The accurate segregation of chromosomes during meiosis—which is critical for genome stability across sexual cycles—relies on homologous recombination initiated by DNA double-strand breaks (DSBs) made by the Spo11 protein^1,2. The formation of DSBs is regulated and tied to the elaboration of large-scale chromosome structures^3,4,5, but the protein assemblies that execute and control DNA breakage are poorly understood. Here we address this through the molecular characterization of Saccharomyces cerevisiae RMM (Rec114, Mei4 and Mer2) proteins—essential, conserved components of the DSB machinery². Each subcomplex of Rec114–Mei4 (a 2:1 heterotrimer) or Mer2 (a coiled-coil-containing homotetramer) is monodispersed in solution, but they independently condense with DNA into reversible nucleoprotein clusters that share properties with phase-separated systems. Multivalent interactions drive this condensation. Mutations that weaken protein–DNA interactions strongly disrupt both condensate formation and DSBs in vivo, and thus these processes are highly correlated. In vitro, condensates fuse into mixed RMM clusters that further recruit Spo11 complexes. Our data show how the DSB machinery self-assembles on chromosome axes to create centres of DSB activity. We propose that multilayered control of Spo11 arises from the recruitment of regulatory components and modulation of the biophysical properties of the condensates.

减数分裂过程中染色体的精确分离（这对于性周期中基因组的稳定性至关重要）依赖于由 Spo11 蛋白^1,2产生的 DNA 双链断裂 (DSB) 引发的同源重组。 DSB 的形成受到调控并与大规模染色体结构的精细化相关^3,4,5 ，但执行和控制 DNA 断裂的蛋白质组装体却知之甚少。在这里，我们通过酿酒酵母RMM（Rec114、Mei4 和 Mer2）蛋白（DSB 机制的必需、保守成分）的分子表征来解决这个问题² 。 Rec114-Mei4（2:1 异源三聚体）或 Mer2（含有卷曲螺旋的同源四聚体）的每个子复合物在溶液中单分散，但它们独立地与 DNA 缩合成可逆核蛋白簇，与相分离系统具有相同的特性。多价相互作用驱动这种凝聚。削弱蛋白质-DNA 相互作用的突变会强烈破坏体内凝聚物的形成和 DSB，因此这些过程是高度相关的。在体外，冷凝物融合成混合 RMM 簇，进一步招募 Spo11 复合物。我们的数据显示了 DSB 机器如何在染色体轴上自组装以创建 DSB 活动中心。我们认为 Spo11 的多层控制源于调节成分的招募和冷凝物生物物理特性的调节。