Intrinsically Disordered Proteins (IDP) and Aggregates: Ab, Tau, and a-Synuclein

Department of Chemistry and Biochemistry, Worcester PolytechnicInstitute, Worcester, MA, USA.NeurodegenerativediseasessuchasAlzheimer’sandParkinson’sarecharacter-ized by the presence of Lewy bodies which are plaques of aggregated proteinsfound post-mortem in brains of patients. The neurodegenerative plagues asso-ciated with Parkinson’s disease are largely composed of the protein a-synu-clein. A-Synuclein is a small cytoplasmic protein found in central nervoussystem of vertebrates. Despite intensive studies, its precise role in cells is un-known. Changes in a-synuclein oligomerization are thought to give rise tonucleation of neurodegenerative plaques. We have proposed previously thatloss of binding partners caused by environmental factors, such as oxidativestress induces a-synuclein oligomerization. Here, we investigated the effectof hydrostatic pressure on the aggregation of a-synuclein in cultured neuronalcells. We applied high hydrostatic pressure to cells in suspension for 1h andplated them in full growth medium for 24h to allow recovery and ensure thatexperiments are performed on live cells. Using western-blot and number andbrightnessanalysis of fluorescence fluctuation intensities, we found that hydro-static pressure promotes aggregation of a-synuclein in PC12 and SK-N-SHcells. We then tested whether aggregation is associated with the loss of bindingpartners, such as phospholipase Cb1. Western blot analysis indicates that hy-drostatic pressure reduces the amount of PLCb1, but not a-synuclein inneuronal cells. Using Fo¨rster resonance energy transfer between GFP-PLCb1and mCherry-a-synuclein we found that increased pressure reduces the associ-ation between PLCb1 and a-synuclein. These studies suggest that pressure in-duces cell damage that results in the loss of a-synuclein binding partners andcan promote a-synuclein aggregation.This work was supported by PSC-CUNY 45 to UG and NIH GM116178 to SS.2717-Pos Board B94Aggregation and Fibrillation of a-Synuclein by Polymorph PatchyParticlesIoana M. Ilie, Wouter K. den Otter, Wim J. Briels.Computational Biophysics, Twente University, Enschede, Netherlands.Theintricateaggregationdynamicsof alpha-synuclein, the amyloidogenic pro-tein implicated in Parkinson’s disease, is simulated with two novel highlycoarse-grainedmodels.First,theflexibleproteinismodelledasasingleparticlethatsmoothlytransformsbetweenasphericalstate,forthedisorderedproteininsolution, to a sphero-cylindrical state, for the mis-folded protein in an amyloidfibril [1]. The internal interactions favor the disordered state, while the transi-tion to the misfolded state enables stabilization by strong inter-particle interac-tions. Brownian Dynamics is used to simulate the coupled translational androtationalmotionsoftheseanisotropicparticles[2,3],aswellastheinternaldy-namics of the particles. The simulations show the formation of oligomers andfibrils from solution, inter-conversions between these aggregates, and fibril-stimulated transformation of oligomers into fibrils. Second, the protein ismodelled as a flexible chain of polymorph particles, with the variability ofthe particles representing the dynamical secondary structure of short aminoacid sequences. This model has been used to explore the free-energy profileof a protein as it folds and attaches to the end of a fibril [4].[1] I.M.Ilie, W.K. den Otter and W.J. Briels, submitted.[2]I.M.Ilie,W.J.BrielsandW.K.denOtter,J.Chem.Phys.142,114103(2015).[3]I.M.Ilie,W.K.denOtterandW.J.Briels,J.Chem.Phys.141,065101(2014).[4] I.M.Ilie, W.K. den Otter and W.J. Briels, in preparation.2718-Pos Board B95Alpha-Synuclein and its Interaction with Cytoskeleton (Associated)Proteins: Implications in Parkinson’s DiseaseSenthil Kumar Thangaraj, Lisanne Dijk, Mireille Claessens.Nanobiophysics group, University of Twente, Enschede, Netherlands.Alpha-synuclein (AS) is an intrinsically disordered protein mainly found in thepresynaptic terminals of neurons