The deinococcal DdrB protein is involved in an early step of DNA double strand break repair and in plasmid transformation through its single-strand annealing activity.
The deinococcal DdrB protein is involved in an early step of DNA double strand break repair and in plasmid transformation through its single-strand annealing activity.
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DOI：
10.1016/j.dnarep.2011.09.010
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发表时间：
2011-12-10
期刊：
影响因子：
3.8
通讯作者：
Servant P
中科院分区：
文献类型：
--
作者：
Bouthier de la Tour C;Boisnard S;Norais C;Toueille M;Bentchikou E;Vannier F;Cox MM;Sommer S;Servant P
耐辐射球菌细菌对电离辐射表现出极强的抵抗力。在这里，我们研究了DdrB在体内的作用，DdrB是一种辐射诱导的Deinococcus特异性蛋白，以前显示出一些类似于大肠杆菌SSB蛋白的体外特性，但也促进单链DNA的退火。首先，我们报道了DdrB蛋白的c端基序的缺失（类似于修复蛋白募集DNA的SSB c端基序）既不影响细胞的耐辐射性，也不影响纯化的DdrB蛋白的DNA结合特性。我们发现，尽管DdrB和SSB的四元结构不同，但它们在体外对ssDNA的阻断量相同。我们还发现，DdrB在照射到类核后被早期和短暂地招募，形成离散的病灶。通过监测暴露在亚致死电离辐射剂量下的细胞的DNA合成和基因组重组，可以发现DdrB的缺失增加了延伸合成依赖链退火（ESDSA）过程的滞后期，既不影响DNA合成的速率，也不影响片段重组的效率。此外，缺乏DdrB的细胞在自然转化过程中质粒DNA的建立受到影响，这一过程需要将内化的质粒单链DNA片段配对，而它们则熟练地通过染色体DNA标记物通过同源重组整合到宿主染色体中。我们的数据与一个模型一致，在这个模型中，DdrB参与了暴露于非常高辐射剂量的细胞中DNA双链断裂修复的早期步骤。DdrB可能有助于通过单链退火（SSA）工艺精确组装极端辐射暴露产生的无数小片段，从而为后续esdsa促进的基因组重构生成合适的底物。
The Deinococcus radiodurans bacterium exhibits an extreme resistance to ionizing radiation. Here, we investigated the in vivo role of DdrB, a radiation-induced Deinococcus specific protein that was previously shown to exhibit some in vitro properties akin to those of SSB protein from E. coli but also to promote annealing of single stranded DNA. First we report that the deletion of the C-terminal motif of the DdrB protein, which is similar to the SSB C-terminal motif involved in recruitment to DNA of repair proteins, did neither affect cell radioresistance nor DNA binding properties of purified DdrB protein. We show that, in spite of their different quaternary structure, DdrB and SSB occlude the same amount of ssDNA in vitro. We also showed that DdrB is recruited early and transiently after irradiation into the nucleoid to form discrete foci. Absence of DdrB increased the lag phase of the extended synthesis-dependent strand annealing (ESDSA) process, affecting neither the rate of DNA synthesis nor the efficiency of fragment reassembly, as indicated by monitoring DNA synthesis and genome reconstitution in cells exposed to a sub-lethal ionizing radiation dose. Moreover, cells devoid of DdrB were affected in the establishment of plasmid DNA during natural transformation, a process that requires pairing of internalized plasmid single stranded DNA fragments, whereas they were proficient in transformation by a chromosomal DNA marker that integrates into the host chromosome through homologous recombination. Our data are consistent with a model in which DdrB participates in an early step of DNA double strand break repair in cells exposed to very high radiation doses. DdrB might facilitate the accurate assembly of the myriad of small fragments generated by extreme radiation exposure through a single strand annealing (SSA) process to generate suitable substrates for subsequent ESDSA-promoted genome reconstitution.
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影响因子：
4.5
作者：
Bentchikou E;Servant P;Coste G;Sommer S
通讯作者：
Sommer S
影响因子：
3.2
作者：
Morrison, Donald A.;Mortier-Barriere, Isabelle;Claverys, Jean-Pierre
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Claverys, Jean-Pierre
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4.5
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Costes A;Lecointe F;McGovern S;Quevillon-Cheruel S;Polard P
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Polard P
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3.6
作者：
Servant, Pascale;Jolivet, Edmond;Sommer, Suzanne
通讯作者：
Sommer, Suzanne
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3.2
作者：
Meima, R;Rothfuss, HM;Lidstrom, ME
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Lidstrom, ME