S. 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.
Data availability
Cryo-EM maps are available in the Electron Microscopy Data Bank (11859 and 11871). Atomic models are available in the Protein Data Bank (7APX and 7AQO).
Article and author information
Author details
Funding
European Commission (EXORICO)
- Elena Conti
Deutsche Forschungsgemeinschaft (201302640)
- Elena Conti
Deutsche Forschungsgemeinschaft (369799452)
- Elena Conti
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Schuller et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 2,642
- views
-
- 385
- downloads
-
- 32
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Structural insights into the nucleic acid remodeling mechanisms of the yeast THO-Sub2 complex
eLife 9:e61467.
https://doi.org/10.7554/eLife.61467
Further reading
-
- Structural Biology and Molecular Biophysics
Transition-state (TS) theory has provided the theoretical framework to explain the enormous rate accelerations of chemical reactions by enzymes. Given that proteins display large ensembles of conformations, unique TSs would pose a huge entropic bottleneck for enzyme catalysis. To shed light on this question, we studied the nature of the enzymatic TS for the phosphoryl-transfer step in adenylate kinase by quantum-mechanics/molecular-mechanics calculations. We find a structurally wide set of energetically equivalent configurations that lie along the reaction coordinate and hence a broad transition-state ensemble (TSE). A conformationally delocalized ensemble, including asymmetric TSs, is rooted in the macroscopic nature of the enzyme. The computational results are buttressed by enzyme kinetics experiments that confirm the decrease of the entropy of activation predicted from such wide TSE. TSEs as a key for efficient enzyme catalysis further boosts a unifying concept for protein folding and conformational transitions underlying protein function.
-
- Neuroscience
- Structural Biology and Molecular Biophysics
We present near-atomic-resolution cryoEM structures of the mammalian voltage-gated potassium channel Kv1.2 in open, C-type inactivated, toxin-blocked and sodium-bound states at 3.2 Å, 2.5 Å, 3.2 Å, and 2.9 Å. These structures, all obtained at nominally zero membrane potential in detergent micelles, reveal distinct ion-occupancy patterns in the selectivity filter. The first two structures are very similar to those reported in the related Shaker channel and the much-studied Kv1.2–2.1 chimeric channel. On the other hand, two new structures show unexpected patterns of ion occupancy. First, the toxin α-Dendrotoxin, like Charybdotoxin, is seen to attach to the negatively-charged channel outer mouth, and a lysine residue penetrates into the selectivity filter, with the terminal amine coordinated by carbonyls, partially disrupting the outermost ion-binding site. In the remainder of the filter two densities of bound ions are observed, rather than three as observed with other toxin-blocked Kv channels. Second, a structure of Kv1.2 in Na+ solution does not show collapse or destabilization of the selectivity filter, but instead shows an intact selectivity filter with ion density in each binding site. We also attempted to image the C-type inactivated Kv1.2 W366F channel in Na+ solution, but the protein conformation was seen to be highly variable and only a low-resolution structure could be obtained. These findings present new insights into the stability of the selectivity filter and the mechanism of toxin block of this intensively studied, voltage-gated potassium channel.
