title: A yeast toxic mutant of HET-s amyloid disrupts membrane integrity.
abstract: Many studies have pointed out the interaction between amyloids and membranes, and their potential involvement in amyloid toxicity. Previously, we generated a yeast toxic amyloid mutant (M8) from the harmless amyloid protein by changing a few residues of the Prion Forming Domain of HET-s (PFD HET-s(218-289)) and clearly demonstrated the complete different behaviors of the non-toxic Wild Type (WT) and toxic amyloid (called M8) in terms of fiber morphology, aggregation kinetics and secondary structure. In this study, we compared the interaction of both proteins (WT and M8) with membrane models, as liposomes or supported bilayers. We first demonstrated that the toxic protein (M8) induces a significant leakage of liposomes formed with negatively charged lipids and promotes the formation of microdomains inside the lipid bilayer (as potential "amyloid raft"), whereas the non-toxic amyloid (WT) only binds to the membrane without further perturbations. The secondary structure of both amyloids interacting with membrane is preserved, but the anti-symmetric PO(2)(-) vibration is strongly shifted in the presence of M8. Secondly, we established that the presence of membrane models catalyzes the amyloidogenesis of both proteins. Cryo-TEM (cryo-transmission electron microscopy) images show the formation of long HET-s fibers attached to liposomes, whereas a large aggregation of the toxic M8 seems to promote a membrane disruption. This study allows us to conclude that the toxicity of the M8 mutant could be due to its high propensity to interact and disrupt lipid membranes.
authors.affiliation: Université Bordeaux 1, Allée Geoffroy de Saint Hilaire, Pessac, France.
authors.forename: Ha Phuong
authors.initials: HP
authors.lastname: Ta
authors.forename: Karine
authors.initials: K
authors.lastname: Berthelot
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Coulary-Salin
authors.forename: Sabine
authors.initials: S
authors.lastname: Castano
authors.forename: Bernard
authors.initials: B
authors.lastname: Desbat
authors.forename: Pierre
authors.initials: P
authors.lastname: Bonnafous
authors.forename: Olivier
authors.initials: O
authors.lastname: Lambert
authors.forename: Isabel
authors.initials: I
authors.lastname: Alves
authors.forename: Christophe
authors.initials: C
authors.lastname: Cullin
authors.forename: Sophie
authors.initials: S
authors.lastname: Lecomte
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000682:Amyloid / Q000737:chemistry* / Q000235:genetics; D002462:Cell Membrane / Q000737:chemistry*; D020285:Cryoelectron Microscopy / Q000379:methods; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D007700:Kinetics; D037102:Lectins / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D021962:Membrane Microdomains / Q000737:chemistry; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008969:Molecular Sequence Data; D009154:Mutation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D000596:Amino Acids; D000682:Amyloid; D005656:Fungal Proteins; C083891:HET-S protein, Podospora anserina; D037102:Lectins; D008051:Lipid Bilayers; D008055:Lipids; D008081:Liposomes