Evaluation of Actin Curvature Dependent Actin-Arp2/3 Interaction Change Using AFM and Graphene Oxide Sheets

Actin filament senses mechanical forces and it is transduced into biochemical signals during many cellular processes. In bending of actin filaments, actin-related protein 2/3 (Arp2/3) complex plays a central role as the branching actin networks. In this study, we evaluated a quantitative analysis of the actin filament-Arp 2/3 interaction change dependent upon the actin filament curvature 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. For decreasing non-specific interactions between protein and the substrate, graphene oxide sheet was used for an interface. By single-molecule force spectroscopy, we determined rupture force of actin filament-Arp2/3 binding on the wave-like substrate and a flat substrate. The rupture force of actin filament-Arp2/3 binding at the curvature of 1.35 mu m(-1) showed a value approximately 3 times higher than the rupture force at the curvature of 0.15 mu m(-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.