Microtubule munching

A yeast kinesin rapidly munches long microtubules, but its munching speed slows as the microtubules get shorter, report Vladimir Varga, Jonathon Howard, and colleagues (Max Planck Institute, Dresden, Germany). Along with Mohan Gupta, David Pellman, and colleagues (Harvard, Boston, MA), the team also shows that this kinesin-8, called Kip3p, paradoxically eats away at the growing ends of microtubules.

Microtubule length must be tightly controlled for cell functions as diverse as transport, motility, and division. In vitro studies by both groups showed that Kip3p binds all along the length of microtubules, but then motors along to accumulate at their plus ends, where it functions as a depolymerase.

Varga et al. found that Kip3p had a bigger appetite for longer microtubules, as these were devoured more rapidly than short microtubules. The authors...