Double-strand DNA end-binding and sliding of the toroidal CRISPR-associated protein Csn2
Double-strand DNA end-binding and sliding of the toroidal CRISPR-associated protein Csn2
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DOI：
10.1093/nar/gkt315
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发表时间：
2013-07-01
影响因子：
14.9
通讯作者：
Pul, Uemit
中科院分区：
文献类型：
--
作者：
Arslan, Zihni;Wurm, Reinhild;Pul, Uemit
细菌针对外来核酸的适应性免疫由 CRISPR（成簇的规则间隔短回文重复序列）介导，依赖于将入侵的外来 DNA 短片段特异性掺入特殊的基因组位点（称为 CRISPR 阵列）。存储的序列（间隔区）随后以小 RNA (crRNA) 的形式用于干扰靶核酸。我们利用不同的生化技术、原子力显微成像和分子动力学模拟，探索了人类病原体无乳链球菌免疫蛋白 Csn2 的 DNA 结合机制。结果表明，环形 Csn2 四聚体通过其中心孔结合 DNA 末端并向内滑动，可能是通过沿着封闭 DNA 的螺旋路径进行螺旋运动。所提供的数据表明 Csn2 在通过末端连接整合外源 DNA 过程中具有辅助功能。
The adaptive immunity of bacteria against foreign nucleic acids, mediated by CRISPR (clustered regularly interspaced short palindromic repeats), relies on the specific incorporation of short pieces of the invading foreign DNA into a special genomic locus, termed CRISPR array. The stored sequences (spacers) are subsequently used in the form of small RNAs (crRNAs) to interfere with the target nucleic acid. We explored the DNA-binding mechanism of the immunization protein Csn2 from the human pathogen Streptococcus agalactiae using different biochemical techniques, atomic force microscopic imaging and molecular dynamics simulations. The results demonstrate that the ring-shaped Csn2 tetramer binds DNA ends through its central hole and slides inward, likely by a screw motion along the helical path of the enclosed DNA. The presented data indicate an accessory function of Csn2 during integration of exogenous DNA by end-joining.