What is it about?
Amyloidosis refers to a group of diseases in which proteins misfold and accumulate as insoluble fibrils in tissues. In transthyretin (TTR) amyloidosis, TTR forms fibrils that can deposit in organs such as the heart, peripheral nerves, and brain. While even normal TTR can form fibrils, disease-associated mutations often destabilize the protein, making fibril formation more likely. One therapeutic strategy is to use small molecules that bind and stabilize TTR, helping prevent fibril formation. However, existing marketed stabilizers do not fully cover all disease manifestations, and there is currently no stabilizer approved for brain-related TTR amyloidosis, underscoring the need for improved molecules. Traditionally, TTR stabilizer design has relied heavily on X-ray crystallography, which provides high-resolution but static structural snapshots. Because protein function (and dysfunction) also depends on dynamic motions and flexibility, static structures can miss important mutation- and ligand-dependent changes. To address this, we applied two mass spectrometry (MS)-based structural techniques—hydrogen–deuterium exchange MS (HDX‑MS) and fast photochemical oxidation of proteins MS (FPOP‑MS)—to monitor how destabilizing mutations and stabilizing compounds reshape TTR structure and dynamics in solution. We show that these MS approaches detect conformational and flexibility changes that are not visible in X-ray crystal structures.
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Why is it important?
Current treatments that stabilize TTR provide meaningful benefit, but they do not address every clinical presentation, and effective options for brain-related TTR amyloidosis remain limited. Designing stabilizers with higher potency and broader therapeutic coverage requires understanding not only where a compound binds, but also how it changes the protein’s stability and motions—especially across different disease-causing mutants. Our results highlight a key challenge for drug discovery in TTR amyloidosis: different mutations can shift TTR into distinct conformational “states.” If a stabilizer is optimized using a one-size-fits-all structural snapshot, it may overlook mutation-specific behaviors that matter for efficacy. By adding HDX‑MS and FPOP‑MS to the toolbox, researchers can obtain a more complete, solution-phase picture of protein dynamics, helping prioritize compounds that truly stabilize the relevant disease-associated conformations. We suggest that incorporating MS-based structural methods alongside crystallography can support the development of mutation-informed (and potentially mutation-specific) TTR stabilizers.
Perspectives
A central takeaway from this work is that “seeing” TTR at atomic resolution is not always enough if we only see it in a single, frozen pose. Mutations linked to TTR amyloidosis can subtly—but meaningfully—alter the protein’s flexibility and conformational landscape, and stabilizing compounds can reshape that landscape in ways that are difficult to capture with crystallography alone. What stood out to us is that HDX‑MS and FPOP‑MS report on changes that are essentially invisible in static crystal structures. These approaches allowed us to track how mutations and ligands influence TTR behavior in solution, where the disease-relevant folding and stability decisions are made. Looking ahead, we believe that integrating MS-based structural dynamics into the drug discovery pipeline can help shift TTR stabilizer development toward a more mutation-aware design strategy. Ultimately, this could accelerate the discovery of more effective stabilizers, including candidates tailored to specific mutant conformations and potentially better suited to address under-served manifestations of the disease.
Salvador Ventura
Universitat Autonoma de Barcelona
Read the Original
This page is a summary of: Mass spectrometry footprinting reveals how kinetic stabilizers counteract transthyretin dynamics altered by pathogenic mutations, Proceedings of the National Academy of Sciences, December 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2519908122.
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