Figure 4.

Unfolding pathway of DrBphP CBD. (A) Zoom into single holo-CBD unfolding event (framed in Fig. 3A). Rising force connects to a stable intermediate state, with WLC fit shown as green line. (B) Histogram of contour-length increases from totally folded to intermediate state $\Delta L_I^{Holo}$. (C) Histogram of forces needed to unfold first part of structure (A, red circles). Average unfolding forces are $F_{18,314}^{Holo}$ = 73.3 ± 6.6 pN. (D) Histogram of forces $F_I^{Holo}$ needed to unfold intermediate state to fully extended protein (A, gray circles). The average unfolding forces are $F_I^{Holo}$ = 32.8 ± 4 pN. (E) Zoom into a single apo-CBD unfolding event (framed in Fig. 3C). $\Delta L_I^{Apo}$ as fit by WLC is shown as green line. (F) Histogram of $\Delta L_I^{Apo}$. (G) Histogram of forces needed to unfold first part of structure (E, red circles). Average unfolding force is $F_{18,314}^{Apo}$ = 47.1 ± 3.2 pN. (H) Histogram of forces needed to unfold intermediate state (E, gray circles), with average value of $F_I^{Apo}$ = 27.7 ± 2.8 pN.