Mini-Motor Models Nature, Advances Miniaturization Technology

Natural molecular motors enable bacteria and protozoa to speed through their environments and, in humans, are essential for processes that range from muscle contraction and intracellular transport to oviduct functioning and sperm swimming.

The prototype molecular motor was designed and constructed by Dr. T. Ross Kelly and coworkers at Boston College. A report describing the motor appears in the September 9 issue of Nature.

"This is significant from two points of view," said Dr. John Schwab, a program director at the National Institute of General Medical Sciences (NIGMS), which supported the work. "One is that it proves we understand, at least in some sense, how nature might convert chemical energy into controlled motion."

Such knowledge may help scientists understand the molecular motors in muscles and the thread-like hairs called cilia inside lungs and other organs. It may also have future applications in understanding diseases in which molecular motors are faulty, such as some cases of infertility, some respiratory and digestive disorders, and an inherited brain disease.

The work is also an extraordinary example of miniaturization of technology, said Dr. Schwab. "This is going orders of magnitude beyond nanotechnology, which we can visualize using optical microscopy or electron microscopy. We're taking it all the way to the single molecule level, which is quite exciting."

Dr. Kelly's motor is a small organic molecule containing less than 50 carbon atoms. It operates as a unidirectional ratchet and is powered by a chemical called carbonyl dichloride. In contrast, nature's molecular motors are larger protein molecules fueled by the universal unit of cellular energy called adenosine triphosphate (ATP). Dr. Kelly's device mimics the ability of molecular motors to convert chemical energy into ATP and therefore may help researchers understand the natural process at an atomic-level. Dr. Kelly and his group are now modifying their motor to operate faster and to run continuously.

In addition to advancing the scientific understanding of molecular motors, Dr. Kelly sees the work as a continuation of historical efforts at miniaturization. He explains this in a manuscript:

"The development of motors of ever diminishing size has riveted the attention of inventors since the achievement of steam engines by Newcomen and Watt upwards of two centuries ago. Nobel laureate physicist Richard Feynman once posted a $1,000 prize for constructing an operating electric motor only 1/64 inch cube. The award was collected within the year."

The quest for an atomic-level understanding of molecular motors has been described as the most extensive research effort in biophysics in the last forty years. Dr. Kelly provides the first simple model to advance this understanding.