How Do Cancerous Microtubules Affect the Dynamic Properties of Kinesin Motors?
Yonggun Jun1*
1Department of Physics, National Central University, Taoyuan, Taiwan
* presenting author:Yonggun Jun,
Kinesin motor proteins play an important role in intracellular cargos transport and mitosis of cells. While there have been many studies of dynamic properties of kinesin motors along the microtubule (MT) in the in vitro experiments, functional change of kinesins due to tubulin isoform differences between cell types are mostly unexplored. Of particular interest is transport and force production by Eg5 along microtubules polymerized from tubulin purified from MCF7 breast cancer cells because the Eg5 motor contributes critically to mitosis, and is often upregulated in cancer. We quantified the in vitro motility characteristics of single Eg5 motor along these two types of microtubules, combining the utilization of an optical trapping technique. On MCF7 MTs, processivity of Eg5 are significantly reduced, although velocity is only slightly altered. We then investigated the detachment force and found that Eg5’s function changed dramatically on MCF7 MTs: its average detachment force was reduced and its force–velocity curve was different. This result indicates that slow velocity of Eg5 along the cancer cell MTs improves the collective motion under high load such as spindle-mediated chromosome separation, possibly contributing to faster mitosis in cancer cells.

Keywords: Kinesin-1, Eg5, Microtubule, Optical trapping, Tubulin isotype