减数分裂是产生配子的发育程序。为了产生健康的配子,减数分裂重组会在每对同源染色体之间产生相互交换,从而促进忠实的染色体分离。利用裂变酵母和生化,遗传,和细胞学方法,我们研究了CDK(细胞周期蛋白依赖性激酶)在Swi5-Sfr1控制中的作用,Swi5-Sfr1是一种Rad51重组酶辅助因子,参与重组过程中同源物的侵袭。我们证明Sfr1是CDK目标,其磷酸化在减数分裂前期下调Swi5-Sfr1功能。磷酸化模拟sfr1-7D突变体的表达抑制Rad51结合,它强大的染色体负载,并随后减少同源物之间的重组。另一方面,非磷酸化sfr1-7A突变体在后期改变Rad51动力学,并加剧了在dbl2缺失突变体中观察到的染色质分离缺陷和Rad51保留。我们提出Sfr1磷酸抑制作为一种新的细胞周期依赖性机制,这确保了重组中间体的及时解决和成功的染色体分配到配子中。此外,Sfr1的N端无序部分,一个进化保守的特征,作为协调这种磷酸调节的监管平台,蛋白质定位和稳定性,几个CDK位点和调控序列是保守的。
Meiosis is the developmental program that generates gametes. To produce healthy gametes, meiotic
recombination creates reciprocal exchanges between each pair of homologous chromosomes that facilitate faithful chromosome segregation. Using fission yeast and biochemical, genetic, and cytological approaches, we have studied the role of CDK (cyclin-dependent kinase) in the control of Swi5-Sfr1, a Rad51-recombinase auxiliary factor involved in homolog invasion during
recombination. We show that Sfr1 is a CDK target, and its phosphorylation downregulates Swi5-Sfr1 function in the meiotic prophase. Expression of a phospho-mimetic sfr1-7D mutant inhibits Rad51 binding, its robust chromosome loading, and subsequently decreases interhomolog
recombination. On the other hand, the non-phosphorylatable sfr1-7A mutant alters Rad51 dynamics at late prophase, and exacerbates chromatin segregation defects and Rad51 retention observed in dbl2 deletion mutants when combined with them. We propose Sfr1 phospho-inhibition as a novel cell-cycle-dependent mechanism, which ensures timely resolution of
recombination intermediates and successful chromosome distribution into the gametes. Furthermore, the N-terminal disordered part of Sfr1, an evolutionarily conserved feature, serves as a regulatory platform coordinating this phospho-regulation, protein localization and stability, with several CDK sites and regulatory sequences being conserved.