ATP binding to lysozyme and superfolder GFP amyloid fibrils induces aggregate remodeling and attenuates their cytotoxicity.

The pathogenesis of neurodegenerative diseases such as Alzheimer's and Parkinson's, systemic and local amyloidoses is closely associated with amyloid fibril accumulation. Dysregulation of energy metabolism and a decline in the level of adenosine triphosphate (ATP), a key intracellular energy source and extracellular signaling molecule, contribute to the development of these pathologies. Despite the well-established role of ATP as a biological hydrotrope that prevents the initial aggregation of proteins, the impact of this nucleotide on the structure and properties of pre-formed (mature) amyloids is still poorly understood. In this study, we showed the ability of ATP to bind with affinity in the low-to-mid micromolar range to mature amyloids of lysozyme, which associated with hereditary lysozyme amyloidosis, and superfolder GFP, as model objects with unique properties, demonstrating a significant increase in the number of binding sites compared to native proteins. We demonstrated that this interaction induces declustering of both aggregate types, accompanied by fibril disordering specific to certain amyloidogenic proteins. Importantly, ATP-mediated fibril remodeling resulted in a significant reduction in their toxicity to mammalian cell lines, as well as a decrease in the aggregate resistance to chemical and thermal degradation. The obtained results reveal the complex nature of ATP's effects: while acting as an endogenous amyloid detoxification factor, it is also susceptible to sequestration in amyloid deposits due to its affinity in the low-to-mid micromolar range. Amyloid-associated ATP sequestration may lead to nucleotide deficiency and aggravation of amyloidosis.