Biology Department, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Nat Commun. 2016 Oct 20;7:13221. doi: 10.1038/ncomms13221.
High-fidelity transmission of the genome through cell division requires that all sister kinetochores bind to dynamic microtubules (MTs) from opposite spindle poles. The application of opposing forces to this bioriented configuration produces tension that stabilizes kinetochore-microtubule (kt-MT) attachments. Defining the magnitude of force that is applied to kinetochores is central to understanding the mechano-molecular underpinnings of chromosome segregation; however, existing kinetochore force measurements span orders of magnitude. Here we measure kinetochore forces by engineering two calibrated force sensors into the Drosophila kinetochore protein centromere protein (CENP)-C. Measurements of both reporters indicate that they are, on average, under ∼1-2 piconewtons (pNs) of force at metaphase. Based on estimates of the number of CENP-C molecules and MTs per Drosophila kinetochore and envisioning kinetochore linkages arranged such that they distribute forces across them, we propose that kinetochore fibres (k-fibres) exert hundreds of pNs of poleward-directed force to bioriented kinetochores.
通过细胞分裂实现基因组的高保真传递，需要所有姐妹动粒与来自纺锤体相对两极的动态微管（MT）结合。将相反的力施加到这个双取向的构象上，会产生张力，从而稳定动粒-MT（kt-MT）附着。确定作用在动粒上的力的大小是理解染色体分离的机械分子基础的核心；然而，现有的动粒力测量跨度数量级。在这里，我们通过在果蝇动粒蛋白着丝粒蛋白（CENP）-C 中构建两个校准力传感器来测量动粒力。两个报告器的测量值表明，在中期它们平均受到约 1-2 皮牛顿（pN）的力。根据每个果蝇动粒的 CENP-C 分子和 MT 的数量的估计，并设想动粒连接以使其在它们之间分布力，我们提出动粒纤维（k-纤维）向双取向的动粒施加数百皮牛顿的指向极的力。
