Kinesin Kip2 enhances microtubule growth in vitro through length-dependent feedback on polymerization and catastrophe
- Max Planck Institute of Molecular Cell Biology and Genetics, Germany
- Yale University, United States
- Imperial College London, United Kingdom
- Eberhard-Karls-Universität Tübingen, Germany
- Centre de Recherche de Biochimie Macromoléculaire, France
Abstract
The size and position of mitotic spindles is determined by the lengths of their constituent microtubules. Regulation of microtubule length requires feedback to set the balance between growth and shrinkage. Whereas negative feedback mechanisms for microtubule length control, based on depolymerizing kinesins and severing proteins, have been studied extensively, positive feedback mechanisms are not known. Here we report that the budding yeast kinesin Kip2 is a microtubule polymerase and catastrophe inhibitor in vitro that uses its processive motor activity as part of a feedback loop to further promote microtubule growth. Positive feedback arises because longer microtubules bind more motors, which walk to the ends where they further reinforce growth and inhibit catastrophe. We propose that positive feedback, common in biochemical pathways to switch between signaling states, can also be used in a mechanical signaling pathway to switch between structural states, in this case between short and long polymers.
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© 2015, Hibbel et al.
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Kinesin Kip2 enhances microtubule growth in vitro through length-dependent feedback on polymerization and catastrophe
eLife 4:e10542.
https://doi.org/10.7554/eLife.10542
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