D-box is required for the degradation of human Shugoshin and chromosome alignment

Chromosome segregation and proper alignment in mitosis relies on cohesion between sister chromatids and the interaction of the kinetochore with spindle microtubules. Vertebrate Sgo 1 localizes to kinetochores and is required to prevent premature sister centromere separation in mitosis. Sgo 1 is degraded by the anaphase-promoting complex, allowing the separation of sister centromeres in anaphase. However, little is known about the molecular basis of Sgo 1 degradation and its temporal control during mitosis. Here, we show that APC/C targets human Sgo 1 for degradation through a destruction box motif (D-box) in its C-terminus. Mutation in the D-box causes transient metaphase arrest, and mutation in the D-box leads to defects in chromosome alignment and segregation through its effect on the localization of Aurora B and CENP-E. These results provide a link between sister centromere cohesion and bipolar attachment of kinetochores.