Centromeric chromatin in mitosis reorganizes into a functional structure stabilized by cohesin [NG-Capture-C]
Three-dimensional organization of mitotic chromosomes is established by cohesin and condensin complexes. In the centromere, cohesin maintains sister chromatid pairing until anaphase onset, while condensin provides elastic resistance to spindle forces. However, how condensin and cohesin structure vertebrate centromeres remains unclear. By super-resolution imaging, Capture-C analysis and polymer modeling we show that vertebrate centromeres are partitioned into two condensin-dependent subdomains during mitosis. This bipartite sub-structure is found in human, mouse and chicken centromeres, and is therefore a fundamental feature of vertebrate centromere. Super-resolution imaging and electron tomography reveal that bipartite centromeres assemble bipartite kinetochores with each subdomain capable of binding a distinct microtubule bundle. Cohesin helps to link the centromere subdomains, limiting their separation in response to spindle forces and preventing merotelic attachments. The two-domain structure described here may have implications for avoiding chromosomal instability as uncoupling of centromere subdomains is a common feature of lagging chromosomes in cancer cells. Overall design: NG-Capture-C analysis to inveistigate chromatin organisation of non-repetitive centromres such as Z and 5 in chicken DT40 CDK1as cells at G2 and prometaphase.