title: KNL-1 directs assembly of the microtubule-binding interface of the kinetochore in C. elegans.
abstract: Segregation of the replicated genome during cell division requires kinetochores, mechanochemical organelles that assemble on mitotic chromosomes to connect them to spindle microtubules. CENP-A, a histone H3 variant, and CENP-C, a conserved structural protein, form the DNA-proximal foundation for kinetochore assembly. Using RNA interference-based genomics in Caenorhabditis elegans, we identified KNL-1, a novel kinetochore protein whose depletion, like that of CeCENP-A or CeCENP-C, leads to a "kinetochore-null" phenotype. KNL-1 is downstream of CeCENP-A and CeCENP-C in a linear assembly hierarchy. In embryonic extracts, KNL-1 exhibits substoichiometric interactions with CeCENP-C and forms a near-stoichiometric complex with CeNDC-80 and HIM-10, the C. elegans homologs of Ndc80p/HEC1p and Nuf2p-two widely conserved outer kinetochore components. However, CeNDC-80 and HIM-10 are not functionally equivalent to KNL-1 because their inhibition, although preventing formation of a mechanically stable kinetochore-microtubule interface and causing chromosome missegregation, does not result in a kinetochore-null phenotype. The greater functional importance of KNL-1 may be due to its requirement for targeting multiple components of the outer kinetochore, including CeNDC-80 and HIM-10. Thus, KNL-1 plays a central role in translating the initiation of kinetochore assembly by CeCENP-A and CeCENP-C into the formation of a functional microtubule-binding interface.
authors.affiliation: Max Planck Institute for Molecular Cell Biology and Genetics (MPI-CBG), Dresden 01307, Germany.
authors.forename: Arshad
authors.initials: A
authors.lastname: Desai
authors.forename: Sonja
authors.initials: S
authors.lastname: Rybina
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller-Reichert
authors.forename: Andrej
authors.initials: A
authors.lastname: Shevchenko
authors.forename: Anna
authors.initials: A
authors.lastname: Shevchenko
authors.forename: Anthony
authors.initials: A
authors.lastname: Hyman
authors.forename: Karen
authors.initials: K
authors.lastname: Oegema
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens; D001665:Binding Sites; D017173:Caenorhabditis elegans / Q000166:cytology* / Q000196:embryology / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D000076247:Centromere Protein A; D051936:Centromere Protein B; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D004625:Embryo, Nonmammalian; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D018386:Kinetochores / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D001324:Autoantigens; C000619700:CENPA protein, human; D029742:Caenorhabditis elegans Proteins; D018797:Cell Cycle Proteins; D000076247:Centromere Protein A; D051936:Centromere Protein B; D002868:Chromosomal Proteins, Non-Histone; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C478661:HIM-10 protein, C elegans; C478660:KNL-1 protein, C elegans; D008869:Microtubule-Associated Proteins; C112472:NDC80 protein, S cerevisiae; C120529:NDC80 protein, human; C490197:NUF2 protein, human; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C060905:centromere protein C