Fig. 1: Schematics of DNA catch bond design and expected behaviour.
a Schematic of a two-state mechanism that allows the DNA construct to dissociate via two pathways directed by force above or below a crossover force (Fc). In the weak pathway, the closed jaw locks the hook in the unzipping geometry. In the strong pathway, the open jaw switches the hook to the shearing geometry. b The lifetimes (Ï„F) of the hook unzipping and jaw opening are designed to intersect, enabling force-dependent pathway selection. c Below Fc, the construct follows the weak pathway, as the jaw remains closed, and thus the hook unzips. Above Fc, the jaw opens before the hook, steering the construct into the strong pathway, thereby increasing the proportion of constructs with an open jaw (Pjaw-open) as force escalates. d As the force increases, the transition from the hook unzipping to shearing creates a slip-catch-slip behaviour. e Slip bonds are characterized by a unimodal rupture force probability density function (PDF) at a specific loading rate. f In contrast, catch bonds exhibit a bimodal rupture force PDF (catch-slip-catch shown here). Here, the high rupture force population (red) corresponds to high-force slip behaviour and the low rupture force population (green) arises from the catch behaviour. For comparison, a slip-only PDF is represented by a grey dashed line. The catch behaviour shifts subpopulations from high-force to low-force ruptures (grey arrows). g Additionally, the fraction of high rupture force in the bimodal distribution increases with force ramp speed or loading rate.
