Repurposing Antimicrobial Protegrin-1 as a Dual-Function Amyloid Inhibitor via Cross-seeding.

ABSTRACT

Amyloids and antimicrobial peptides have traditionally been recognized as distinct families with separate biological functions and targets. However, certain amyloids and antimicrobial peptides share structural and functional characteristics that contribute to the development of neurodegenerative diseases. Specifically, the aggregation of amyloid-ß (Aß) and microbial infections are interconnected pathological factors in Alzheimer's disease (AD). In this study, we propose and demonstrate a novel repurposing strategy for an antimicrobial peptide of protegrin-1 (PG-1), which exhibits the ability to simultaneously prevent Aß aggregation and microbial infection both in vitro and in vivo. Through a comprehensive analysis using protein, cell, and worm assays, we uncover multiple functions of PG-1 against Aß, including the following (i) complete inhibition of Aß aggregation at a low molar ratio of PG-1/Aß = 0.251, (ii) disassembly of the preformed Aß fibrils into amorphous aggregates, (iii) reduction of Aß-induced cytotoxicity in SH-SY5Y cells and transgenic GMC101 nematodes, and (iv) preservation of original antimicrobial activity against P.A., E.coli., S.A., and S.E. strains in the presence of Aß. Mechanistically, the dual anti-amyloid and anti-bacterial functions of PG-1 primarily arise from its strong binding to distinct Aß seeds (KD = 1.24-1.90 µM) through conformationally similar ß-sheet associations. This work introduces a promising strategy to repurpose antimicrobial peptides as amyloid inhibitors, effectively targeting multiple pathological pathways in AD.