MRC Genome Damage and Stability Centre, University of Sussex, Brighton, United Kingdom.
PLoS One. 2012;7(6):e39724. doi: 10.1371/journal.pone.0039724. Epub 2012 Jun 22.
Budding yeast Pch2 protein is a widely conserved meiosis-specific protein whose role is implicated in the control of formation and displacement of meiotic crossover events. In contrast to previous studies where the function of Pch2 was implicated in the steps after meiotic double-strand breaks (DSBs) are formed, we present evidence that Pch2 is involved in meiotic DSB formation, the initiation step of meiotic recombination. The reduction of DSB formation caused by the pch2 mutation is most prominent in the sae2 mutant background, whereas the impact remains mild in the rad51 dmc1 double mutant background. The DSB reduction is further pronounced when pch2 is combined with a hypomorphic allele of SPO11. Interestingly, the level of DSB reduction is highly variable between chromosomes, with minimal impact on small chromosomes VI and III. We propose a model in which Pch2 ensures efficient formation of meiotic DSBs which is necessary for igniting the subsequent meiotic checkpoint responses that lead to proper differentiation of meiotic recombinants.
芽殖酵母 Pch2 蛋白是一种广泛保守的减数分裂特异性蛋白，其作用涉及调控减数分裂交叉事件的形成和移位。与之前的研究不同，之前的研究表明 Pch2 的功能涉及到减数分裂双链断裂（DSB）形成后的步骤，我们提供的证据表明 Pch2 参与减数分裂 DSB 的形成，这是减数分裂重组的起始步骤。pch2 突变引起的 DSB 形成减少在 sae2 突变体背景中最为明显，而在 rad51 dmc1 双突变体背景中影响仍然较轻。当 pch2 与 SPO11 的功能降低等位基因结合时，DSB 减少更为明显。有趣的是，DSB 减少的程度在染色体之间差异很大，对小染色体 VI 和 III 的影响最小。我们提出了一个模型，其中 Pch2 确保了减数分裂 DSB 的有效形成，这对于引发随后的减数分裂检查点反应，从而导致减数分裂重组体的适当分化是必要的。
