A 3D Map of the Yeast Kinetochore Reveals the Presence of Core and Accessory Centromere-Specific Histone

The budding yeast kinetochore is ~68nm in length with a diameter slightly larger than a 25nm microtubule [1]. The kinetochores from the 16 chromosomes are organized in a stereotypic cluster encircling central spindle microtubules. Quantitative analysis of the inner kinetochore cluster (Cse4, COMA) reveals structural features not apparent in singly attached kinetochores. The cluster of Cse4 containing kinetochores is physically larger perpendicular to the spindle axis relative to the cluster of Ndc80 molecules [2]. If there were a single Cse4 (molecule or nucleosome) at the kinetochore attached to each microtubule plus-end, the cluster of Cse4 would appear geometrically identical to Ndc80. Thus, the structure of the inner kinetochore at the surface of the chromosomes remains unsolved