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Rapid microtubule self-assembly kinetics |
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| Authors: | Gardner Melissa K Charlebois Blake D Jánosi Imre M Howard Jonathon Hunt Alan J Odde David J |
| Institution: | 1 Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA 2 Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany 3 Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA 4 Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA 5 Department of Physics of Complex Systems, Loránd Eötvös University, Budapest, Hungary |
| Abstract: | Microtubule assembly is vital for many fundamental cellular processes. Current models for microtubule assembly kinetics assume that the subunit dissociation rate from a microtubule tip is independent of free subunit concentration. Total-Internal-Reflection-Fluorescence (TIRF) microscopy experiments and data from a laser tweezers assay that measures in vitro microtubule assembly with nanometer resolution, provides evidence that the subunit dissociation rate from a microtubule tip increases as the free subunit concentration increases. These data are consistent with a two-dimensional model for microtubule assembly, and are explained by a shift in microtubule tip structure from a relatively blunt shape at low free concentrations to relatively tapered at high free concentrations. We find that because both the association and the dissociation rates increase at higher free subunit concentrations, the kinetics of microtubule assembly are an order-of-magnitude higher than currently estimated in the literature. |
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