A liquid +TIP-network drives microtubule dynamics through tubulin condensation [article]

Julie Miesch, Robert T. Wimbish, Marie-Claire Velluz, Charlotte Aumeier
2021 bioRxiv   pre-print
Tubulin dimers assemble into a dynamic microtubule network throughout the cell. Microtubule dynamics and network organization must be precisely tuned for the microtubule cytoskeleton to regulate a dazzling array of dynamic cell behaviors. Since tubulin concentration determines microtubule growth, we studied here a novel regulatory mechanism of microtubule dynamics: local tubulin condensation. We discovered that two microtubule tip-binding proteins, CLIP-170 and EB3, undergo phase separation and
more » ... form an EB3/CLIP-170 droplet at the growing microtubule tip. We prove that this +TIP-droplet has the capacity to locally condense tubulin. This process of tubulin co-condensation is spatially initiated at the microtubule tip and temporally regulated to occur only when there is tip growth. Tubulin condensation at the growing microtubule tip increases growth speeds three-fold and strongly reduces depolymerization events. With this work we establish a new mechanism to regulate microtubule dynamics by enrichment of tubulin at strategically important locations: the growing microtubule tips.
doi:10.1101/2021.09.13.459419 fatcat:zglplxyp2zeapkl7lcwnsbfbku