Jcb_201408081 1..11

The cell division cycle is regulated by reversible protein phosphorylation that is spatiotemporally coordinated. The conserved Polo kinase is essential for several events of mitosis and cytokinesis (Archambault and Glover, 2009; Zitouni et al., 2014). Pololike kinase (Plk) family members are defined by an N-terminal kinase domain (KD) and a C-terminal Polo-Box domain (PBD), which mediates protein interactions (Lowery et al., 2005; Park et al., 2010). In humans, Plk1 is the closest orthologue of Drosophila melanogaster Polo in its essential roles in cell division (Petronczki et al., 2008). The complex functions of Plks are enabled by several regulatory mechanisms (Archambault and Glover, 2009; Zitouni et al., 2014). The PBD allows Polo to interact with substrates and adaptor proteins that recruit Polo to discrete locations in the cell including centrosomes, centromeres, and the midbody (Archambault and Glover, 2009; Park et al., 2010). The PBD is a phospho-binding module, and many of its interactions are facilitated by prior phosphorylation of the partner (Elia et al., 2003a,b; Park et al., 2010). However, some PBD-dependent partners of Plks do not require phospho-priming. This is the case for Map205, a microtubule-associated protein that binds and stabilizes Polo. Instead of promoting formation of the complex, phosphorylation of Map205 at a Cdk site in early mitosis negatively regulates its interaction with Polo (Archambault et al., 2008). Like several kinases, Plks are activated by phosphorylation in their T-loop (Qian et al., 1999; Archambault and Carmena, 2012). In humans, this phosphorylation of Plk1 occurs at Thr210 and is mediated by Aurora A kinase, with its cofactor Bora in G2 (Jang et al., 2002b; Macůrek et al., 2008; Seki et al., 2008b). Although Bora is degraded in mitosis, persisting low levels of Aurora A–Bora maintain Plk1 activity until anaphase (Chan et al., 2008; Seki et al., 2008a; Bruinsma et al., 2014). In Drosophila, we have shown that Aurora B kinase, a member of the chromosomal passenger complex (CPC), is required for T-loop phosphorylation of Polo at centromeres in early mitosis (Carmena et al., 2012a,b). Failure of the CPC to activate Polo in prometaphase leads to chromosome alignment and segregation defects (Carmena et al., 2012a). The function of a Plk is required for cytokinesis from yeasts to humans (Petronczki et al., 2008; Archambault and Glover, 2009). In human cells, Plk1 is targeted to the central spindle via its interaction with PRC1 (Neef et al., 2007). Similarly, D rosophila melanogaster Polo and its human orthologue Polo-like kinase 1 fulfill essential roles during cell division. Members of the Polo-like kinase (Plk) family contain an N-terminal kinase domain (KD) and a C-terminal Polo-Box domain (PBD), which mediates protein interactions. How Plks are regulated in cytokinesis is poorly understood. Here we show that phosphorylation of Polo by Aurora B is required for cytokinesis. This phosphorylation in the activation loop of the KD promotes the dissociation of Polo from the PBD-bound microtubule-associated protein Map205, which acts as an allosteric inhibitor of Polo kinase activity. This mechanism allows the release of active Polo from microtubules of the central spindle and its recruitment to the site of cytokinesis. Failure in Polo phosphorylation results in both early and late cytokinesis defects. Importantly, the antagonistic regulation of Polo by Aurora B and Map205 in cytokinesis reveals that interdomain allosteric mechanisms can play important roles in controlling the cellular functions of Plks. Interdomain allosteric regulation of Polo kinase by Aurora B and Map205 is required for cytokinesis