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Structure of the DASH/Dam1 complex shows its role at the yeast kinetochore-microtubule interface

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Science  04 May 2018:
Vol. 360, Issue 6388, pp. 552-558
DOI: 10.1126/science.aar6436

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Staying attached through division

When a cell prepares to divide, it copies its DNA into pairs of each chromosome, called chromatids. Microtubules attach to the chromosome pairs through protein complexes called kinetochores. During cell division, microtubule depolymerization pulls the chromatids apart. Jenni and Harrison describe the structure of an essential component of the yeast kinetochore, the DASH/Dam1c complex, that forms a ring around a microtubule. The structure shows how the DASH/Dam1c ring interacts with the microtubule and kinetochore components so that the kinetochore can track to the end of the microtubule through cycles of growth and shrinkage.

Science, this issue p. 552

Abstract

Kinetochores connect mitotic-spindle microtubules with chromosomes, allowing microtubule depolymerization to pull chromosomes apart during anaphase while resisting detachment as the microtubule shortens. The heterodecameric DASH/Dam1 complex (DASH/Dam1c), an essential component of yeast kinetochores, assembles into a microtubule-encircling ring. The ring associates with rodlike Ndc80 complexes to organize the kinetochore-microtubule interface. We report the cryo–electron microscopy structure (at ~4.5-angstrom resolution) of a DASH/Dam1c ring and a molecular model of its ordered components, validated by evolutionary direct-coupling analysis. Integrating this structure with that of the Ndc80 complex and with published interaction data yields a molecular picture of kinetochore-microtubule attachment, including how flexible, C-terminal extensions of DASH/Dam1c subunits project and contact widely separated sites on the Ndc80 complex rod and how phosphorylation at previously identified sites might regulate kinetochore assembly.

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