Janczyk Paweł Ł, Skorupka Katarzyna A, Tooley John G, Matson Daniel R, Kestner Cortney A, West Thomas, Pornillos Owen, Stukenberg P Todd
Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, 1340 Jefferson Park Avenue, Pinn Hall, Room 6014, Charlottesville, VA 22908, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.
Dev Cell. 2017 May 22;41(4):438-449.e4. doi: 10.1016/j.devcel.2017.04.020.
Yeast use the ring-shaped Dam1 complex to slide down depolymerizing microtubules to move chromosomes, but current models suggest that other eukaryotes do not have a sliding ring. We visualized Ndc80 and Ska complexes on microtubules by electron microscopic tomography to identify the structure of the human kinetochore-microtubule attachment. Ndc80 recruits the Ska complex so that the V shape of the Ska dimer interacts along protofilaments. We identify a mutant of the Ndc80 tail that is deficient in Ska recruitment to kinetochores and in orienting Ska along protofilaments in vitro. This mutant Ndc80 binds microtubules with normal affinity but is deficient in clustering along protofilaments. We propose that Ska is recruited to kinetochores by clusters of Ndc80 proteins and that our structure of Ndc80 and Ska complexes on microtubules suggests a mechanism for metazoan kinetochores to couple the depolymerization of microtubules to power the movement of chromosomes.
酵母利用环形的Dam1复合物沿着解聚的微管下滑以移动染色体，但目前的模型表明其他真核生物没有滑动环。我们通过电子显微镜断层扫描观察了微管上的Ndc80和Ska复合物，以确定人类动粒-微管附着的结构。Ndc80招募Ska复合物，使得Ska二聚体的V形沿着原纤维相互作用。我们鉴定出一种Ndc80尾部的突变体，它在体外向动粒招募Ska以及使Ska沿着原纤维定向方面存在缺陷。这种突变的Ndc80以正常亲和力结合微管，但在沿着原纤维聚集方面存在缺陷。我们提出Ska是由Ndc80蛋白簇招募到动粒的，并且我们在微管上的Ndc80和Ska复合物结构提示了一种后生动物动粒将微管解聚与驱动染色体移动相耦合的机制。
