Dynamics of ATP-dependent and ATP-independent steppings of myosin-V on actin: catch-bond characteristics

Figures

• 

  Figure 1.. Model of chemomechanical coupling of myosin-V at low ATP. (a–l) Schematic illustrations of the chemomechanical coupling pathway (see text for detailed description). The thickness of each arrow represents the magnitude of the transition rate or probability under no load. Inside box: (a′–c′) orientations of the neck domain relative to motor domain bound to actin filament in different nucleotide states; (d′) the relative orientation of the two heads in the equilibrium state with one head bound to actin and the other head detached from the actin, with the right panel corresponding to the side view of the left panel. Stars represent the position of the gold particle labelled to the head used in the experiments of Andrecka et al. [31].

• 

  Figure 2.. Model of chemomechanical coupling and unbinding of myosin-V at saturating ATP. (a–g) Schematic illustrations of the occurrence of the weak affinity state with myosin-V binding weakly to actin (see text for detailed descriptions). The thickness of each arrow represents the magnitude of the transition probability under no load.

• 

  Figure 3.. Results for dynamics of chick brain myosin-V under experimental conditions of Uemura et al. [6]. Lines are theoretical data with consideration of only ATP-dependent stepping. Symbols are experimental data from Uemura et al. [6,49]. (a) Force dependence of inverse of stepping ratio at saturating ATP (1 mM). (b) Force dependence of velocity at low and saturating ATP concentrations. (c) Force dependence of mean dwell time at low and saturating ATP concentrations.

• 

  Figure 4.. Results for dynamics of chick brain myosin-V under experimental conditions of Gebhardt et al. [9]. Lines are theoretical data with consideration of both ATP-dependent and ATP-independent steppings. Symbols are experimental data from Gebhardt et al. [9]. (a) Velocity versus force at 1 µM ATP. (b) Velocity versus ATP concentration at –5 pN (forward) and 5 pN (backward) forces. (c) Velocity versus ATP concentration at –10 pN (forward) and 10 pN (backward) forces.

• 

  Figure 5.. Results for dynamics of murine myosin-V at no load under experimental conditions of Zhang et al. [7]. Lines are theoretical data with consideration of only ATP-dependent stepping, with red dashed lines corresponding to the case that the unbinding of the motor can occur only during Period W and black solid lines corresponding to the case that the unbinding can occur during both Period W and other periods. Symbols are experimental data from Zhang et al. [7], with the experimental data in (c) being calculated from those in (a) and (b). (a) Velocity versus ATP concentration. (b) Run length versus ATP concentration. (c) Unbinding rate versus ATP concentration.

• 

  Figure 6.. Results for dynamics of chick brain myosin-V at saturating ATP under experimental conditions of Clemen et al. [8]. Lines are theoretical data with consideration of only ATP-dependent stepping, with red dashed lines corresponding to the case that the unbinding of the motor can occur only during Period W and black solid lines corresponding to the case that the unbinding can occur during both Period W and other periods. Symbols are experimental data from Clemen et al. [8], with the experimental data in (c) being calculated from those in (a) and (b). (a) Force dependence of velocity. (b) Force dependence of run length. (c) Force dependence of unbinding rate.

• 

  Figure 7.. Results for dynamics of chick brain myosin-V under experimental conditions of Gebhardt et al. [9]. Lines are predicted theoretical data at different ATP concentrations with consideration of both ATP-dependent and ATP-independent stepping. (a) Force dependence of velocity. (b) Force dependence of run length. (c) Force dependence of unbinding rate.

• 

  Figure 8.. Results for dynamics of chick brain myosin-V at saturating ATP under experimental conditions of Clemen et al. [8]. Line are theoretical data, with black solid lines corresponding to the case with consideration of both ATP-dependent and ATP-independent steppings, while the red dashed line corresponding to the case with consideration of only ATP-dependent stepping. Symbols are experimental data from Clemen et al. [8]. (a) Force dependence of run length. (c) Force dependence of unbinding rate.

• 

  Figure 9.. Results for biphasic character of dwell-time distribution for backward steps under superstall force (F > 3 pN) under experimental conditions of Gebhardt et al. [9]. Lines are theoretical data. Symbols are experimental data from Gebhardt et al. [9]. (a) Force dependences of rate constants λ1 and λ2. (b) Force dependence of amplitude ratio Z2/Z1.