A functional artificial protein motor can be created through modular assembly of ligand-controlled DNA-binding domains that steps directionally along DNA tracks at 1.2 nm/s with 50-100 nm processivity when externally controlled by time-dependent ligand exchange, demonstrating that motor function emerges from strategic integration of non-motor protein components with nanomolar binding specificity and optimized kinetics.

Molecular motors are fundamental to life because of their ability to convert chemical energy into mechanical work, an ability that is conferred by the chemical and structural complexity of their constituent proteins. Scientists have long sought to create artificial protein motors that may reveal insights into how biological motors function. While artificial molecular motors based on small molecules and DNA have been developed, creating an artificial motor protein has remained an elusive goal in synthetic biology. Here we demonstrate the realization of an artificial protein motor called Tumbleweed (TW) that walks directionally along a DNA track under external control. TW consists of three legs, each with a ligand-gated DNA-binding domain that enables selective interaction with specific sites along a DNA track. Using single-molecule fluorescence assays and a programmable microfluidic device, we show that TW steps directionally along a designed DNA track in response to a defined sequence of ligand inputs. We built our TW molecular walker using a modular approach, combining existing proteins with known properties to achieve emergent motor function, similar to how Nature evolves new proteins. Our design strategy thus offers a a platform for engineering advanced and dynamic protein functionality. Our demonstration of TW walking represents a step toward developing fully autonomous protein motors and opens new avenues for uncovering and leveraging the principles by which biological motors transduce chemical energy into motion.