The double-layered structure of amyloid-β assemblage on GM1-containing membranes catalytically promotes fibrillization

Alzheimer’s disease (AD) is associated with progressive accumulation of amyloid-β (Aβ) cross-β fibrils in the brain. Aβ species tightly associated with GM1 ganglioside, a glycosphingolipid abundant in neuronal membranes, promote amyloid fibril formation; therefore, they could be attractive clinical targets. However, the active conformational state of Aβ in GM1-containing lipid membranes is still unknown. The present solid-state nuclear magnetic resonance study revealed a nonfibrillar Aβ assemblage characterized by a double-layered antiparallel β-structure specifically formed on GM1 ganglioside clusters. Our data show that this unique assemblage was not transformed into fibrils on GM1-containing membranes, but could promote conversion of monomeric Aβ into fibrils, suggesting that a solvent-exposed hydrophobic layer provides a catalytic surface evoking Aβ fibril formation. Our findings will offer structural clues for designing drugs targeting catalytically active Aβ conformational species for the development of anti-AD therapeutics.