title: The Ndc80 internal loop is required for recruitment of the Ska complex to establish end-on microtubule attachment to kinetochores.
abstract: The Ndc80 complex establishes end-on attachment of kinetochores to microtubules, which is essential for chromosome segregation. The Ndc80 subunit is characterized by an N-terminal region that binds directly to microtubules, and a long coiled-coil region that interacts with Nuf2. A loop region in Ndc80 that generates a kink in the structure disrupts the long coiled-coil region but the exact function of this loop, has until now, not been clear. Here we show that this loop region is essential for end-on attachment of kinetochores to microtubules in human cells. Cells expressing loop mutants of Ndc80 are unable to align the chromosomes, and stable kinetochore fibers are absent. Through quantitative mass spectrometry and immunofluorescence we found that the binding of the spindle and kinetochore associated (Ska) complex depends on the loop region, explaining why end-on attachment is defective. This underscores the importance of the Ndc80 loop region in coordinating chromosome segregation through the recruitment of specific proteins to the kinetochore.
authors.affiliation: The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Gang
authors.initials: G
authors.lastname: Zhang
authors.forename: Christian D
authors.initials: CD
authors.lastname: Kelstrup
authors.forename: Xiao-Wen
authors.initials: XW
authors.lastname: Hu
authors.forename: Mathilde J
authors.initials: MJ
authors.lastname: Kaas Hansen
authors.forename: Martin R
authors.initials: MR
authors.lastname: Singleton
authors.forename: Jesper V
authors.initials: JV
authors.lastname: Olsen
authors.forename: Jakob
authors.initials: J
authors.lastname: Nilsson
mesh_terms: D000595:Amino Acid Sequence; D020090:Chromosome Segregation; D002877:Chromosomes, Human / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D003598:Cytoskeletal Proteins; D005455:Fluorescent Antibody Technique; D006801:Humans; D018386:Kinetochores / Q000378:metabolism*; D013058:Mass Spectrometry / Q000379:methods; D008677:Metaphase; D008870:Microtubules / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D021381:Protein Transport; D034622:RNA Interference; D020539:Sequence Analysis, Protein / Q000379:methods
chemical_list: D003598:Cytoskeletal Proteins; D046912:Multiprotein Complexes; C120529:NDC80 protein, human; D009687:Nuclear Proteins