Conformational dynamics of -synuclein during the interaction with phospholipid nanodiscs by Millisecond Hydrogen Deuterium Exchange Mass Spectrometry

Abstract

Both normal and pathological functions of -synuclein (SN), an abundant protein in the central and peripheral nervous system, have been linked to its interaction with membrane lipid bilayers. The ability to characterize structural transitions of SN upon membrane complexation will clarify molecular mechanisms associated with SN-linked pathologies, including Parkinsons disease (PD), Multiple Systems Atrophy and other synucleinopathies. In this work, Time-Resolved ElectroSpray Ionization Hydrogen/ Deuterium Exchange Mass Spectrometry (TRESI-HDX-MS) was employed to acquire a detailed picture of SNs conformational transitions as it undergoes complexation with nanodisc membrane mimics. Using this approach, SN interactions with DMPC nanodiscs were shown to be rapid exchanging and to have a little impact on the SN conformational ensemble. Interactions with nanodiscs containing lipids known to promote amyloidogenesis (e.g., POPG), on the other hand, were observed to induce substantial and specific changes in the SN conformational ensemble. Ultimately, we identify a region corresponding residues 19-28 and 45-57 of the SN sequence that is uniquely impacted by interactions with amyloidogenic lipid membranes and may therefore play a critical role in pathogenic aggregation.