Cellular Prion Protein Conformational Shift after Liquid–Liquid Phase Separation Regulated by a Polymeric Antagonist and Mutations

• Published in: Journal of the American Chemical Society 2024-10, Vol.146 (40), p.27903-27914
• Main Authors: Liu, Yangyi, Tuttle, Marcus D., Kostylev, Mikhail A., Roseman, Graham P., Zilm, Kurt W., Strittmatter, Stephen M.
• Format: Article
• Language: English
• Subjects: antagonists; cognition; Humans; Maleates - chemistry; Maleates - pharmacology; Mutation; neurodegenerative diseases; Phase Separation; polymers; Prion Proteins - chemistry; Prion Proteins - genetics; Prion Proteins - metabolism; prions; Protein Conformation; PrPC Proteins - antagonists & inhibitors; PrPC Proteins - chemistry; PrPC Proteins - genetics; PrPC Proteins - metabolism; separation; Sulfonic Acids - chemistry
• ISSN: 0002-7863; 1520-5126; 1520-5126
• DOI: 10.1021/jacs.4c10590

Liquid–liquid phase separation (LLPS) of intrinsically disordered proteins has been associated with neurodegenerative diseases, although direct mechanisms are poorly defined. Here, we report on a maturation process for the cellular prion protein (PrPC) that involves a conformational change after LLPS and is regulated by mutations and poly­(4-styrenesulfonic acid-co-maleic acid) (PSCMA), a molecule that has been reported to rescue Alzheimer’s disease-related cognitive deficits by antagonizing the interaction between PrPC and amyloid-β oligomers (Aβo). We show that PSCMA can induce reentrant LLPS of PrPC and lower the saturation concentration (C sat) of PrPC by 100-fold. Regardless of the induction method, PrPC molecules subsequently undergo a maturation process to restrict molecular motion in a more solid-like state. The PSCMA-induced LLPS of PrPC stabilizes the intermediate LLPS conformational state detected by NMR, though the final matured β-sheet-rich state of PrPC is indistinguishable between induction conditions. The disease-associated E200 K mutation of PrPC also accelerates maturation. This post-LLPS shift in protein conformation and dynamics is a possible mechanism of LLPS-induced neurodegeneration.