Archambault Vincent, D'Avino Pier Paolo, Deery Michael J, Lilley Kathryn S, Glover David M
Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, United Kingdom.
Genes Dev. 2008 Oct 1;22(19):2707-20. doi: 10.1101/gad.486808.
The conserved Polo kinase controls multiple events in mitosis and cytokinesis. Although Polo-like kinases are regulated by phosphorylation and proteolysis, control of subcellular localization plays a major role in coordinating their mitotic functions. This is achieved largely by the Polo-Box Domain, which binds prephosphorylated targets. However, it remains unclear whether and how Polo might interact with partner proteins when priming mitotic kinases are inactive. Here we show that Polo associates with microtubules in interphase and cytokinesis, through a strong interaction with the microtubule-associated protein Map205. Surprisingly, this interaction does not require priming phosphorylation of Map205, and the Polo-Box Domain of Polo is required but not sufficient for this interaction. Moreover, phosphorylation of Map205 at a CDK site relieves this interaction. Map205 can stabilize Polo and inhibit its cellular activity in vivo. In syncytial embryos, the centrosome defects observed in polo hypomorphs are enhanced by overexpression of Map205 and suppressed by its deletion. We propose that Map205-dependent targeting of Polo to microtubules provides a stable reservoir of Polo that can be rapidly mobilized by the activity of Cdk1 at mitotic entry.
保守的Polo激酶控制有丝分裂和胞质分裂中的多个事件。尽管Polo样激酶受磷酸化和蛋白水解调节，但亚细胞定位的控制在协调其有丝分裂功能中起主要作用。这主要通过与预磷酸化靶标结合的Polo盒结构域来实现。然而，当引发有丝分裂激酶失活时，Polo是否以及如何与伴侣蛋白相互作用仍不清楚。在这里，我们表明Polo在间期和胞质分裂中与微管相关，通过与微管相关蛋白Map205的强烈相互作用。令人惊讶的是，这种相互作用不需要Map205的引发磷酸化，并且Polo的Polo盒结构域是必需的，但不足以实现这种相互作用。此外，Map205在CDK位点的磷酸化可减轻这种相互作用。Map205可以在体内稳定Polo并抑制其细胞活性。在合胞体胚胎中，过表达Map205会增强polo低表达体中观察到的中心体缺陷，而缺失Map205则会抑制这种缺陷。我们提出，Map205依赖的Polo靶向微管提供了一个稳定的Polo库，在有丝分裂进入时可以被Cdk1的活性迅速动员。
