Fig. 7: Mechanical stability of an ancestral Entamoeba histolyticaα-actinin homo-dimer under shear-stretching force geometry.
a The illustration of the single-molecule construct and experimental design for quantifying the mechanical stability of the Entamoeba histolyticaα-actinin dimer. Three possible scenarios of rupture-induced bead height changes are indicated by colored dashed arrows: rupture without domain unfolding (orange), rupture with one domain unfolding (magenta) and with two domain unfolding (blue). b Representative force–bead height curves of Entamoeba histolyticaα-actinin dimer under shear-stretching force geometry during force-increase scans (5 pN s−1). Three distinct rupture behaviors were observed and plotted in top-to-bottom panels, respectively. The rupture events at each panel are noted by colored arrows. c The resulting force–step size graph of the rupture events during force-increase scans at two force-loading rates of 1 pN s−1 (red) and 5 pN s−1 (blue), respectively. The different mechanical groups are plotted with different symbols (circle, triangle, and diamond). N = 99 (red) and 56 (blue), respectively. d Top panel: inter-conversions of the three subgroups at constant forces of ~2.4 pN over 60,000 s. Second to bottom panels: the zoom-in of the time–bead height curves of the three subgroups, indicated by different colors. e The force-dependent lifetime of the Entamoeba histolyticaα-actinin dimer under shear-stretching force geometry. The dwell times of the dimer at each force were plotted in colored hollow symbols, and the characteristic lifetime of each force was plotted in solid colored symbols. Three clustered force-dependent lifetime subgroups were obtained indicated by three colored symbols, respectively. Three sets of the lifetime were fitted with Bell Model (blue, magenta and orange colored lines, respectively) to obtain the corresponding k0 and Δ. Source data are provided as a Source Data file.
