title: The outer kinetochore protein KNL-1 contains a defined oligomerization domain in nematodes.
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.
authors.affiliation: Whitehead Institute for Biomedical Research, Cambridge, MA 02142 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: David M
authors.initials: DM
authors.lastname: Kern
authors.affiliation: Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093.
authors.forename: Taekyung
authors.initials: T
authors.lastname: Kim
authors.affiliation: Howard Hughes Medical Institute, Brandeis University, Waltham, MA 02454.
authors.forename: Mike
authors.initials: M
authors.lastname: Rigney
authors.affiliation: Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093.
authors.forename: Neil
authors.initials: N
authors.lastname: Hattersley
authors.affiliation: Ludwig Institute for Cancer Research, Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA 92093.
authors.forename: Arshad
authors.initials: A
authors.lastname: Desai
authors.affiliation: Whitehead Institute for Biomedical Research, Cambridge, MA 02142 Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139 icheese@wi.mit.edu.
authors.forename: Iain M
authors.initials: IM
authors.lastname: Cheeseman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D001665:Binding Sites / Q000235:genetics; D002107:Caenorhabditis / Q000235:genetics / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000235:genetics; D020090:Chromosome Segregation / Q000235:genetics; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D018386:Kinetochores / Q000378:metabolism*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018613:Microscopy, Confocal; D046529:Microscopy, Electron, Transmission; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D059008:Time-Lapse Imaging / Q000379:methods
chemical_list: D029742:Caenorhabditis elegans Proteins; C478660:KNL-1 protein, C elegans; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins