Aβ-AMYLOID FIBRILS ARE SELF-TRIGGERED BY THE INTERFACIAL LIPID ENVIRONMENT AND LOW PEPTIDE CONTENT

PABLO RODRIGUEZ; ALAIN BOLAÑO; GERARDO D FIDELIO; BENJAMÍN CARUSO; STEFFEN B PETERSEN

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2020 vol. 36 p. 8056 - 8065

0743-7463

We studied the surface properties of Aβ(1-40) amyloid peptide mixed with POPC (liquid state) orDSPC (solid state) phospholipids by using nano-structured lipid/peptide films (Langmuir monolayers). PureAβ(1-40) amyloid peptide forms insoluble monolayers without forming fibril-like structures. In a lipidenvironment (phospholipid/Aβ(1-40) peptide mixtures), we observed that both miscibility and stability ofthe films depend on peptide content. At low Aβ(1-40) amyloid peptide proportion (from 2.5 % to 10 % ofpeptide area proportion) we observed the formation of fibril-like structure when mixed only with POPClipid. The stability acquired by these mixed films is within 20-35 mN.m-1 compatible with the equivalentsurface pressure postulated for natural biomembranes. Fibrils are clearly evidenced directly from themonolayers by using Brewster Angle Microscopy. The so-called nano-structured fibrils are Thioflavin Tpositive when observed with fluorescence microscopy. The amyloid fibril network at the surface was alsoevidenced by Atomic Force Microscopy when the films are transferred onto mica support. Aβ(1-40) amyloid mixed with the solid DSPC lipid showed an immiscible behavior in all peptide proportionswithout fibrils formation. We postulated that the amyloid fibrillogenesis at the membrane can be dynamicallynano-self-triggered at the surface by the quality of the interfacial environment, i.e. the physical state of thewater-lipid interface and the relative content of amyloid protein present at the interface.