CAMSAP2 organizes a γ-tubulin-independent microtubule nucleation centre through phase separation

eLife

Satoshi Kikkawa¹  Yoshiaki Sakihama²  Takahiro Shimizu²  Shinsuke Niwa³  Ayako Sakamoto⁴  Kazuhiro Aoyama⁵  Ryo Nitta⁵  Naoki Sakai⁵  Tsuyoshi Imasaki⁵  Yumiko Saijo-Hamano⁵  Masatoshi Takeichi⁵  Hideki Shigematsu⁶  Mari Aoki⁷  Shinya Taguchi⁸  Yosuke Yamagishi⁸  Eriko Nitta⁸  Mikako Shirouzu⁸  Tomiyoshi Setsu⁹  Kaoru Mitsuoka⁹  Yuri Tomabechi^1,10 

[1] JST, PRESTO, Saitama, Japan;Japan Synchrotron Radiation Research Institute (JASRI), Hyogo, Japan;RIKEN Center for Biosystems Dynamics Research, Yokohama, Japan;Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Osaka, Japan;Division of Structural Medicine and Anatomy, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Kobe, Japan;Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Japan;Materials and Structural Analysis, Thermo Fisher Scientific, Tokyo, Japan;RIKEN Center for Biosystems Dynamics Research, Yokohama, Japan;RIKEN SPring-8 Center, Hyogo, Japan;Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Osaka, Japan;

关键词: microtubule;    CAMSAP;    cryo-EM;    TIRF;    nucleation;    LLPS;   

DOI  :  10.7554/eLife.77365

来源: DOAJ

【 摘 要 】

Microtubules are dynamic polymers consisting of αβ-tubulin heterodimers. The initial polymerization process, called microtubule nucleation, occurs spontaneously via αβ-tubulin. Since a large energy barrier prevents microtubule nucleation in cells, the γ-tubulin ring complex is recruited to the centrosome to overcome the nucleation barrier. However, a considerable number of microtubules can polymerize independently of the centrosome in various cell types. Here, we present evidence that the minus-end-binding calmodulin-regulated spectrin-associated protein 2 (CAMSAP2) serves as a strong nucleator for microtubule formation by significantly reducing the nucleation barrier. CAMSAP2 co-condensates with αβ-tubulin via a phase separation process, producing plenty of nucleation intermediates. Microtubules then radiate from the co-condensates, resulting in aster-like structure formation. CAMSAP2 localizes at the co-condensates and decorates the radiating microtubule lattices to some extent. Taken together, these in vitro findings suggest that CAMSAP2 supports microtubule nucleation and growth by organizing a nucleation centre as well as by stabilizing microtubule intermediates and growing microtubules.

【 授权许可】

Unknown