Abstract
Accurate chromosome segregation demands efficient capture of microtubules by kinetochores and their conversion to stable bi-oriented attachments that can congress and then segregate chromosomes. An early event is the shedding of the outermost fibrous corona layer of the kinetochore following microtubule attachment. Centromere protein F (CENP-F) is part of the corona, contains two microtubule-binding domains and physically associates with dynein motor regulators. Here, we have combined CRISPR gene editing and engineered separation-of-function mutants to define how CENP-F contributes to kinetochore function. We show here that the two microtubule-binding domains make distinct contributions to attachment stability and force generation that are required to minimise errors in anaphase, but are dispensable for congression. We further identify a specialised domain that functions to inhibit the dynein mediated stripping of CENP-E motors. We show how this “dynein-brake” is crucial for ensuring kinetochores contain the right number of CENP-E motors at the right time during mitosis, with loss of brake function delaying congression.
