Detection of Actin Filament and Cofilin Interaction Change by Actin Filament Curvature Decreasing

Actin filament senses mechanical forces and it is transduced into biochemical signals during many cellular processes. In the disassembling process of actin filaments, cofilin plays a central role as the actin filament depolymerization. In this study, we evaluated a quantitative analysis of the actin filament-cofilin interaction change dependent upon the actin filament curvature decrease using atomic force microscopy (AFM) and a fabricated wave-like substrate. A wave-like substrate was fabricated by a maskless photo-lithography of a spin coated film on a glass substrate, and graphene oxide sheet was used for the decreasing of non-specific interaction between protein and the substrate. By single-molecule force spectroscopy, we determined rupture force of actin filament-cofilin binding on the wave-like substrate and a flat substrate. The rupture force of actin filament-cofilin binding at the curvature of -1.35 μm-1 showed a value approximately 4 times higher than the rupture force at the curvature of -0.15 μm-1. The present study will provide the possibility and quantitative evidence that mechanical stress on cytoskeletal filaments can modulate how they interact with their binding proteins.