Biophysical Properties of Intrinsically Disordered p130Cas Substrate Domain — Implication in Mechanosensing
Figure 2
AFM stretching of individual CasSD–I27–CasSD–I27 molecules in a constant-velocity mode.
(A) Scheme of the CasSD–I27–CasSD–I27 protein construct used in the current study where it is stretched from the two termini. (B) Typical force vs. extension trajectories obtained. Only the curves showing signatures of two I27 unfolding peaks (ΔL = 28±2 nm, F>100 pN, labeled +) are recorded (73 traces), and any other feature (labeled *) not associated with I27 is assigned to CasSD domains. Curve i (type-1), a typical trajectory with only two force peaks for I27, indicating that this CasSD has a floppy structure with almost no resistance to AFM pulling (below the detection limit 15 pN); Curve ii to iv (type-2), typical trajectories with some features for CasSD. Type-1 curves (42 traces) dominate. (C) A plot of unfolding peak forces vs. contour length changes ΔL from type-2 curves as shown in (A) (I27 excluded), showing points distributed without correlation between peak forces and ΔL for all unfolding events. Top and right side panels of (C) show broadly and randomly distributed histograms of peak force and ΔL respectively.