Kinetochore orientation during meiosis is controlled by Aurora B and the monopolin complex

Kinetochores of sister chromatids attach to microtubules emanating from the same pole (coorientation) during meiosis I and microtubules emanating from opposite poles (biorientation) during meiosis II. We find that the Aurora B kinase Ipl1 regulates kinetochore-microtubule attachment during both meiotic divisions and that a complex known as the monopolin complex ensures that the protein kinase coorients sister chromatids during meiosis I. Furthermore, the defining of conditions sufficient to induce sister kinetochore coorientation during mitosis provides insight into monopolin complex function. The monopolin complex joins sister kinetochores independently of cohesins, the proteins that hold sister chromatids together. We propose that this function of the monopolin complex helps Aurora B coorient sister chromatids during meiosis I.