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Self-Assembly of Microtubule Tactoids
Published on: June 23, 2022
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Structural insight into TPX2-stimulated microtubule assembly
Rui Zhang1, Johanna Roostalu2, Thomas Surrey2
1Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, United States.
Elife
|November 10, 2017
Summary
Researchers uncovered how TPX2 protein interacts with microtubules (MTs) to promote cell division. This structural insight reveals a novel binding mechanism critical for MT nucleation and regulation by the Ran-GTP pathway.
Area of Science:
- Cell Biology
- Structural Biology
- Biochemistry
Background:
- Microtubule (MT) assembly is crucial for cell division (mitosis and meiosis).
- The Ran-GTP pathway regulates MT assembly, with TPX2 being a key target.
- The structural basis for TPX2's interaction with MTs and its mechanism of action were previously unknown.
Purpose of the Study:
- To determine the structural mechanism by which TPX2 stimulates microtubule assembly.
- To elucidate how TPX2's interaction with microtubules is regulated.
Main Methods:
- Cryo-electron microscopy (cryo-EM) to determine the structure of TPX2 bound to MTs.
- Fluorescence microscopy-based in vitro reconstitution assays to study MT binding and nucleation.
Main Results:
- The cryo-EM structure reveals TPX2 binds MTs via two flexibly linked elements ('ridge' and 'wedge') at tubulin interfaces.
- This novel interaction mode is essential for MT binding and nucleation.
- The MT-binding site on TPX2 overlaps with the importin binding site, suggesting regulatory crosstalk.
Conclusions:
- A molecular mechanism for TPX2-mediated MT nucleation is proposed.
- The findings provide insight into how the Ran-GTP gradient regulates MT formation during cell division.
- Structural understanding of TPX2-MT interaction opens avenues for studying MT dynamics in various cellular processes.
Keywords:
Ran-GTPbiochemistrybiophysicscell divisioncryo-EMdynamic instabilityhumanmicrotubulenucleationstructural biologyMore Related Videos
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