Feng Zhe, Caballe Anna, Wainman Alan, Johnson Steven, Haensele Andreas F M, Cottee Matthew A, Conduit Paul T, Lea Susan M, Raff Jordan W
The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
The Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
Cell. 2017 Jun 1;169(6):1078-1089.e13. doi: 10.1016/j.cell.2017.05.030.
In flies, Centrosomin (Cnn) forms a phosphorylation-dependent scaffold that recruits proteins to the mitotic centrosome, but how Cnn assembles into a scaffold is unclear. We show that scaffold assembly requires conserved leucine zipper (LZ) and Cnn-motif 2 (CM2) domains that co-assemble into a 2:2 complex in vitro. We solve the crystal structure of the LZ:CM2 complex, revealing that both proteins form helical dimers that assemble into an unusual tetramer. A slightly longer version of the LZ can form micron-scale structures with CM2, whose assembly is stimulated by Plk1 phosphorylation in vitro. Mutating individual residues that perturb LZ:CM2 tetramer assembly perturbs the formation of these micron-scale assemblies in vitro and Cnn-scaffold assembly in vivo. Thus, Cnn molecules have an intrinsic ability to form large, LZ:CM2-interaction-dependent assemblies that are critical for mitotic centrosome assembly. These studies provide the first atomic insight into a molecular interaction required for mitotic centrosome assembly.
在果蝇中，中心体蛋白（Cnn）形成一种依赖磷酸化的支架，将蛋白质招募到有丝分裂中心体，但Cnn如何组装成支架尚不清楚。我们发现，支架组装需要保守的亮氨酸拉链（LZ）和Cnn基序2（CM2）结构域，它们在体外共同组装成2:2复合物。我们解析了LZ:CM2复合物的晶体结构，发现这两种蛋白质都形成螺旋二聚体，进而组装成一个不同寻常的四聚体。LZ的一个稍长版本可以与CM2形成微米级结构，其组装在体外受到Plk1磷酸化的刺激。突变扰乱LZ:CM2四聚体组装的单个残基会扰乱这些微米级组装在体外的形成以及体内Cnn支架的组装。因此，Cnn分子具有形成大型、依赖LZ:CM2相互作用的组装体的内在能力，这对有丝分裂中心体组装至关重要。这些研究首次从原子层面深入了解了有丝分裂中心体组装所需的分子相互作用。
