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Mol Biol Cell. 2015 Jan 15;26(2):229-37. doi: 10.1091/mbc.E14-06-1125. Epub 2014 Nov 19.

The outer kinetochore protein KNL-1 contains a defined oligomerization domain in nematodes.

Author information

1
Whitehead Institute for Biomedical Research, Cambridge, MA 02142 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139.
2
Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093.
3
Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454.
4
Whitehead Institute for Biomedical Research, Cambridge, MA 02142 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139 icheese@wi.mit.edu.

Abstract

The kinetochore is a large, macromolecular assembly that is essential for connecting chromosomes to microtubules during mitosis. Despite the recent identification of multiple kinetochore components, the nature and organization of the higher-order kinetochore structure remain unknown. The outer kinetochore KNL-1/Mis12 complex/Ndc80 complex (KMN) network plays a key role in generating and sensing microtubule attachments. Here we demonstrate that Caenorhabditis elegans KNL-1 exists as an oligomer, and we identify a specific domain in KNL-1 responsible for this activity. An N-terminal KNL-1 domain from both C. elegans and the related nematode Caenorhabditis remanei oligomerizes into a decameric assembly that appears roughly circular when visualized by electron microscopy. On the basis of sequence and mutational analysis, we identify a small hydrophobic region as responsible for this oligomerization activity. However, mutants that precisely disrupt KNL-1 oligomerization did not alter KNL-1 localization or result in the loss of embryonic viability based on gene replacements in C. elegans. In C. elegans, KNL-1 oligomerization may coordinate with other kinetochore activities to ensure the proper organization, function, and sensory capabilities of the kinetochore-microtubule attachment.

PMID:
25411336
PMCID:
PMC4294671
DOI:
10.1091/mbc.E14-06-1125
[Indexed for MEDLINE]
Free PMC Article

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