Mechanism of cardiac tropomyosin transitions on filamentous actin as revealed by all-atom steered molecular dynamics simulations

MR Williams, JC Tardiff… - The journal of physical …, 2018 - ACS Publications
MR Williams, JC Tardiff, SD Schwartz
The journal of physical chemistry letters, 2018ACS Publications
The three-state model of tropomyosin (Tm) positioning along filamentous actin allows for Tm
to act as a gate for myosin head binding with actin. The blocked state of Tm prevents myosin
binding, while the open state allows for strong binding. Intermediate to this transition is the
closed state. The details of the transition from the blocked to the closed state and then finally
to the open state by Tm have not been fully accessible to experiment. Utilizing steered
molecular dynamics, we investigate the work required to move the Tm strand through the …
The three-state model of tropomyosin (Tm) positioning along filamentous actin allows for Tm to act as a gate for myosin head binding with actin. The blocked state of Tm prevents myosin binding, while the open state allows for strong binding. Intermediate to this transition is the closed state. The details of the transition from the blocked to the closed state and then finally to the open state by Tm have not been fully accessible to experiment. Utilizing steered molecular dynamics, we investigate the work required to move the Tm strand through the extant set of proposed transitions. We find that an azimuthal motion around the actin filament by Tm is most probable in spite of increased initial energy barrier from the topographical landscape of actin.
ACS Publications