ABSTRACT
Forces and stresses generated by the action of myosin minifilaments are analyzed in idealized computer-generated actin bundles, and compared to results for isotropic actin networks. The bundles are generated as random collections of actin filaments in two dimensions with constrained orientations, crosslinked and attached to two fixed walls. Myosin minifilaments are placed on actin filament pairs and allowed to move and deform the network so that it exerts forces on the walls. The vast majority of simulation runs end with contractile minifilament stress, because minifilaments rotate into energetically stable contractile configurations. This process is aided by the bending and stretching of actin filaments, which accomodate minifilament rotation. Stresses for bundles are greater than those for isotropic networks, and antiparallel filaments generate more tension than parallel filaments. The forces transmitted by the actin network to the walls of the simulation cell often exceed the tension in the minifilament itself.
Subject(s)
Actin Cytoskeleton/metabolism , Actins/metabolism , Myosins/metabolism , Computer Simulation , Models, Biological , Stress, Mechanical , ThermodynamicsABSTRACT
Stress generation by myosin minifilaments is analyzed via simulation of their motion in a random actin network. The stresses are overwhelmingly contractile because minifilament equilibrium positions having contractile stress have lower energy than those for expansive stress. Force chains lead to unexpectedly large stresses.
