National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
GM051487
米国
Howard Hughes Medical Institute (HHMI)
米国
Cancer Research UK
FC001163
英国
Medical Research Council (MRC, United Kingdom)
FC001163
英国
Wellcome Trust
FC001163
英国
引用
ジャーナル: Elife / 年: 2017 タイトル: Structural insight into TPX2-stimulated microtubule assembly. 著者: Rui Zhang / Johanna Roostalu / Thomas Surrey / Eva Nogales / 要旨: During mitosis and meiosis, microtubule (MT) assembly is locally upregulated by the chromatin-dependent Ran-GTP pathway. One of its key targets is the MT-associated spindle assembly factor TPX2. The ...During mitosis and meiosis, microtubule (MT) assembly is locally upregulated by the chromatin-dependent Ran-GTP pathway. One of its key targets is the MT-associated spindle assembly factor TPX2. The molecular mechanism of how TPX2 stimulates MT assembly remains unknown because structural information about the interaction of TPX2 with MTs is lacking. Here, we determine the cryo-electron microscopy structure of a central region of TPX2 bound to the MT surface. TPX2 uses two flexibly linked elements ('ridge' and 'wedge') in a novel interaction mode to simultaneously bind across longitudinal and lateral tubulin interfaces. These MT-interacting elements overlap with the binding site of importins on TPX2. Fluorescence microscopy-based in vitro reconstitution assays reveal that this interaction mode is critical for MT binding and facilitates MT nucleation. Together, our results suggest a molecular mechanism of how the Ran-GTP gradient can regulate TPX2-dependent MT formation.