Phosphorylation of HsMis13 by Aurora B Kinase Is Essential

Chromosome movements in mitosis are orchestrated by dynamic interactions between spindle microtubules and the kinetochore, a multiprotein complex assembled onto centro-meric DNA of the chromosome. Here we show that phosphoryl-ation of human HsMis13 by Aurora B kinase is required for functional kinetochore assembly in HeLa cells. Aurora B inter-acts with HsMis13 in vitro and in vivo. HsMis13 is a cognate substrate of Aurora B, and the phosphorylation sites were mapped to Ser-100 and Ser-109. Suppression ofAuroraB kinase by either small interfering RNA or chemical inhibitors abro-gates the localization of HsMis13 but not HsMis12 to the kine-tochore. In addition, non-phosphorylatable but not wild type and phospho-mimicking HsMis13 failed to localize to the kine-tochore, demonstrating the requirement of phosphorylation by Aurora B for the assembly of HsMis13 to kinetochore. In fact