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. In vivo, these proteins form large immunostaining foci that are integrated with higher-order chromosome structures. In vitro, 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.

中文翻译：

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Rec114-Mei4 三聚体必需界面的结构和 DNA 桥接活性

启动减数分裂重组的 DNA 双链断裂 (DSB) 由一系列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。在体内，这些蛋白质形成与高级染色体结构整合的大型免疫染色灶。在体外，它们形成 2:1 异源三聚体复合物，与 DNA 协同结合形成大的动态凝聚物。然而，人们对 RM 复合物的原子结构和动态 DNA 结合特性的了解还很缺乏。在这里，我们报告了 Rec114 C 末端与 Mei4​​ N 末端的异三聚体复合物的结构模型，并得到核磁共振实验的支持。这种最小的复合物缺乏预计的 Rec114 本质上无序的区域，足以结合 DNA 并形成缩合物。单分子实验表明，最小复合物可以桥接两个或多个 DNA 双链体，并可以通过长程相互作用产生凝聚 DNA 的力。AlphaFold2 预测不同类群中 RM 直向同源物的相似结构模型，尽管它们的序列相似度较低。这些发现提供了对蛋白质-蛋白质和蛋白质-DNA 相互作用的保守网络的深入了解，这些网络能够形成凝聚体并促进减数分裂 DSB 的形成。