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XB-ART-56629
Elife January 1, 2020; 9

Biochemical reconstitution of branching microtubule nucleation.

Alfaro-Aco R , Thawani A , Petry S .


Abstract
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 Xenopus laevis 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.

PubMed ID: 31933480
PMC ID: PMC6959992
Article link: Elife
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: ckap5 mapre1 tpx2


Article Images: [+] show captions
References [+] :
Alfaro-Aco, Structural analysis of the role of TPX2 in branching microtubule nucleation. 2017, Pubmed, Xenbase