Electrostatic and hydrophobic interactions of lipid-associated α-synuclein: The role of a water-limited interfaces in amyloid fibrillation

Human α‑synuclein (αSyn) is an intrinsically disordered protein (IDP) whose biological and pathological functions in brain neuronal cells have not yet been fully elucidated. αSyn intrinsically participates in aiding neurotransmitter trafficking through αSyn the association with lipid membranes. However, lipid-associated states of αSyn also induce amyloid self-assembly that is linked to the pathogenesis of various synucleinopathies. These contradicting actions arise from the limited water content near lipid-water interfaces that controls αSyn electrostatic and hydrophobic interactions. Thus, understanding the molecular interactions between αSyn and lipid membranes in the presence of water molecules is critical in elucidating the pivotal role of lipid-associated αSyn in amyloid self-assembly. In this review, we describe how the membrane interface controls electrostatic and hydrophobic interactions of lipid-associated αSyn. Moreover, membrane amyloid self-assembly of αSyn will be further discussed with regards to the structural dynamics of lipid-associated αSyn and water molecules near the interface. •Water-lipid interface provides water-limited condition which modulates electrostatic and hydrophobic interaction of IDPs.•Biological and pathological behaviors of lipid-associated αSyn are largely unknown.•Water molecules near lipid membranes play a crucial role in pathologic self-assembly of αSyn.