Tethering NDC80-NUF2 to microparticles is sufficient to enable their biorientation in the spindle

Faithful chromosome segregation requires biorientation, where the pair of kinetochores on the chromosome establish bipolar microtubule attachment. The integrity of the kinetochore, a macromolecular complex built on centromeric DNA, is required for biorientation, but components sufficient for biorientation remain unknown. In this study, we show that tethering the outer kinetochore heterodimer NDC80-NUF2 to the surface of microbeads with no bipolar cue is sufficient for them to establish a biorientation-like state in mouse oocytes. NDC80-NUF2 microbeads efficiently and stably align at the spindle equator, forming bipolar microtubule attachments. Furthermore, they can self-correct alignment errors. They align independently of the outer kinetochore proteins SPC24-SPC25, KNL1, the MIS12 complex, or inner kinetochore proteins. Aurora-mediated NDC80 phosphoregulation promoted microbead alignment under challenging conditions. Interestingly, larger microbeads align more rapidly, suggesting that large platform size enhances NDC80-NUF2-mediated biorientation. This study shows a biohybrid kinetochore design for synthetic biorientation of microscale particles in cells.