title: Oligomers of Parkinson's Disease-Related α-Synuclein Mutants Have Similar Structures but Distinctive Membrane Permeabilization Properties.
abstract: Single-amino acid mutations in the human α-synuclein (αS) protein are related to early onset Parkinson's disease (PD). In addition to the well-known A30P, A53T, and E46K mutants, recently a number of new familial disease-related αS mutations have been discovered. How these mutations affect the putative physiological function of αS and the disease pathology is still unknown. Here we focus on the H50Q and G51D familial mutants and show that like wild-type αS, H50Q and G51D monomers bind to negatively charged membranes, form soluble partially folded oligomers with an aggregation number of ~30 monomers under specific conditions, and can aggregate into amyloid fibrils. We systematically studied the ability of these isolated oligomers to permeabilize membranes composed of anionic phospholipids (DOPG) and membranes mimicking the mitochondrial phospholipid composition (CL:POPE:POPC) using a calcein release assay. Small-angle X-ray scattering studies of isolated oligomers show that oligomers formed from wild-type αS and the A30P, E46K, H50Q, G51D, and A53T disease-related mutants are composed of a similar number of monomers. However, although the binding affinity of the monomeric protein and the aggregation number of the oligomers formed under our specific protocol are comparable for wild-type αS and H50Q and G51D αS, G51D oligomers cannot disrupt negatively charged and physiologically relevant model membranes. Replacement of the membrane-immersed glycine with a negatively charged aspartic acid at position 51 apparently abrogates membrane destabilization, whereas a mutation in the proximal but solvent-exposed part of the membrane-bound α-helix such as that found in the H50Q mutant has little effect on the bilayer disrupting properties of oligomers.
authors.affiliation: †Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Anja N D
authors.initials: AN
authors.lastname: Stefanovic
authors.affiliation: †Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.|‡MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Saskia
authors.initials: S
authors.lastname: Lindhoud
authors.affiliation: †Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Slav A
authors.initials: SA
authors.lastname: Semerdzhiev
authors.affiliation: †Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.|‡MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
authors.forename: Mireille M A E
authors.initials: MM
authors.lastname: Claessens
authors.affiliation: †Nanobiophysics, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.|‡MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.|§FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
authors.forename: Vinod
authors.initials: V
authors.lastname: Subramaniam
mesh_terms: D002463:Cell Membrane Permeability; D005452:Fluoresceins / Q000737:chemistry; D006801:Humans; D008567:Membranes, Artificial; D046912:Multiprotein Complexes / Q000737:chemistry; D020125:Mutation, Missense; D010300:Parkinson Disease / Q000235:genetics; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry*; D011485:Protein Binding; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics
chemical_list: D005452:Fluoresceins; D008567:Membranes, Artificial; D046912:Multiprotein Complexes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D051844:alpha-Synuclein; C057561:1-palmitoyl-2-oleoylphosphatidylethanolamine; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine; C007740:fluorexon