Saxena Sandeep, Yuan Ping, Dhar Suman Kumar, Senga Takeshi, Takeda David, Robinson Howard, Kornbluth Sally, Swaminathan Kunchithapadam, Dutta Anindya
Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville 22908, USA.
Mol Cell. 2004 Jul 23;15(2):245-58. doi: 10.1016/j.molcel.2004.06.045.
Geminin is a cellular protein that associates with Cdt1 and inhibits Mcm2-7 loading during S phase. It prevents multiple cycles of replication per cell cycle and prevents episome replication. It also directly inhibits the HoxA11 transcription factor. Here we report that geminin forms a parallel coiled-coil homodimer with atypical residues in the dimer interface. Point mutations that disrupt the dimerization abolish interaction with Cdt1 and inhibition of replication. An array of glutamic acid residues on the coiled-coil domain surface interacts with positive charges in the middle of Cdt1. An adjoining region interacts independently with the N-terminal 100 residues of Cdt1. Both interactions are essential for replication inhibition. The negative residues on the coiled-coil domain and a different part of geminin are also required for interaction with HoxA11. Therefore a rigid cylinder with negative surface charges is a critical component of a bipartite interaction interface between geminin and its cellular targets.
Geminin是一种细胞蛋白，在S期与Cdt1结合并抑制Mcm2 - 7的装载。它可防止每个细胞周期进行多次复制循环，并阻止附加体复制。它还直接抑制HoxA11转录因子。在此我们报告，Geminin在二聚体界面形成具有非典型残基的平行卷曲螺旋同型二聚体。破坏二聚化的点突变会消除与Cdt1的相互作用并抑制复制。卷曲螺旋结构域表面的一系列谷氨酸残基与Cdt1中部的正电荷相互作用。一个相邻区域独立地与Cdt1的N端100个残基相互作用。这两种相互作用对于复制抑制都是必不可少的。卷曲螺旋结构域上的负性残基以及Geminin的不同部分对于与HoxA11的相互作用也是必需的。因此，具有负表面电荷的刚性圆柱体是Geminin与其细胞靶点之间二分相互作用界面的关键组成部分。
