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Science. 2019 Jan 18;363(6424):285-288. doi: 10.1126/science.aav2567.

Flagellar microtubule doublet assembly in vitro reveals a regulatory role of tubulin C-terminal tails.

Author information

1
Department of Cell Biology, Sciences III, University of Geneva, Geneva, Switzerland.
2
Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Vestec, Czech Republic.
3
Faculty of Mathematics and Physics, Charles University in Prague, Prague, Czech Republic.
4
Institut Curie, PSL Research University, CNRS UMR 9187 - INSERM U1196, Paris-Saclay University, F-91405 Orsay, France.
5
Interdisciplinary Centre for Electron Microscopy, Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland.
6
Department of Cell Biology, Sciences III, University of Geneva, Geneva, Switzerland. virginie.hamel@unige.ch paul.guichard@unige.ch.

Abstract

Microtubule doublets (MTDs), consisting of an incomplete B-microtubule at the surface of a complete A-microtubule, provide a structural scaffold mediating intraflagellar transport and ciliary beating. Despite the fundamental role of MTDs, the molecular mechanism governing their formation is unknown. We used a cell-free assay to demonstrate a crucial inhibitory role of the carboxyl-terminal (C-terminal) tail of tubulin in MTD assembly. Removal of the C-terminal tail of an assembled A-microtubule allowed for the nucleation of a B-microtubule on its surface. C-terminal tails of only one A-microtubule protofilament inhibited this side-to-surface tubulin interaction, which would be overcome in vivo with binding protein partners. The dynamics of B-microtubule nucleation and its distinctive isotropic elongation was elucidated by using live imaging. Thus, inherent interaction properties of tubulin provide a structural basis driving flagellar MTD assembly.

PMID:
30655442
DOI:
10.1126/science.aav2567

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