Kinetics of filament bundling with attractive interactions.
We study the kinetics of filament bundling by variable time-step Brownian-dynamics simulations employing a simplified attractive potential based on earlier atomic-level calculations for actin filaments. Our results show that collisions often cluster in time, due to memory in the random walk. The clustering increases the bundling opportunities. Small-angle collisions and collisions with short center-to-center distance are more likely to lead to bundling. Increasing the monomer-monomer attraction decreases the bundling time to a diffusional limit, which is determined by the capture cross-section and diffusion coefficients. The simulations clearly show that the bundling process consists of two sequential phases: rotation, by which two filaments align parallel to each other; and sliding, by which they maximize their contact length. Whether two filaments bundle or not is determined by the competition between rotation to a parallel state and escape. Increasing the rotational diffusion coefficient and attraction enhances rotation; decreasing attraction and increasing the translational diffusion coefficients enhance escape. Because of several competing effects, the filament length only affects the bundling time weakly.
Yu
Xueping
X
Physics Department, Washington University, St. Louis, Missouri, 63130, USA. xyu@artsci.wustl.edu
Carlsson
A E
AE
D008841:Actin Cytoskeleton / Q000737:chemistry*; D001665:Binding Sites; D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D004058:Diffusion; D019281:Dimerization; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000032:analysis / Q000737:chemistry; D011485:Protein Binding; D011487:Protein Conformation; D055672:Static Electricity
D046912:Multiprotein Complexes