Bacterial twitching motility protein. Molecular model of a hexameric ATPase (adenosine triphosphatase) that plays a key role in pilus retraction and surface motility in bacteria. It is known as PilT, and this example is from the thermophilic bacterium Aquifex aeolicus. It is known as a twitching motility protein, and forms part of the motor complex that enables movement and retraction of the bacterium's pilus, the hair-like appendage used to exchange genetic material with other bacteria (conjugation). It is also used to enable bacterial movement (motility).