Electrostatic control of membrane disruption and amorphous coaggregation by dynorphin A variants.

Dynorphin A is a highly cationic neuropeptide that exhibits membrane activity beyond its canonical opioid receptor signaling. Here, we investigate how sequence variants of Dynorphin A associated with spinocerebellar ataxia type 23 modulate membrane disruption and aggregation behavior. Using computational electrophysiology simulations combined with liposome leakage and fluorescence-based aggregation assays, we show that Dynorphin A variants interact with lipid bilayers primarily via electrostatic recruitment, followed by mutation-dependent insertion and transient pore formation. Anionic lipids promote bilayer disruption, while cholesterol attenuates peptide activity in a variant-specific manner. Although Dynorphin A variants do not spontaneously form ordered aggregates, they markedly alter amyloid-β co-assembly by enhancing hydrophobic surface exposure without proportionally increasing fibrillization. These results demonstrate that subtle sequence changes fine-tune the balance between membrane perturbation and amorphous co-aggregation, and highlight electrostatic membrane recruitment as a key determinant of DynA bioactivity.