Fig. 2: Modulating the mechanical stability of helix-bundles.
From: Modulating mechanical stability of heterodimerization between engineered orthogonal helical domains
a Top panel: design of the 13-a2a1Lb1b2 construct. Bottom panel: The expected structure of the 13-abshear. b Four representative force–height curves of the 13-a2a1Lb1b2 construct obtained at 1.0 ± 0.1 pN s−1. The stepwise bead height jump indicates the force-induced rupturing (unlooping) of the 13-abshear. c The force–step size graph of the force-dependent rupture transitions of the 13-abshear that causes unlooping of the construct. The dash curves are theoretically predicted. d Normalized histograms of the 13-abshear rupture forces. e Force-dependent lifetimes of the 13-abshear. f Top panel: design of the 13-a2Lb1b2 construct. Bottom panel: the expected structure of the 13-ahalfb. g Four representative force–height curves of the single-molecule 13-a2Lb1b2 construct at 1.0 ± 0.1 pN s−1. The stepwise bead height jump indicates the force-induced rupturing (unlooping) of the 13-ahalfb. The force–step size graph of the force-dependent rupturing (unlooping) transitions of the 13-ahalfb. The dash curves are theoretically predicted. i Normalized histograms of the 13-ahalfb helix-heterotrimer rupture forces. j Force-dependent lifetimes of the 13-ahalfb helix-heterotrimer. For panels b–e and g–j: the experiments were performed at 23 °C. For panels c, d, h, and i, the number of data points obtained from >5 independent tethers are indicated. Force panels e and j, the solid squares represent the average lifetimes (τ) obtained by best-fitting of the lifetime histogram to a single-exponential decay function. The hollow gray circles represent individual lifetimes (N ~ 100 for each force) measured in experiments. The vertical error bars indicate the standard errors of the lifetime obtained by \(\frac{\tau }{{\sqrt {N - 1} }}\). The horizontal error bars indicate 10% of relative force uncertainty resulted from the force-calibration method. For panels b and g 20-points FFT smooth (colored lines) of the raw data (gray lines) are shown. Source data are provided as a Source Data file.
