Non-muscle myosin II, essential for cytokinesis, cell migration, and cytoskeletal organization, forms dimers with coiled-coil tails. Human non-muscle myosin II leads to robust bipolar filaments mediated through periodic charge distribution patterns. However, current evidence suggests that fission yeast Myo2 assembles into the cytokinetic nodes for the contractile ring in a bouquet arrangement with weak or no filament bundle formation. To better understand the mechanisms underlying non-muscle myosin II organization, we used coarse-grained simulations that account for electrostatic interactions at a resolution of one bead per aminoacid. We constructed straight coiled coils by concatenating short tail segments of Alphafold3 predictions that otherwise predicts self-folding of whole tails. We use an elastic network model to allow for tail flexibility. OpenMM and the OpenABC framework was used to investigate the interaction between myosin II dimers aligned in parallel and antiparallel orientations and varying degree of overlap. To sample the binding landscape, we implemented adaptive external pulling sliding forces, dynamically scaled based on center-of-mass separation velocities. This allows overcoming barriers while maintaining quasi-equilibrium sampling during simulated tail sliding. Our results confirm stable overlapping lengths reported in prior human non-muscle myosin II studies, with electrostatic forces playing a pivotal role in stabilizing tail interactions. Ongoing work investigates Myo2 tails.
Geng et al. (Sun,) studied this question.