Self-Organization of Actomyosin Networks Attached to Artificial Membranes

Abstract

The shape and mechanical stability of cells are highly dependent on their cytoskeleton. Actin is one of the main proteins which contributes to this biological network. The mechanical movements of the cell rely on the interaction of F-actin with several other proteins. One of these proteins is myosin II, a molecular motor protein. By hydrolysing ATP myosin is able to walk along F-actin or to induce tension on these filaments.In our model system F-actin networks are attached to pore spanning lipid bilayers (PSLBs) via electrostatical interactions or the linker protein ezrin which mimics the biological situation. Ezrin has a PIP2 binding site located at the N-terminus and a F-actin binding site at the C-terminus and is responsible for the linkage of F-actin to PIP2 present in the PSLB. Several actin binding proteins and cross-linkers are introduced during the polymerization of actin filaments.Besides the visual self-organization the mechanical properties of different F-actin networks are examined. Atomic force microscopy is used to determine the lateral membrane tension of the PSLB dependent on different actomyosin networks. The viscoelastic properties of the network will be recorded by passive microrheology using the mean square displacement of a polymer beads Brownian movement.