Zinc Differentially Modulates Tau Aggregation, Fibril Morphology, and Prion-like Seeding in a Construct-Dependent Manner

The role of tau fibril structure in seeding and propagation of aggregation remains a central unresolved question in tauopathy biology. While non-proteinaceous cofactors are increasingly observed in patient-derived tau filaments, whether they actively determine fibril structure and function is not well understood. Here, we show that zinc, a divalent cation dysregulated in Alzheimers disease (AD), can drive fundamentally different aggregation and seeding outcomes depending on tau sequence context. Using heparin-free conditions, we compared full-length 2N4R tau (residues 1-441) with an AD-tau fragment (residues 304-380) corresponding to the ordered fibril core. Strikingly, Zn2+ exerted opposite