Mechanism of Ska Recruitment by Ndc80 Complexes to Kinetochores

Publication date: 22 May 2017
Source:Developmental Cell, Volume 41, Issue 4
Author(s): Paweł Ł. Janczyk, Katarzyna A. Skorupka, John G. Tooley, Daniel R. Matson, Cortney A. Kestner, Thomas West, Owen Pornillos, P. Todd Stukenberg
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.

Teaser

The Ska complex matures kinetochore-microtubule attachments, but it is unclear how kinetochores recruit Ska. Janczyk et al. show that Ndc80 complex on microtubules can directly recruit the Ska complex and orient it along microtubules. Mutants of the Ndc80 tail that cannot cluster along microtubules do not recruit Ska to kinetochores.


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