The RTR Complex Partner RMI2 and the DNA Helicase RTEL1 Are Both Independently Involved in Preserving the Stability of 45S rDNA Repeats in Arabidopsis thaliana.
The RTR Complex Partner RMI2 and the DNA Helicase RTEL1 Are Both Independently Involved in Preserving the Stability of 45S rDNA Repeats in Arabidopsis thaliana.
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DOI：
10.1371/journal.pgen.1006394
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发表时间：
2016-10
期刊：
影响因子：
4.5
通讯作者：
Puchta H
中科院分区：
文献类型：
--
作者：
Röhrig S;Schröpfer S;Knoll A;Puchta H
复杂真核基因组中重复序列的稳定性通过抑制同源重组的因素来保障。其中最突出的是 RTR 复合体的作用。在植物中，它由 RecQ 解旋酶 RECQ4A、拓扑异构酶 TOP3α 和 RMI1 组成。与哺乳动物（但与酵母不同）一样，植物还拥有一个额外的复杂伙伴：RMI2。在这里，我们证明，在拟南芥中，RMI2 参与根分生组织中异常复制中间体的修复以及链内交联修复。在这两种情况下，RMI2 都独立于 DNA 解旋酶 RTEL1 参与。令人惊讶的是，RMI2 和 RTEL1 同时丢失会导致男性生育能力丧失。由于RTR复合物和RTEL1都参与同源重组（HR）的抑制，我们测试了双突变体rmi2-2 rtel1-1中HR的效率，发现协同增强（80倍）。在寻找天然靶序列时，我们发现 RTEL1 是稳定 45S rDNA 重复序列所必需的。在带有 rmi2-2 的双突变体中，45S rDNA 重复的数量进一步减少，维持了两个因子在此过程中的独立作用。因此，HR 抑制的丧失不仅会导致 rDNA 重复序列的不稳定，而且可能对经历多次细胞分裂的组织（例如雄性种系）特别有害。布卢姆综合征和霍耶拉尔·赫里达森综合征是与基因组不稳定相关的严重人类疾病。有趣的是，植物含有在相应疾病中存在缺陷的因子的同源物。在模式植物拟南芥中，这些蛋白质在遗传信息修复和重复元件维持的各个方面发挥着重要作用。在这里，我们发现，代表每种综合症的两个特定因子的功能同时丧失，会导致植物雄性不育，这是由于体细胞灾难导致不稳定和细胞死亡。这种缺陷与参与一般蛋白质生产的重复基因的大量丢失有关。之前已经证明，对于哺乳动物来说，失去某些与基因组稳定性有关的其他因素会导致神经发育缺陷。我们的结果现在表明，基因组不稳定性也会导致植物中器官特异性缺陷，在我们的例子中，在花发育过程中，导致减数分裂前雄性种系的细胞增殖缺陷。
The stability of repetitive sequences in complex eukaryotic genomes is safeguarded by factors suppressing homologues recombination. Prominent in this is the role of the RTR complex. In plants, it consists of the RecQ helicase RECQ4A, the topoisomerase TOP3α and RMI1. Like mammals, but not yeast, plants harbor an additional complex partner, RMI2. Here, we demonstrate that, in Arabidopsis thaliana, RMI2 is involved in the repair of aberrant replication intermediates in root meristems as well as in intrastrand crosslink repair. In both instances, RMI2 is involved independently of the DNA helicase RTEL1. Surprisingly, simultaneous loss of RMI2 and RTEL1 leads to loss of male fertility. As both the RTR complex and RTEL1 are involved in suppression of homologous recombination (HR), we tested the efficiency of HR in the double mutant rmi2-2 rtel1-1 and found a synergistic enhancement (80-fold). Searching for natural target sequences we found that RTEL1 is required for stabilizing 45S rDNA repeats. In the double mutant with rmi2-2 the number of 45S rDNA repeats is further decreased sustaining independent roles of both factors in this process. Thus, loss of suppression of HR does not only lead to a destabilization of rDNA repeats but might be especially deleterious for tissues undergoing multiple cell divisions such as the male germline. The Bloom syndrome and Hoyeraal Hreidarsson syndrome are severe diseases in humans that are correlated with genome instability. Interestingly, plants harbor homologs of factors that are defective in the respective diseases. In the model plant A. thaliana these proteins play important roles in various aspects of the repair of genetic information and the maintenance of repetitive elements. Here, we show that the concomitant loss of function of two specific factors that are representative for each syndrome leads in plants to male sterility, due to somatic catastrophe leading to instability and cell death. This defect is correlated with a massive loss of repetitive genes involved in general protein production. It has been shown before for mammals that loss of certain other factors involved in genome stability leads to a defect in neural development. Our results now demonstrate that genome instability can also result in organ-specific defects in plants, in our case during flower development, leading to a defect in the cell proliferation of the premeiotic male germline.
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影响因子：
4.5
作者：
Chelysheva L;Vezon D;Belcram K;Gendrot G;Grelon M
通讯作者：
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DOI：
10.1007/978-1-60761-103-5_9
发表时间：
2009-01-01
期刊：
MEIOSIS, VOL 2: CYTOLOGICAL METHODS
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