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.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

“…While multiple interactions and processes are likely to be involved, it does seem that membrane interactions are a key event in initiating cytotoxicity (Berthelot, Cullin & Lecomte, ; Cao & Raleigh, ; Caughey et al ., ; Couthouis et al ., ; Engel et al ., ; Harté et al ., ; Jang et al ., , ; Janson et al ., ; Kegulian et al ., ; Lee et al ., ; Lorenzo et al ., ; Matsuzaki, ; Munishkina & Fink, ; Okada et al ., ; Suwalsky, Bolognin & Zatta, ; Ta et al ., ; Valincius et al ., ), mainly by apoptosis (e.g. Bram et al ., ; Chong, Li & Maiese, ; Jang et al ., ; Liu et al ., ; Lorenzo et al ., ; Zhang et al ., ; Zhang et al ., ).…”

Probing the kinetics of lipid membrane formation and the interaction of a nontoxic and a toxic amyloid with plasmon waveguide resonance

“…The WT peptide only binds to the membrane organizing itself in the form of isolated fibers with no aggregation or membrane disruption. 15,16 Using PWR the kinetics of bilayer formation and interaction of two amyloid peptides, the non-toxic wild-type (WT) form and the toxic mutant (M8), were investigated. So far no information regarding the kinetic rates for the interaction of these or other amyloid peptides with membranes has been reported in the literature.…”

“…Additional resonances in this polarization have been observed for membranes containing mixtures of lipid ordered and disordered domains and have been attributed to microdomain formation. 9,27 Taking into account the ability of amyloid peptides to oligomerize and to form fibers and platelets, 9,16 the multiple resonances seen can correspond to different oligomeric states of the peptides. Overall the larger spectral shifts observed for both peptides in the case of DOPG indicate that electrostatic interactions with the membrane promote larger peptide accumulation; these data agree with previously reported studies from our laboratory.…”

Interaction of Aβ1–42 Amyloids with Lipids Promotes “Off-Pathway” Oligomerization and Membrane Damage

“…Therefore, it was not possible to accurately determine affinity constants. 33 Nevertheless, accumulation rate constants were determined by fitting kinetic curves (see Figure 3) and are presented in Table 2. So far no information regarding kinetic rates for the interaction of Aβ 1−42 peptide with membranes has been reported in the literature.…”