Acceleration of amyloid fibril formation by specific binding of Aβ-(1- 40) peptide to ganglioside-containing membrane vesicles

Abstract

The interaction of Alzheimer's Aβ peptide and its fluorescent analogue with membrane vesicles was studied by spectrofluorometry, Congo Red binding, and electron microscopy. The peptide binds selectively to the membranes containing gangliosides with a binding affinity ranging from 10-6 to 10-7 M depending on the type of ganglioside sugar moiety. This interaction appears to be ganglioside-specific as under our experimental conditions (neutral pH, physiologically relevant ionic strength), no Aβ binding was observed to ganglioside-free membranes containing zwitterionic or acidic phospholipids. Importantly, the addition of ganglioside-containing vesicles to the peptide solution dramatically accelerates the rate of fibril formation as compared with that of the peptide alone. The present results strongly suggest that the membrane-bound form of the peptide may act as a specific 'template' (seed) that catalyzes the fibrillogenesis process in vivo.