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J Cell Biol. 2017 Jun 5;216(6):1641-1657. doi: 10.1083/jcb.201610090. Epub 2017 May 16.

TOG-tubulin binding specificity promotes microtubule dynamics and mitotic spindle formation.

Author information

1
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599.
2
Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, NC 27599.
3
Program in Molecular and Cellular Biophysics, University of North Carolina, Chapel Hill, NC 27599 kslep@bio.unc.edu.
4
Department of Biology, University of North Carolina, Chapel Hill, NC 27599.

Abstract

XMAP215, CLASP, and Crescerin use arrayed tubulin-binding tumor overexpressed gene (TOG) domains to modulate microtubule dynamics. We hypothesized that TOGs have distinct architectures and tubulin-binding properties that underlie each family's ability to promote microtubule polymerization or pause. As a model, we investigated the pentameric TOG array of a Drosophila melanogaster XMAP215 member, Msps. We found that Msps TOGs have distinct architectures that bind either free or polymerized tubulin, and that a polarized array drives microtubule polymerization. An engineered TOG1-2-5 array fully supported Msps-dependent microtubule polymerase activity. Requisite for this activity was a TOG5-specific N-terminal HEAT repeat that engaged microtubule lattice-incorporated tubulin. TOG5-microtubule binding maintained mitotic spindle formation as deleting or mutating TOG5 compromised spindle architecture and increased the mitotic index. Mad2 knockdown released the spindle assembly checkpoint triggered when TOG5-microtubule binding was compromised, indicating that TOG5 is essential for spindle function. Our results reveal a TOG5-specific role in mitotic fidelity and support our hypothesis that architecturally distinct TOGs arranged in a sequence-specific order underlie TOG array microtubule regulator activity.

PMID:
28512144
PMCID:
PMC5461023
DOI:
10.1083/jcb.201610090
[Indexed for MEDLINE]
Free PMC Article

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