Fig. 6

Human, mouse, and chimeric aSyn variants form amyloid-like fibrils with similar dimensions but different morphologies. (A-D) Results of AFM analysis of fibrils prepared from recombinant h-aSyn A53T (a), m-aSyn (b), h-aSyn Chimera (c), and m-aSyn Chimera (d). Panels A(i) – D(i) on the left show typical AFM topographic images of fibrils formed by each aSyn variant. Dashed boxes indicate areas shown at a higher magnification in a spectral color scheme in panels A(ii) – D(ii). Panels A(iii)-D(iii) on the right show cross-section profiles. Regions of the fibrils from which the profiles are taken are shown with white solid lines on the AFM images in panels A(ii)-D(ii). Twisted fibrils were observed for m-aSyn (B) and h-aSyn Chimera (C). Twisted and non-twisted fibrils account for 65 and 35% (respectively) of total fibrils formed by m-aSyn, and 76 and 24% (respectively) of total fibrils formed by h-aSyn Chimera. Cross-section profiles in panels A(iii) and D(iii) reveal heights of non-twisted fibrils (~ 8–11 nm). Cross-section profiles 1 and 2 reveal heights of twisted fibrils at valley regions (~ 7–9 nm) and peak regions (~ 11–12 nm), respectively, in panels B(iii) and C(iii). (E, F) Histograms showing distances between peaks of twisted fibrils formed by m-aSyn (e) and h-aSyn Chimera (f). The distances were determined from cross-section profiles obtained along the long axis of the fibrils. (G-L) Representative TEM images of fibrils formed by h-aSyn WT (g), h-aSyn A53T (h), m-aSyn (i), h-aSyn Chimera (j), and m-aSyn Chimera (k). Scale bar, 100 nm. (l) Higher-magnification images generated from boxed regions of panels G, I, and J show a pair of fibrils wound around each other via a helical twist (I), two fibrils aligned in parallel (II), or individual fibrils with a twisted morphology (III and IV)