Wu Hsin-Yen, Burgess Sean M
Section of Molecular and Cellular Biology, Genetics Graduate Program, University of California, Davis, California, USA.
Mol Cell Biol. 2006 May;26(10):3683-94. doi: 10.1128/MCB.26.10.3683-3694.2006.
Dynamic telomere repositioning is a prominent feature of meiosis. Deletion of a telomere-associated protein, Ndj1, results in the failure of both attachment and clustering of telomeres at the nuclear envelope and delays several landmarks of meiosis I, such as pairing, synaptonemal complex formation, and timing of the meiosis I division. We explored the role of Ndj1 in meiotic recombination, which occurs through the formation and repair of programmed double-strand breaks. The ndj1delta mutation allows for the formation of the first detectable strand invasion intermediate (i.e., single-end invasion) with wild-type kinetics; however, it confers a delay in the formation of the double-Holliday junction intermediate and both crossover and noncrossover products. These results challenge the widely held notion that clustering of telomeres in meiosis promotes the ability of homologous chromosomes to find one another in budding Saccharomyces cerevisiae. We propose that an Ndj1-dependent function is critical for stabilizing analogous strand invasion intermediates that exist in two separate branches of the bifurcated pathway, leading to either noncrossover or crossover formation. These findings provide a link between telomere dynamics and a distinct mechanistic step of meiotic recombination that follows the homology search.
动态端粒重新定位是减数分裂的一个显著特征。端粒相关蛋白Ndj1的缺失会导致端粒在核膜处的附着和聚集失败,并延迟减数分裂I的几个标志性事件,如配对、联会复合体形成以及减数分裂I分裂的时间。我们探究了Ndj1在减数分裂重组中的作用,减数分裂重组是通过程序性双链断裂的形成和修复来进行的。ndj1delta突变允许以野生型动力学形成第一个可检测到的链侵入中间体(即单端侵入);然而,它会导致双Holliday连接中间体以及交叉和非交叉产物的形成延迟。这些结果挑战了一个广泛持有的观点,即在出芽酵母中,减数分裂中端粒的聚集促进了同源染色体相互找到对方的能力。我们提出,一种依赖Ndj1的功能对于稳定存在于分叉途径两个独立分支中的类似链侵入中间体至关重要,这两个分支分别导致非交叉或交叉形成。这些发现为端粒动力学与同源性搜索之后减数分裂重组的一个独特机制步骤之间提供了联系。