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Yeast Ataxin-2 Forms an Intracellular Condensate Required for the Inhibition of TORC1 Signaling during Respiratory Growth.

Authors
  • Yang, Yu-San1
  • Kato, Masato1
  • Wu, Xi1
  • Litsios, Athanasios2
  • Sutter, Benjamin M1
  • Wang, Yun1
  • Hsu, Chien-Hsiang3
  • Wood, N Ezgi4
  • Lemoff, Andrew1
  • Mirzaei, Hamid1
  • Heinemann, Matthias2
  • Tu, Benjamin P5
  • 1 Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
  • 2 Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen 9747AG, the Netherlands. , (Netherlands)
  • 3 Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94158, USA.
  • 4 Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
  • 5 Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Electronic address: [email protected]
Type
Published Article
Journal
Cell
Publication Date
Apr 18, 2019
Volume
177
Issue
3
Identifiers
DOI: 10.1016/j.cell.2019.02.043
PMID: 30982600
Source
Medline
Keywords
Language
English
License
Unknown

Abstract

Yeast ataxin-2, also known as Pbp1 (polyA binding protein-binding protein 1), is an intrinsically disordered protein implicated in stress granule formation, RNA biology, and neurodegenerative disease. To understand the endogenous function of this protein, we identify Pbp1 as a dedicated regulator of TORC1 signaling and autophagy under conditions that require mitochondrial respiration. Pbp1 binds to TORC1 specifically during respiratory growth, but utilizes an additional methionine-rich, low complexity (LC) region to inhibit TORC1. This LC region causes phase separation, forms reversible fibrils, and enables self-association into assemblies required for TORC1 inhibition. Mutants that weaken phase separation in vitro exhibit reduced capacity to inhibit TORC1 and induce autophagy. Loss of Pbp1 leads to mitochondrial dysfunction and reduced fitness during nutritional stress. Thus, Pbp1 forms a condensate in response to respiratory status to regulate TORC1 signaling. Copyright © 2019 Elsevier Inc. All rights reserved.

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