Capturing the Conformational Ensemble of the Mixed Folded Polyglutamine Protein Ataxin-3

Alessandro Sicorello, Bartosz Różycki, Petr V. Konarev, Dmitri I. Svergun, Annalisa Pastore*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Ataxin-3 is a deubiquitinase involved in protein quality control and other essential cellular functions. It preferentially interacts with polyubiquitin chains of four or more units attached to proteins delivered to the ubiquitin-proteasome system. Ataxin-3 is composed of an N-terminal Josephin domain and a flexible C terminus that contains two or three ubiquitin-interacting motifs (UIMs) and a polyglutamine tract, which, when expanded beyond a threshold, leads to protein aggregation and misfolding and causes spinocerebellar ataxia type 3. The high-resolution structure of the Josephin domain is available, but the structural and dynamical heterogeneity of ataxin-3 has so far hindered the structural description of the full-length protein. Here, we characterize non-expanded and expanded variants of ataxin-3 in terms of conformational ensembles adopted by the proteins in solution by jointly using experimental data from nuclear magnetic resonance and small-angle X-ray scattering with coarse-grained simulations. Our results pave the way to a molecular understanding of polyubiquitin recognition.

Original languageEnglish
Pages (from-to)70-81.e5
JournalStructure
Volume29
Issue number1
DOIs
Publication statusPublished - 7 Jan 2021

Keywords

  • ensemble refinement
  • hybrid methods
  • intrinsically unfolded proteins
  • Monte Carlo simulations
  • neurodegeneration
  • NMR
  • polyglutamine
  • PRE
  • SAXS

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