title: ALS Mutations Disrupt Phase Separation Mediated by α-Helical Structure in the TDP-43 Low-Complexity C-Terminal Domain.
abstract: RNA-binding protein TDP-43 mediates essential RNA processing but forms cytoplasmic neuronal inclusions via its C-terminal domain (CTD) in amyotrophic lateral sclerosis (ALS). It remains unclear if aggregated TDP-43 is neurotoxic and if ∼50 ALS-associated missense mutations in TDP-43 CTD promote aggregation, or if loss of normal function plays a role in disease. Recent work points to the ability of related proteins to assemble into functional phase-separated ribonucleoprotein granules via their structurally disordered prion-like domains. Here, we provide atomic details on the structure and assembly of the low-complexity CTD of TDP-43 into liquid-liquid phase-separated in vitro granules and demonstrate that ALS-associated variants disrupt interactions within granules. Using nuclear magnetic resonance spectroscopy, simulation, and microscopy, we find that a subregion cooperatively but transiently folds into a helix that mediates TDP-43 phase separation. ALS-associated mutations disrupt phase separation by inhibiting interaction and helical stabilization. Therefore, ALS-associated mutations can disrupt TDP-43 interactions, affecting function beyond encouraging aggregation.
authors.affiliation: Graduate Program in Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI 02912, USA.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Conicella
authors.affiliation: Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA.
authors.forename: Gül H
authors.initials: GH
authors.lastname: Zerze
authors.affiliation: Department of Chemical and Biomolecular Engineering, Lehigh University, Bethlehem, PA 18015, USA.
authors.forename: Jeetain
authors.initials: J
authors.lastname: Mittal
authors.affiliation: Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI 02912, USA. Electronic address: nicolas_fawzi@brown.edu.
authors.forename: Nicolas L
authors.initials: NL
authors.lastname: Fawzi
mesh_terms: D020816:Amino Acid Motifs; D000690:Amyotrophic Lateral Sclerosis / Q000235:genetics / Q000473:pathology; D001665:Binding Sites; D003001:Cloning, Molecular; D003594:Cytoplasmic Granules / Q000737:chemistry* / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D009154:Mutation; D066329:Protein Aggregates; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D000072417:Protein Domains; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D066329:Protein Aggregates; D011994:Recombinant Proteins; C000598624:TARDBP protein, human