Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA.
J Cell Biol. 2011 Aug 22;194(4):539-49. doi: 10.1083/jcb.201103044. Epub 2011 Aug 15.
Aurora B kinase is essential for successful cell division and regulates spindle assembly and kinetochore-microtubule interactions. The kinase localizes to the inner centromere until anaphase, but many of its substrates have distinct localizations, for example on chromosome arms and at kinetochores. Furthermore, substrate phosphorylation depends on distance from the kinase. How the kinase reaches substrates at a distance and how spatial phosphorylation patterns are determined are unknown. In this paper, we show that a phosphorylation gradient is produced by Aurora B concentration and activation at centromeres and release and diffusion to reach substrates at a distance. Kinase concentration, either at centromeres or at another chromosomal site, is necessary for activity globally. By experimentally manipulating dynamic exchange at centromeres, we demonstrate that the kinase reaches its substrates by diffusion. We also directly observe, using a fluorescence resonance energy transfer-based biosensor, phosphorylation spreading from centromeres after kinase activation. We propose that Aurora B dynamics and diffusion from the inner centromere create spatial information to regulate cell division.
极光 B 激酶对于成功的细胞分裂是必不可少的，它调节纺锤体的组装和动粒微管的相互作用。该激酶定位于着丝粒内部，直到后期，但它的许多底物具有不同的定位，例如在染色体臂上和动粒上。此外，底物磷酸化依赖于与激酶的距离。激酶如何到达远处的底物，以及如何确定空间磷酸化模式尚不清楚。在本文中，我们表明，由着丝粒处的 Aurora B 浓度和激活产生磷酸化梯度，并通过释放和扩散到达远处的底物。激酶浓度，无论是在着丝粒处还是在另一个染色体位点，对于全局活性都是必要的。通过实验性地操纵着丝粒处的动态交换，我们证明激酶通过扩散到达其底物。我们还使用基于荧光共振能量转移的生物传感器直接观察到激酶激活后从着丝粒开始的磷酸化扩散。我们提出，极光 B 的动力学和从内部着丝粒的扩散为调节细胞分裂创造了空间信息。
