Understanding Periperal Membrane Protein Interactions | BPS Thematic Meeting

Understanding Peripheral Membrane Protein Interactions: Structure, Dynamics, Function and Therapy

Poster Abstracts

5-POS Board 5 TARGETING THE ALPHA-SYNUCLEIN NAC DOMAIN: MECHANISTIC INSIGHTS INTO AGGREGATION AND THERAPEUTIC INHIBITION Viswanath Das 1,2 ; Maryam Nikkhah 3 ; Suncica Sukur 1 ; Faramarz Mehrnejad 4 ; Marián Hajdúch 1,2 ; Saman Hosseinkhani 5 ; 1 Palacký University and University Hospital Olomouc, Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Olomouc, Czech Republic 2 Palacký University Olomouc, Institute of Molecular and Translational Medicine, Czech Advanced Technologies and Research Institute, Olomouc, Czech Republic 3 Tarbiat Modares University, Department of Nanobiotechnology, Faculty of Biological Sciences, Tehran, Iran 4 University of Tehran, Department of Nanobiotechnology and Biomimetics, School of Life Science Engineering, Tehran, Iran 5 Tarbiat Modares University, Department of Biochemistry, Faculty of Biological Sciences, Tehran, Iran α -Synuclein ( α Syn) is an intrinsically disordered peripheral membrane protein implicated in Parkinson’s disease. The non-amyloid component (NAC) domain (residues 61–95) drives fibrillization, yet the sequence determinants of nucleation and fibril stability remain incompletely defined. We dissected the NAC domain into truncated peptides to resolve the minimal sequence required for nucleation. Aggregation kinetics, electron microscopy, and a cell-based CFP/YFP FRET biosensor assay revealed that the hydrophobic GAVV motif (residues 68–71) is essential for initiating aggregation: peptides lacking this motif failed to form fibrils, whereas NAC35 (61– 95), NAC16 (63–78), and NAC11 (68–78) aggregated efficiently. Only NAC35, which includes C-terminal residues 79–95, produced stable fibrils competent to seed α Syn aggregation, indicating a separation of function between nucleation (68–71) and stabilization/seeding (79– 95).We designed poly-arginine–tagged peptide inhibitors centered on the KISVRV core and evaluated their effects on aggregation, fibril morphology, and seeding. The PB inhibitor strongly reduced α Syn fibril formation, altered fibril architecture, and decreased intracellular seeding activity. Molecular dynamics simulations (1 µs) revealed preferential PB binding to residues A69–A78, disruption of intermolecular NAC–NAC hydrogen bonding, increased solvent exposure (SASA), and prevention of compact fibril-like clustering. These results identify discrete hydrophobic determinants within the NAC domain that govern α Syn nucleation and show that targeted disruption impairs both aggregation and prion-like propagation. This work was supported by GACR (23-06301J), EXCELES (LX22NPO5107, LX22NPO5102), TN02000109, CZ-OPENSCREEN (LM2023052), EATRIS-CZ (LM2023053), BBMRI (LM2023033), Czech-BioImaging (LM2023050; LM2018129), and VIDEC (872195).

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