KNL-1 directs assembly of the microtubule-binding interface of the kinetochore in C. elegans.
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.
Desai
Arshad
A
Max Planck Institute for Molecular Cell Biology and Genetics (MPI-CBG), Dresden 01307, Germany.
Rybina
Sonja
S
Müller-Reichert
Thomas
T
Shevchenko
Andrej
A
Shevchenko
Anna
A
Hyman
Anthony
A
Oegema
Karen
K
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
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