CHROMOSOME STABILITY · Molecular mechanism of separase dependent PP2ACdc55 downregulation

Activation of the protease separase at anaphase onset leads to cleavage of cohesin, thereby triggering chromosome segragation. At the same time, an essential protease-independent function of separase promotes cell cycle progression out of mitosis. In the host laboratory it has been recently shown that separase interacts with the Cdc55 isoform of protein phosphatase 2A (PP2ACdc55) at anaphase onset, downregulating it (Queralt et al. 2006). However, the molecular nature of this non-proteolytic activity of separase and how it mediates PP2ACdc55 downregulation is still unknown. In this research project we propose to address the molecular mechanism by which separase downregulates PP2ACdc55 at anaphase onset.