HspB8 prevents aberrant phase transitions of FUS by chaperoning its folded RNA-binding domain

Elife. 2021 Sep 6;10:e69377. doi: 10.7554/eLife.69377.

Abstract

Aberrant liquid-to-solid phase transitions of biomolecular condensates have been linked to various neurodegenerative diseases. However, the underlying molecular interactions that drive aging remain enigmatic. Here, we develop quantitative time-resolved crosslinking mass spectrometry to monitor protein interactions and dynamics inside condensates formed by the protein fused in sarcoma (FUS). We identify misfolding of the RNA recognition motif of FUS as a key driver of condensate aging. We demonstrate that the small heat shock protein HspB8 partitions into FUS condensates via its intrinsically disordered domain and prevents condensate hardening via condensate-specific interactions that are mediated by its α-crystallin domain (αCD). These αCD-mediated interactions are altered in a disease-associated mutant of HspB8, which abrogates the ability of HspB8 to prevent condensate hardening. We propose that stabilizing aggregation-prone folded RNA-binding domains inside condensates by molecular chaperones may be a general mechanism to prevent aberrant phase transitions.

Keywords: FUS; RRM; aging; biochemistry; chaperones; chemical biology; human; molecular condensates; time-resolved quantitative XL-MS.

Publication types

  • Research Support, Non-U.S. Gov't
  • Video-Audio Media

MeSH terms

  • HeLa Cells
  • Heat-Shock Proteins / chemistry
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism*
  • Humans
  • Molecular Chaperones / chemistry
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism*
  • Mutation
  • Protein Binding
  • Protein Folding
  • Protein Interaction Domains and Motifs
  • Protein Stability
  • RNA / metabolism*
  • RNA-Binding Protein FUS / chemistry
  • RNA-Binding Protein FUS / genetics
  • RNA-Binding Protein FUS / metabolism*
  • Structure-Activity Relationship
  • Time Factors

Substances

  • FUS protein, human
  • HSPB8 protein, human
  • Heat-Shock Proteins
  • Molecular Chaperones
  • RNA-Binding Protein FUS
  • RNA

Grant support

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.