RecX facilitates homologous recombination by modulating RecA activities.
RecX facilitates homologous recombination by modulating RecA activities.
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DOI：
10.1371/journal.pgen.1003126
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发表时间：
2012
期刊：
影响因子：
4.5
通讯作者：
Alonso JC
中科院分区：
文献类型：
--
作者：
Cárdenas PP;Carrasco B;Defeu Soufo C;César CE;Herr K;Kaufenstein M;Graumann PL;Alonso JC
枯草芽孢杆菌recH 342菌株，减少种间重组，而不显着影响同配DNA的转化频率，进行了点突变，在推定的recX（yfhG）基因，突变被重命名为recX 342。我们表明，RecX（264个残基长），它与变形菌RecX（<180个残基）部分相同，是一个真正的重组蛋白，其主要功能是调节SOS反应，并促进RecA介导的重组修复和遗传重组。RecX-YFP在类核上形成离散的焦点，其在时间上与RecF一致，响应于DNA损伤，并且在极性和/或类核上随机诱导编程的天然感受态。当DNA被破坏时，RecX焦点与RecA线程共定位，这些线程在recX环境中持续更长时间。RecX的缺失严重损害了质粒和染色体DNA的自然转化。我们表明，RecX抑制质粒转化过程中RecA产生的负面影响，防止RecA错感单链DNA片段，并调节DNA链交换。RecX通过调节RecA细丝的“长度或堆积”，促进重组的起始并增加跨物种的重组。本研究描述了细菌枯草芽孢杆菌通过重组修复（RR）使DNA损伤存活并通过遗传重组（GR）提供遗传变异的机制。在同源重组（HR）的中心是重组酶RecA，它形成RecA·ssDNA丝来介导SOS诱导和促进DNA链交换，这是RR和GR所需的一个步骤。这里提供的遗传数据突出了调节HR活性的RecA辅助因子网络的复杂性，RecX抵消了RecF在SOS诱导中的作用。然而，这两种RecA调节剂的缺乏阻止了RR和GR。提供了对RecA时空募集以保持基因组完整性、克服基因流动障碍以及介体和调节剂对其调节的见解。随着进化距离的增加而下降的染色体转化依赖于HR。事实上，RecX调节剂的存在降低了密切相关的生物体之间的遗传障碍。RecA介质和调制器的保护基因组的完整性和长期的基因组进化的作用进行了讨论。
The Bacillus subtilis recH342 strain, which decreases interspecies recombination without significantly affecting the frequency of transformation with homogamic DNA, carried a point mutation in the putative recX (yfhG) gene, and the mutation was renamed as recX342. We show that RecX (264 residues long), which shares partial identity with the Proteobacterial RecX (<180 residues), is a genuine recombination protein, and its primary function is to modulate the SOS response and to facilitate RecA-mediated recombinational repair and genetic recombination. RecX-YFP formed discrete foci on the nucleoid, which were coincident in time with RecF, in response to DNA damage, and on the poles and/or the nucleoid upon stochastic induction of programmed natural competence. When DNA was damaged, the RecX foci co-localized with RecA threads that persisted for a longer time in the recX context. The absence of RecX severely impaired natural transformation both with plasmid and chromosomal DNA. We show that RecX suppresses the negative effect exerted by RecA during plasmid transformation, prevents RecA mis-sensing of single-stranded DNA tracts, and modulates DNA strand exchange. RecX, by modulating the “length or packing” of a RecA filament, facilitates the initiation of recombination and increases recombination across species. This study describes mechanisms employed by the bacterium Bacillus subtilis to survive DNA damages by recombinational repair (RR) and to provide genetic variation via genetic recombination (GR). At the center of homologous recombination (HR) is the recombinase RecA, which forms RecA·ssDNA filaments to mediate SOS induction and to promote DNA strand exchange, a step needed for both RR and GR. Genetic data presented here highlight the complexity of the network of RecA accessory factors that regulate HR activities, with RecX counteracting the role of RecF in SOS induction. The absence of both RecA modulators, however, blocked RR and GR. Insights into the spatio-temporal recruitment of RecA to preserve genome integrity, to overcome the barriers of gene flow, and its regulation by mediators and modulators are provided. Chromosomal transformation, which declines with increasing evolutionary distance, depends on HR. Indeed, the presence of the RecX modulator decreases the genetic barrier between closely related organisms. The role of RecA mediators and modulators on the preservation of genome integrity and long-term genome evolution is discussed.
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影响因子：
3.6
作者：
GASSEL, M;ALONSO, JC
通讯作者：
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3.2
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