The interplay of RecA-related proteins and the MND1-HOP2 complex during meiosis in Arabidopsis thaliana.
The interplay of RecA-related proteins and the MND1-HOP2 complex during meiosis in Arabidopsis thaliana.
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在拟南芥中减数分裂期间，与RECA相关蛋白的相互作用和MND1-HOP2复合物的相互作用。
DOI：
10.1371/journal.pgen.0030176
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发表时间：
2007-10
期刊：
影响因子：
4.5
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中科院分区：
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在减数分裂过程中，同源染色体相互识别、对齐并交换遗传信息。这个过程需要RecA相关蛋白Rad51和Dmc1的作用来催化DNA链交换。Mnd1 - Hop2复合物已被证明有助于依赖Dmc1的过程。此外，高等真核生物拥有其他RecA相关蛋白，如XRCC3，它们参与减数分裂重组。然而，对于这些蛋白在减数分裂过程中的功能相互作用知之甚少。我们研究了拟南芥减数分裂过程中AtMND1、AtDMC1、AtRAD51和AtXRCC3之间的功能关系。我们证明了AtMND1定位于减数分裂染色体上，即使在没有重组的情况下也是如此，并且表明AtMND1的加载完全依赖于AHP2（拟南芥Hop2的同源物）。我们提供了AtMND1、AtDMC1、AtRAD51和AtXRCC3之间遗传相互作用的证据。体外实验表明，这种功能联系是由于AtMND1 - AHP2复合物与AtRAD51和AtDMC1直接相互作用。我们发现AtDMC1焦点在Atmnd1突变体中积累，但在Atrad51和Atxrcc3突变体中数量减少。这项研究首次深入了解了AtRAD51和AtXRCC3在减数分裂过程中的功能差异，表明在Atmnd1突变体背景下，AtXRCC3对于AtDMC1焦点形成是可有可无的，而AtRAD51则不是。这些结果阐明了减数分裂重组过程中链交换关键参与者之间的功能相互作用。此外，它们强调了MND1和RAD51之间的直接相互作用，并显示了RAD51和XRCC3之间的功能差异。
在减数分裂过程中，一轮染色体复制之后是两轮染色体分离，从而产生单倍体配子。正是在这种特殊的细胞分裂过程中，遗传性状通过同源染色体DNA序列的相互交换而重组。重组事件必须得到很好的控制，以确保：（i）它们发生在同源染色体之间，而不是姐妹染色单体之间；（ii）它们发生在真正的同源序列之间，而不是基因组其他位置存在的重复序列之间。在同源重组的早期步骤之一中，单链DNA分子识别并侵入目标同源序列。许多在各个生物界中都保守的蛋白质参与了DNA同源性搜索的这一关键步骤。在这项研究中，我们分析了一系列此类蛋白质在模式植物拟南芥中的作用及其复杂的功能关系，为减数分裂重组这一高度调控的步骤提供了新的见解。
During meiosis, homologous chromosomes recognize each other, align, and exchange genetic information. This process requires the action of RecA-related proteins Rad51 and Dmc1 to catalyze DNA strand exchanges. The Mnd1–Hop2 complex has been shown to assist in Dmc1-dependent processes. Furthermore, higher eukaryotes possess additional RecA-related proteins, like XRCC3, which are involved in meiotic recombination. However, little is known about the functional interplay between these proteins during meiosis. We investigated the functional relationship between AtMND1, AtDMC1, AtRAD51, and AtXRCC3 during meiosis in Arabidopsis thaliana. We demonstrate the localization of AtMND1 to meiotic chromosomes, even in the absence of recombination, and show that AtMND1 loading depends exclusively on AHP2, the Arabidopsis Hop2 homolog. We provide evidence of genetic interaction between AtMND1, AtDMC1, AtRAD51, and AtXRCC3. In vitro assays suggest that this functional link is due to direct interaction of the AtMND1–AHP2 complex with AtRAD51 and AtDMC1. We show that AtDMC1 foci accumulate in the Atmnd1 mutant, but are reduced in number in Atrad51 and Atxrcc3 mutants. This study provides the first insights into the functional differences of AtRAD51 and AtXRCC3 during meiosis, demonstrating that AtXRCC3 is dispensable for AtDMC1 focus formation in an Atmnd1 mutant background, whereas AtRAD51 is not. These results clarify the functional interactions between key players in the strand exchange processes during meiotic recombination. Furthermore, they highlight a direct interaction between MND1 and RAD51 and show a functional divergence between RAD51 and XRCC3. During meiosis, two rounds of chromosome segregation follow a single round of chromosome duplication, leading to the production of haploid gametes. It is during this specialised cell division that genetic traits are recombined, achieved by mutual exchange of DNA sequences of homologous chromosomes. Recombination events must be well controlled to ensure that: (i) they occur between homologous chromosomes rather than sister chromatids and (ii) they occur between true homologous sequences and not duplicated sequences present elsewhere in the genome. At one of the early steps of homologous recombination, a single-strand DNA molecule recognizes and invades the targeted homologous sequence. Many proteins, which are conserved throughout the kingdoms, are involved in this crucial step of DNA homology search. In this study, we analyze the role of a series of such proteins and their complex functional relationships in the model plant A. thaliana, shedding new light on this highly regulated step of meiotic recombination.