Solutions of burnt-bridge models for molecular motor transport

Transport of molecular motors, stimulated by interactions with specific links between consecutive binding sites (called "bridgesa"), is investigated theoretically by analyzing discrete-state stochastic "burnt-bridgea" models. When an unbiased diffusing particle crosses the bridge, the link can be destroyed ("burneda") with a probability p, creating a biased directed motion for the particle. It is shown that for probability of burning p=1 the system can be mapped into a one-dimensional single-particle hopping model along the periodic infinite lattice that allows one to calculate exactly all dynamic properties. For the general case of p<1 a theoretical method is developed and dynamic properties are computed explicitly. Discrete-time and continuous-time dynamics for periodic distribution of bridges and different burning dynamics are analyzed and compared. Analytical predictions are supported by extensive Monte Carlo computer simulations. Theoretical results are applied for analysis of the experiments on collagenase motor proteins.