Living cells run on molecular motors, proteins that haul cargo, copy DNA and contract muscle. Building such a motor from scratch has been a long-standing ambition of synthetic biology, and a team led by Heiner Linke, professor of nanophysics at Lund University's Faculty of Engineering, has now achieved a milestone: an artificial protein motor, named Tumbleweed, that moves in controlled, directed steps along a DNA track.
Tumbleweed has three feet, each of which binds a specific DNA sequence. By changing the surrounding chemical environment, the researchers determine which feet can attach at any moment, clocking the motor through alternating steps and steering its direction. The work, carried out with the University of New South Wales alongside partners in Bayreuth, Simon Fraser and Bristol, shows that moving machines can be engineered from the same class of building blocks that biology itself uses, rather than from simpler synthetic molecules or DNA alone.
Most recent triumphs of protein design, including work recognised by the 2024 Nobel Prize in Chemistry, have produced static structures. Tumbleweed is dynamic and externally controllable, which the researchers liken to a first step on a longer road: the eventual goal is a protein walker that moves autonomously, powered by chemical fuel. Proteins are harder to engineer than DNA, but they offer far more scope for refinement, suggesting a route towards practical nanomachines for assembly and transport at the molecular scale.