A multidisciplinary insight into the determinants of protein aggregation

Resumen

Chronic neurodegenerative disorders, the medical conditions that strike primarily mid- to late-life population, represent a major issue of modern society. Therefore, finding new diagnostic and therapeutic approaches to treat these disorders is a goal of increasing urgency. The neurodegenerative disorders are characterised by intra/extracellular protein misfolding, resulting in the formation of ordered aggregates that are responsible for the onset of these diseases. On the other hand, aggregation represents a major limitation in the industrial production of proteinaceous therapeutic agents. To elucidate the causes behind the formation of these insoluble deposits, the mechanisms by which they mediate cellular toxicity, and how evolution confronts this risk, we employed a multidisciplinary approach to study the determinants of aggregation reactions, using different protein models such as, amyloid β-peptide and α-synuclein. The research presented in this thesis seeks to understand the determinants of protein aggregation and its associated toxicity, in both the cellular environment and in vitro conditions, as well as to investigate how the selective pressure that acts to avoid the aggregation has shaped the cellular proteomes along the evolution. Implementing a novel structure-based bioinformatic tool, we identify the structural determinants of protein aggregation using bacteria as a model organism. Little is known about the structural determinants that drive the aggregation of a protein to a particular pathway, resulting in diverse aggregated macromolecular structures displaying different toxicity. Here, we address this issue using the Parkinson’s disease-associated intrinsically disordered protein, α-synuclein. Finally, using another intrinsically disordered protein, the amyloid β-peptide and mutants thereof, we identify the conformational species responsible for the cellular oxidative damage caused by the aggregation of this Alzheimer’s linked peptide, employing yeast as a model system. Overall, the work in this thesis attempts to understand fundamental aspects of protein aggregation processes, in both prokaryotic and eukaryotic organisms, highlighting how the interplay between different disciplines might improve our understanding of the impact of protein aggregation in health and disease.