Chromosome Segregation Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
Curr Biol. 2012 Dec 4;22(23):R1012-21. doi: 10.1016/j.cub.2012.10.023.
The processes underlying the large-scale reorganisation of chromatin in mitosis that form compact mitotic chromosomes and ensure the fidelity of chromosome segregation during cell division still remain obscure. The chromosomal condensin complex is a major molecular effector of chromosome condensation and segregation in diverse organisms ranging from bacteria to humans. Condensin is a large, evolutionarily conserved, multisubunit protein assembly composed of dimers of the structural maintenance of chromosomes (SMC) family of ATPases, clasped into topologically closed rings by accessory subunits. Condensin binds to DNA dynamically, in a poorly understood cycle of ATP-modulated conformational changes, and exhibits the ability to positively supercoil DNA. During mitosis, condensin is phosphorylated by the cyclin-dependent kinase (CDK), Polo and Aurora B kinases in a manner that correlates with changes in its localisation, dynamics and supercoiling activity. Here we review the reported architecture, biochemical activities and regulators of condensin. We compare models of bacterial and eukaryotic condensins in order to uncover conserved mechanistic principles of condensin action and to propose a model for mitotic chromosome condensation.
有丝分裂中染色质大规模重组的背后机制形成了紧凑的有丝分裂染色体，并确保了细胞分裂过程中染色体分离的保真度，但这些机制仍不清楚。染色体凝聚素复合物是一种主要的分子效应物，可在从细菌到人类等各种生物中促进染色体的凝聚和分离。凝聚素是一种由结构维持染色体（SMC）家族 ATP 酶的二聚体组成的大型、进化上保守的多亚基蛋白组装体，通过辅助亚基形成拓扑闭合环。凝聚素通过一个未知的 ATP 调节构象变化循环与 DNA 动态结合，并表现出能够正向超螺旋化 DNA 的能力。在有丝分裂过程中，凝聚素被细胞周期蛋白依赖性激酶（CDK）、Polo 和 Aurora B 激酶磷酸化，这种磷酸化与它的定位、动力学和超螺旋化活性的变化相关。在这里，我们回顾了报道的凝聚素的结构、生化活性和调节剂。我们比较了细菌和真核凝聚素的模型，以揭示凝聚素作用的保守机制原则，并提出一个有丝分裂染色体凝聚的模型。
