Deformations Within Moving Kinetochores Reveal Different Sites of Active and Passive Force Generation

Abstract

Never Let Me Go Kinetochores are the structures within chromosomes that interact with the microtubules of the mitotic spindle during mitosis. By measuring the deformation of individual kinetochores in live mammalian cells, Dumont et al. (p. 355 , published online 21 June) asked, how do kinetochores harness the free energy of microtubule depolymerization without losing grip of microtubules? Kinetochores contacted microtubules using two distinct mechanical interfaces: an active, force-generating interface near the microtubule tip, and a passive, frictional interface at least 20 nanometers away along the microtubule lattice. The separate active and passive interfaces allowed for intermittent force generation and persistent microtubule attachment—both required for accurate chromosome segregation.