Discovery of reversible motor protein could shed light on cancer growth

Click on image to see motion: The motor protein KLpA moves in one direction and switches to the opposite direction between a pair of microtubules. Illustration credit: KuoFu Tsung, Oregon State University

It’s amazing enough that the “motor” proteins in our cells move along little train-track like structures called microtubules, carry cargos, and build and maintain the mitotic spindle, the football-shaped macromolecular structures that animal and fungi cells depend on to ensure accurate chromosome segregation during cell division.

But now, according to a recent discovery by physicist Weihong Qiu, at least one motor protein is capable of reversing direction!

Qiu’s Single-Molecule Biophysics Laboratory recently published a study in Nature Communications reporting on this unexpected mechanical property of a particular motor protein called KlpA. Using a high-sensitivity microscopy method to directly visualize the motion of individual KlpA molecules on microtubules,the Qiu team showed that, while all other KlpA-like motor proteins are believed to move in only one direction on the microtubule track, KlpA has a “reverse” gear that allows it to go in different directions. This enables KlpA to behave differently in when it is operating at different locations within the mitotic spindle.

The discovery of a reverse gear in KlpA has the potential to shed light on similar KlpA-like proteins in mammals that are implicated in cancer proliferation.  Furthermore, understanding the design principle behind the bidirectional motion of KlpA may also guide the engineering of motor protein-based molecular devices for more controlled and targeted drug delivery.

Based on an article in The Spectrometer by Heidi Schellman.

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