Deformations within moving kinetochores reveal different sites of active and passive force generation.
Kinetochores mediate chromosome segregation at mitosis. They are thought to contain both active, force-producing and passive, frictional interfaces with microtubules whose relative locations have been unclear. We inferred mechanical deformation within single kinetochores during metaphase oscillations by measuring average separations between fluorescently labeled kinetochore subunits in living cells undergoing mitosis. Inter-subunit distances were shorter in kinetochores moving toward poles than in those moving away. Inter-subunit separation decreased abruptly when kinetochores switched to poleward movement and decreased further when pulling force increased, suggesting that active force generation during poleward movement compresses kinetochores. The data revealed an active force-generating interface within kinetochores and a separate passive frictional interface located at least 20 nanometers away poleward. Together, these interfaces allow persistent attachment with intermittent active force generation.
Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA. sophie.dumont@ucsf.edu
Sophie
S
Dumont
E D
ED
Salmon
Timothy J
TJ
Mitchison
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation / Q000235:genetics / Q000502:physiology*; D018386:Kinetochores / Q000737:chemistry / Q000502:physiology*; D055595:Mechanical Phenomena; D008677:Metaphase; D009038:Motion; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D048328:Potoroidae
D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; C060905:centromere protein C