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Single-Cell Biophysics: Measurement, Modulation, and Modeling
Poster Abstracts
113
30-POS
Board 15
Mechanism of Microtubule Growth Promotion by the Kinesin Kip2
Pei-Tzu Huang
, Anneke Hibbel, Jonathan Howard.
Yale University, New Haven, CT, USA.
Microtubules are dynamic structures formed by α- and β-tubulin heterodimers. They play
essential roles in the cell cycle, cell motility, and cellular transport, and are regulated by a
diverse array of microtubule associated proteins (MAPs). One of these important MAPs is the
budding yeast kinesin Kip2. Kip2 can translocate processively along the microtubules to the
plus-end, and is involved in mitotic spindle positioning and stabilization of microtubules during
cell cycle telophase. Previously, it was shown that Kip2 regulates microtubules indirectly by
transporting microtubule positive regulators Bik1 and dynein to the microtubule plus end;
recently, it was shown that Kip2 regulates microtubules directly by acting as a polymerase.
However, the molecular mechanism by which Kip2 polymerizes microtubules is unclear. One of
the hypotheses is that Kip2 functions as a processive polymerase that adds multiple tubulin
heterodimers to the microtubule plus end. In this case, it is expected that there are multiple
tubulin binding sites on each Kip2 molecule. Therefore, I aim to map the putative binding
interfaces of Kip2 with tubulin heterodimers by using gel filtration binding assays, and perform
microtubule dynamic assays of full-length and truncated Kip2 to identify the tubulin binding
sites involved in the polymerization mechanism.