There are many known molecular motors in nature that are crucial for various cellular processes1,2. Much progress has been made to characterise the structural details of various biological motors, allowing models to be proposed to describe their function3,4. However, the fundamental properties and detailed mechanisms required for motor proteins to carry out complex biological functions is still not well understood. It has been hypothesised that properties such as processivity, the use of thermal motion and the ability to transfer information between distant sites are important for the function of motor proteins5.
The research focus of our group is to understand how biological molecular motors and machines function in nature. To achieve this, we hope to design and build the world’s first functional, artificial protein motor from the bottom up, which would enable us to test the properties hypothesised to be important for motor performance.
We have synthesised a three-legged protein motor called Tumbleweed (TW), designed to walk along a DNA track in a ligand-gated fashion. TW is assembled using different protein components that have known atomic structures. Verifying if Tumbleweed is assembled correctly using SAXS is an important first step before we can begin testing if the motor protein can function by walking along DNA. SAXS data suggests that the protein is an elongated and branched structure with a maximum length of ~300Å. AFM in solution is being used to further probe the structure of TW and to characterise binding of the protein to various DNA tracks. It is hoped that AFM studies of TW alone and in complex with DNA tracks will inform us of suitable conditions towards characterisation by cryo-TEM.
Visualisation of TW protein in complex with DNA tracks at a molecular level will complement biophysical studies aimed at characterising the function of this artificial motor protein.