Understanding Phase Separation Characteristics of Nonamyloid β-component of α-Synuclein

Abstract

Biomolecular condensates are membrane-less assemblies consisting of proteins and nucleic acids. Altered protein dynamics can however lead to pathogenic condensates linked to several neurodegenerative diseases. Numerous studies have reported Liquid-Liquid Phase Separation (LLPS) to be the key mechanism resulting in the formation of biomolecular condensates. During LLPS, a homogeneous mixture spontaneously separates into a dilute and a dense phase and coexist. Multivalent interactions of Intrinsically Disordered Proteins (IDPs) are major drivers of phase separation. α-Synuclein is an IDP consisting of 140-residues whose aggregated states are associated with Parkinson’s disease. It consists of a non-amyloid β-component (NAC) region (residues 61-95) which is prone to beta sheet formation. Available data suggest that NAC plays a crucial role in the formation of pathogenic condensates. In this work, we have employed all-atom molecular dynamic simulations to investigate the phase behaviour of NAC region in water. Temperature replica exchange molecular dynamics simulations have also been performed to explore the phase change characteristics of NAC. This study will aid in further understanding the role of different domains of α-Synuclein in phase separation