Creating Protein-Based Molecular Motors That Move along DNA Nanotubes

Abstract

Linear molecular motors such as myosin, kinesin, and dynein are enzymes that move toward one end of cytoskeletal filaments. These motors are unusual nanomachines because they can robustly move unidirectionally even in the storm of thermal agitation. Despite the decades of studies, however, the essential mechanisms of directional motion remain unclear. For example, we do not understand how the structural change of motors, and the asymmetric structures of the motor-filament interface contribute to directional motion. A limitation is that neither motors nor cytoskeletal filaments can be rationally re-designed, making it difficult to address these key questions. To overcome this limitation, we took bottom-up approaches where new molecular motors and tracks are designed and created based on protein and DNA building blocks. Through the process of creation, we will understand the essential factors for a molecular motor to move forward. Here we constructed a new hybrid motor from dynein and a DNA-binding protein. We chose DNA as a track instead of cytoskeletal filaments because DNA have a lot of advantages: it is stable, synthesizable, and can be self-organized into higher order structures. In in vitro motility assays, the new hybrid motors successfully translocated 10-helix DNA nanotubes at an average velocity of 8 nm s−1. Furthermore, the multiple molecules of hybrid motors transported single DNA origami cargoes along immobilized DNA nanotubes. Control experiments showed that the hybrid motors recognize the specific DNA sequence that is periodically incorporated along the long axis of the DNA nanotube. Our strategy opens the way to systematic studies on the mechanisms of motors, and to nanotechnological applications using the powerful DNA-based molecular toolbox.