JCB 175:25 (2006/10)
Hernando Sosa @ Albert Einstein College of Medicine
In this paper, authors demonstrate by EMs that kinesin-13 proteins form oligomeric rings and spirals around microtubules. Several kinesins in this family were tested, including KLP10A and KLP59C in Drosophila and MCAK from hamster. Rings only formed in the presence of both microtubules and kinesin-13 proteins, but the formation is independent of the nucleotide condition of the polymerized tubulin. Authors suggested the rungs could function as a movable sleeve around the microtubule, similar to the Dam1-DASH kinetochore complex in yeast.
Several people in out lab said they don’t understand why this paper could be published on JCB. The main reason is this paper didn't provide details of the molecular mechanism. However, I like this paper. This paper is small but clear. The structural novelty obviously is the point to sell. Kinesin-13 proteins have different microtubule depolymerizing function to other kinesin proteins. Now this paper showed the structure is also different to other kinesin motors. The EM data are solid and live imaging experiments are good too. Reasonably authors thought kinesin-13s might work as Dam1 complex in yeast since the Dam1 homologous genes in higher eukaryotes have not been found. Even in the Dam1 paper, the model was also built on in vitro experiment and has no solid in vivo data supported it. So the sleeve model is still a juicy hypothesis. Many people, including Tim, love it but it is not carved on the stone yet. However, realized kinesin-13s formed ring structure is still very helpful for people to study its possible molecular mechanism in the future.
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