Fission Yeast RecQ Helicase Rqh1 Is Required for the Maintenance of Circular Chromosomes
Fission Yeast RecQ Helicase Rqh1 Is Required for the Maintenance of Circular Chromosomes
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DOI：
10.1128/mcb.01713-12
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发表时间：
2013-03-01
影响因子：
5.3
通讯作者：
Ueno, Masaru
中科院分区：
文献类型：
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作者：
Nanbu, Tomoko;Takahashi, Katsunori;Ueno, Masaru
端粒保护蛋白1（Pot1）与单链端粒突出端结合并保护染色体末端。RecQ解旋酶在多个阶段调节同源重组，包括切除、链置换和分解。裂变酵母pot1和RecQ解旋酶rqh1双突变体是合成致死的，但其机制尚未完全了解。在这里，我们表明，pot1三角洲rqh1三角洲双突变体的合成致死性是由于不适当的同源重组，因为它是由rad51（+）的缺失抑制。Rad51在pot1 Delta rqh1 Delta rad51 Delta三重突变体中的表达具有致死性，该突变体具有环状染色体。在具有环状染色体的pot1破坏物中，Rqh 1表达的减少导致染色体误分离，并且该缺陷被rad51（+）的缺失部分抑制。两者合计，我们的研究结果表明，Rqh1是必要的环状染色体的维护时，同源重组是活跃的。环状单体染色体之间的交叉产生二聚体，不能在大肠杆菌中正确分离。我们建议，Rqh1抑制环状单体染色体之间的交叉，以抑制环状二聚体的产生。
Protection of telomeres protein 1 (Pot1) binds to single-stranded telomere overhangs and protects chromosome ends. RecQ helicases regulate homologous recombination at multiple stages, including resection, strand displacement, and resolution. Fission yeast pot1 and RecQ helicase rqh1 double mutants are synthetically lethal, but the mechanism is not fully understood. Here, we show that the synthetic lethality of pot1 Delta rqh1 Delta double mutants is due to inappropriate homologous recombination, as it is suppressed by the deletion of rad51(+). The expression of Rad51 in the pot1 Delta rqh1 Delta rad51 Delta triple mutant, which has circular chromosomes, is lethal. Reduction of the expression of Rqh1 in a pot1 disruptant with circular chromosomes caused chromosome missegregation, and this defect was partially suppressed by the deletion of rad51(+). Taken together, our results suggest that Rqh1 is required for the maintenance of circular chromosomes when homologous recombination is active. Crossovers between circular monomeric chromosomes generate dimers that cannot segregate properly in Escherichia coli. We propose that Rqh1 inhibits crossovers between circular monomeric chromosomes to suppress the generation of circular dimers.