Biochemical reconstitution of branching microtubule nucleation.

TitleBiochemical reconstitution of branching microtubule nucleation.
Publication TypeJournal Article
Year of Publication2020
AuthorsAlfaro-Aco, R, Thawani, A, Petry, S
Date Published2020 Jan 14
KeywordsAnimals, Brain, Cattle, Cell Cycle Proteins, Escherichia coli, Gene Expression Regulation, Humans, Microscopy, Fluorescence, Microtubule Proteins, Microtubule-Associated Proteins, Microtubules, Mitosis, Multiprotein Complexes, Spindle Apparatus, Tubulin, Xenopus laevis, Xenopus Proteins

<p>Microtubules are nucleated from specific locations at precise times in the cell cycle. However, the factors that constitute these microtubule nucleation pathways and their mode of action still need to be identified. Using purified proteins we biochemically reconstitute branching microtubule nucleation, which is critical for chromosome segregation. We found that besides the microtubule nucleator gamma-tubulin ring complex (γ-TuRC), the branching effectors augmin and TPX2 are required to efficiently nucleate microtubules from pre-existing microtubules. TPX2 has the unexpected capacity to directly recruit γ-TuRC as well as augmin, which in turn targets more γ-TuRC along the microtubule lattice. TPX2 and augmin enable γ-TuRC-dependent microtubule nucleation at preferred branching angles of less than 90 degrees from regularly-spaced patches along microtubules. This work provides a blueprint for other microtubule nucleation pathways and helps explain how microtubules are generated in the spindle.</p>

Alternate JournalElife
PubMed ID31933480
PubMed Central IDPMC6959992
Grant ListT32 GM007388 / GM / NIGMS NIH HHS / United States
DP2 GM123493 / GM / NIGMS NIH HHS / United States