Extended Data Fig. 6: Helicity propagation in H46 MD trajectories.
From: The structure of pathogenic huntingtin exon 1 defines the bases of its aggregation propensity
(a) Plot showing the number of times (in log scale) an α-helix expands 1 to 5 residues towards the C-terminus (+1 to +5) or the N-terminus (-1 to -5) from each of the residues of N17 and poly-Q. For all the positions (1 to 5), the number of events is greater in direction of the C-terminus than the N-terminus, indicating a higher propensity of helix propagation from N- to C-terminus. The comparison of the number of events for expansion of a helix by 1, 2 and 3 residues towards the N- or C-terminus is presented in (b) for further clarity. These plots show that in httex1 helical segments are more prone to expand towards the C-terminus than towards the N-terminus. Additionally, the preference for directional growing increases with the extent of propagation, that is, the relative difference in the number of events where a helix is propagated three residues towards the C-terminus and the N-terminus is larger than propagation the of two residues, which is in turn larger than the propagation of a single residue.
