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Dev Cell. 2016 May 23;37(4):362-376. doi: 10.1016/j.devcel.2016.04.024.

Centriolar CPAP/SAS-4 Imparts Slow Processive Microtubule Growth.

Author information

1
Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland.
2
Cell Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands.
3
Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
4
Bio-EM Facility, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
5
Cell Biology, Faculty of Science, Utrecht University, 3584 CH Utrecht, The Netherlands. Electronic address: a.akhmanova@uu.nl.
6
Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland. Electronic address: pierre.gonczy@epfl.ch.
7
Laboratory of Biomolecular Research, Department of Biology and Chemistry, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland. Electronic address: michel.steinmetz@psi.ch.

Abstract

Centrioles are fundamental and evolutionarily conserved microtubule-based organelles whose assembly is characterized by microtubule growth rates that are orders of magnitude slower than those of cytoplasmic microtubules. Several centriolar proteins can interact with tubulin or microtubules, but how they ensure the exceptionally slow growth of centriolar microtubules has remained mysterious. Here, we bring together crystallographic, biophysical, and reconstitution assays to demonstrate that the human centriolar protein CPAP (SAS-4 in worms and flies) binds and "caps" microtubule plus ends by associating with a site of β-tubulin engaged in longitudinal tubulin-tubulin interactions. Strikingly, we uncover that CPAP activity dampens microtubule growth and stabilizes microtubules by inhibiting catastrophes and promoting rescues. We further establish that the capping function of CPAP is important to limit growth of centriolar microtubules in cells. Our results suggest that CPAP acts as a molecular lid that ensures slow assembly of centriolar microtubules and, thereby, contributes to organelle length control.

KEYWORDS:

CPAP/SAS-4; Centrioles; X-ray crystallography; human cells; in vitro reconstitutions; microtubules

PMID:
27219064
PMCID:
PMC4884677
DOI:
10.1016/j.devcel.2016.04.024
[Indexed for MEDLINE]
Free PMC Article

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