Mer2 ChIP-seq

To segregate accurately during meiosis, homologous chromosomes in most species must recombine. Very small chromosomes would risk missegregation if recombination were randomly distributed, so the double-strand breaks (DSBs) that initiate recombination are not haphazard. How this nonrandomness is controlled is not understood. Here we demonstrate that Saccharomyces cerevisiae integrates multiple, temporally distinct pathways to regulate chromosomal binding of pro-DSB factors Rec114 and Mer2, thereby controlling duration of a DSB-competent state. Homologous chromosome engagement regulates Rec114/Mer2 dissociation late in prophase, whereas replication timing and proximity to centromeres or telomeres influence timing and amount of Rec114/Mer2 accumulation early. A distinct early mechanism boosts Rec114/Mer2 binding quickly to high levels specifically on the shortest chromosomes, dependent on chromosome axis proteins and subject to selection pressure to maintain hyperrecombinogenic properties of these chromosomes. Thus, an organism’s karyotype and its attendant risk of meiotic missegregation influence the shape and evolution of its recombination landscape. Twenty-four samples total: 12 time points (each time points contains ChIP and input samples) from Mer2-myc ars∆ strain为确保减数分裂过程中同源染色体精准分离，多数物种的同源染色体必须发生重组。若重组随机分布，微小染色体将面临染色体分离错误的风险，因此启动重组的双链断裂（double-strand breaks, DSBs）并非随机发生。目前，这种重组非随机分布的调控机制仍未明确。本研究证实，酿酒酵母（Saccharomyces cerevisiae）通过整合多条时序各异的通路，调控促DSB形成因子Rec114与Mer2的染色体结合活性，进而控制DSB感受态状态的持续时长。同源染色体的结合可调控减数分裂前期晚期Rec114/Mer2的解离过程，而复制时序、着丝粒或端粒的邻近区域则会影响早期Rec114/Mer2的积累时序与丰度。另有一条独立的早期调控通路，可特异性地在最短染色体上快速将Rec114/Mer2的结合水平提升至峰值，该过程依赖于染色体轴蛋白，并受到维持这些染色体高重组特性的选择压力作用。由此可见，生物体的核型及其伴随的减数分裂分离错误风险，会影响其重组图谱的形态与进化历程。本数据集共计24个样本：来自Mer2-myc ars缺失菌株的12个时间点样本（每个时间点均包含染色质免疫沉淀（ChIP）与输入对照样本）。