An ALS ‐associated mutation in the C‐terminal α‐helix of TDP ‐43 uncouples condensate formation and amyloid assembly
Year: 2026
Type: article
Abstract: TAR DNA-binding protein 43 (TDP-43) plays a critical role in RNA metabolism and is incorporated into biomolecular condensates called stress granules. In amyotrophic lateral sclerosis (ALS) and several other neurodegenerative disorders, TDP-43 undergoes aberrant phase transitions, forming insoluble amyloid aggregates, including fibrils composed of solely its intrinsically disordered C-terminal domain (CTD). Despite its central role in disease, the conformational dynamics of the CTD remain poorly understood due to its heterogeneous and transient conformational landscape. Here, we employ native ion mobility-mass spectrometry (IM-MS) using nanopipette sub-micron nano electrospray ionization (nanoESI) emitters to characterize the conformational landscape of wild-type and ALS-associated TDP-43 CTD variants (Q331K and R361S) under different solution conditions. Our data suggest that mutations and salt concentration modulate the CTD's conformations. Combined with thioflavin T fluorescence, light scattering, and microscopy, we reveal that these conformational shifts correlate with altered amyloid assembly kinetics and propensity to form condensates. Notably, the Q331K variant, which has a mutation in the transient α-helical region in the CTD, has reduced propensity to form biomolecular condensates but can undergo amyloid assembly in the absence of condensate formation, suggesting that sequence alterations in this α-helical region can tune the molecular mechanism of amyloid assembly. This study demonstrates the power of IM-MS in probing disordered proteins and reveals mechanistic insights into how disease-associated mutations differentially tune TDP-43 CTD amyloid assembly mechanisms.
Source: Protein Science
DOI: 10.1002/pro.70565
Institution: University of Leeds
Language: English
Subfield: Neurology
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $4,480
Awards: New infrastructure for EM studies at the University of Leeds., G2667495944, Molecular grammar of SurA-client interactions in the periplasm of gram-negative bacteria, Probing biomolecular interactions by combining ETD-tandem mass spectrometry with chemical footprinting methodologies., G4538406725, Molecular basis of phase separation in viral replication and neurodegenerative disease, Unlocking the secrets of specialised ribosomes across eukaryotes
OpenAlex ID: W7154029090