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bioRxiv · 10.1101/093054

The centrosome is a selective phase that nucleates microtubules by concentrating tubulin

Woodruff, J. B.·Ferreira Gomes, B.·Widlund, P. O.·Mahamid, J.·Hyman, A. A.
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Abstract

Centrosomes are non-membrane-bound compartments that nucleate microtubule arrays. They consist of nanometer-scale centrioles surrounded by a micron-scale, dynamic assembly of protein called the pericentriolar material (PCM). To study how PCM forms a spherical compartment that nucleates microtubules, we reconstituted PCM-dependent microtubule nucleation in vitro using recombinant C.elegans proteins. We found that macromolecular crowding drives phase separation of the key PCM scaffold protein SPD-5 into spherical droplets that morphologically and dynamically resemble in vivo PCM. These SPD-5 droplets recruited the microtubule polymerase ZYG-9 (XMAP215 homologue) and the microtubule-stabilizing protein TPXL-1 (TPX2 homologue). Together, these three proteins concentrated tubulin ~4- fold over background, which was sufficient to reconstitute nucleation of microtubule asters in vitro. Our results suggest that in vivo PCM is a selective phase that organizes microtubule arrays through localized concentration of tubulin by microtubule effector proteins.\n\nOne Sentence SummaryPhase separation of C. elegans centrosome proteins drive the formation of micron-sized microtubule organizing centers.

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Woodruff, J. B., Ferreira Gomes, B., Widlund, P. O., Mahamid, J., Hyman, A. A.. 2016-12-10. The centrosome is a selective phase that nucleates microtubules by concentrating tubulin. https://doi.org/10.1101/093054

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