title: The structure of purified kinetochores reveals multiple microtubule-attachment sites.
abstract: Chromosomes must be accurately partitioned to daughter cells to prevent aneuploidy, a hallmark of many tumors and birth defects. Kinetochores are the macromolecular machines that segregate chromosomes by maintaining load-bearing attachments to the dynamic tips of microtubules. Here, we present the structure of isolated budding-yeast kinetochore particles, as visualized by EM and electron tomography of negatively stained preparations. The kinetochore appears as an ~126-nm particle containing a large central hub surrounded by multiple outer globular domains. In the presence of microtubules, some particles also have a ring that encircles the microtubule. Our data, showing that kinetochores bind to microtubules via multivalent attachments, lay the foundation to uncover the key mechanical and regulatory mechanisms by which kinetochores control chromosome segregation and cell division.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, Washington, USA.
authors.forename: Shane
authors.initials: S
authors.lastname: Gonen
authors.forename: Bungo
authors.initials: B
authors.lastname: Akiyoshi
authors.forename: Matthew G
authors.initials: MG
authors.lastname: Iadanza
authors.forename: Dan
authors.initials: D
authors.lastname: Shi
authors.forename: Nicole
authors.initials: N
authors.lastname: Duggan
authors.forename: Sue
authors.initials: S
authors.lastname: Biggins
authors.forename: Tamir
authors.initials: T
authors.lastname: Gonen
mesh_terms: D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D018386:Kinetochores / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure*; D008870:Microtubules / Q000378:metabolism* / Q000648:ultrastructure; D008958:Models, Molecular; D004718:Saccharomycetales / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D005656:Fungal Proteins