Liu Kaixian, Grasso Emily M, Pu Stephen, Liu Shixin, Eliezer David, Keeney Scott
Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, USA.
Department of Biochemistry and Program in Structural Biology, Weill Cornell Medicine, New York, NY, USA.
bioRxiv. 2023 Jan 18:2023.01.18.524603. doi: 10.1101/2023.01.18.524603.
The DNA double-strand breaks (DSBs) that initiate meiotic recombination are formed by an evolutionarily conserved suite of factors that includes Rec114 and Mei4 (RM), which regulate DSB formation both spatially and temporally. , these proteins form large immunostaining foci that are integrated with higher order chromosome structures. , they form a 2:1 heterotrimeric complex that binds cooperatively to DNA to form large, dynamic condensates. However, understanding of the atomic structures and dynamic DNA binding properties of RM complexes is lacking. Here, we report a structural model of a heterotrimeric complex of the C-terminus of Rec114 with the N-terminus of Mei4, supported by nuclear magnetic resonance experiments. This minimal complex, which lacks the predicted intrinsically disordered region of Rec114, is sufficient to bind DNA and form condensates. Single-molecule experiments reveal that the minimal complex can bridge two or more DNA duplexes and can generate force to condense DNA through long-range interactions. AlphaFold2 predicts similar structural models for RM orthologs across diverse taxa despite their low degree of sequence similarity. These findings provide insight into the conserved networks of protein-protein and protein-DNA interactions that enable condensate formation and promote formation of meiotic DSBs.
引发减数分裂重组的DNA双链断裂（DSB）由一组进化上保守的因子形成，其中包括Rec114和Mei4（RM），它们在空间和时间上调节DSB的形成。这些蛋白质形成与高阶染色体结构整合的大型免疫染色焦点。它们形成一种2:1的异源三聚体复合物，该复合物与DNA协同结合以形成大型动态凝聚物。然而，目前缺乏对RM复合物的原子结构和动态DNA结合特性的了解。在这里，我们报告了一个由Rec114的C末端与Mei4的N末端组成的异源三聚体复合物的结构模型，该模型得到了核磁共振实验的支持。这个最小的复合物缺乏Rec114预测的内在无序区域，但足以结合DNA并形成凝聚物。单分子实验表明，最小的复合物可以桥接两个或更多的DNA双链体，并可以通过长程相互作用产生凝聚DNA的力。尽管不同分类群中的RM直系同源物序列相似性较低，但AlphaFold2预测了相似的结构模型。这些发现为蛋白质-蛋白质和蛋白质-DNA相互作用的保守网络提供了见解，这些相互作用能够形成凝聚物并促进减数分裂DSB的形成。
