The greatest kinetochore show on earth

Abstract

Coordinated chromosome duplication and segregation is key to the existence of every organism on our planet. In eukaryotes, sophisticated protein assemblies called kinetochores are universally required for chromosome segregation, but their protein composition can diverge across the eukaryotic tree of life. In this issue of EMBO Reports, van Hooff et al [1] shed light on kinetochore evolution with a comprehensive study of kinetochore composition across 90 phylogenetically diverse eukaryotes. They show that certain kinetochore complexes have taken distinct evolutionary paths to arrive at a strikingly broad compositional array in present‐day eukaryotes, providing exciting new insights into the origins, function, and flexibility of eukaryotic kinetochores.See also: JJE van Hooff et al (September 2017)Kinetochores are the workhorses of chromosome segregation, and all eukaryotes likely depend on dynamic kinetochore–microtubule interactions to guide the assortment of chromosomes into daughter cells [2]. To achieve their feat, kinetochores assemble onto specific chromosomal regions, termed centromeres, which, in most cases, function independently of the underlying DNA sequence. Feedback mechanisms, known as the spindle assembly checkpoint (SAC) and the error‐correction network, are integral parts of the kinetochore, and safeguard chromosome assortment. The functional specialization of kinetochores is reflected in distinct structural modules responsible, respectively, for the assembly onto centromeres (the inner kinetochore) and the interaction with microtubules (the outer kinetochore). SAC and error‐correction signaling components interact with the outer kinetochore, where they “read” microtubule attachment status. Physical interactions linking the ~70 subunits in the different kinetochore modules have been partly elucidated in different model organisms [2].Despite an apparently universal function, there is evidence of considerable evolutionary diversification of kinetochore structure (Fig 1A). For instance, the kinetochores of the budding yeast S. …