Actin under stress: A Coarse Grained Approach

Actin bundles are an important structure within the cytoskeleton of the cell that give the cell structural integrity and shape while retaining flexibility. In this project Actin bundles were modeled as worm-like chains and confined into two geometries, a cylinder and torus. Worm-like chains have been shown to be a viable approach to semi-flexible polymers and these geometries effectively approximate elongation and bending. In order to get those chains to interact with each other, the Gay-berne potential was used as the interaction potential between the worm-like chains. A metropolis-monte carlo simulation was then used in order to generate these chains in confined spaces. Two confinement geometries were used, a cylinder and a torus. The cylinder was used to simulate the worm-like chains in an elongated state, and the torus was used to simulate the worm-like chains in a bent state. In experimental studies of Actin bundles, these two states were used in order to study Actin bundle reorganization. The findings of this project suggests that simulating bundles of interacting worm-like chains in different geometries does in fact change the bundling structure. While this is an exciting result, more data and analysis is needed in order to conclude if this a viable model to approximate Actin bundles or not.