The crystal structure of the CRISPR-associated protein Csn2 from Streptococcus agalactiae
The crystal structure of the CRISPR-associated protein Csn2 from Streptococcus agalactiae
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DOI：
10.1016/j.jsb.2012.04.006
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发表时间：
2012-06-01
影响因子：
3
通讯作者：
Smits, Sander H. J.
中科院分区：
文献类型：
--
作者：
Ellinger, Philipp;Arslan, Zihni;Smits, Sander H. J.
原核免疫系统CRISPR赋予了针对移动的遗传元件入侵的适应性和可遗传的防御机制。在小CRISPR RNA（crRNA）的指导下，CRISPR相关（Cas）蛋白的不同家族介导外源DNA的靶向和失活。在这里，我们证明了Csn 2，Cas蛋白可能参与间隔区整合，在溶液中形成四聚体，在结构上具有环状结构。此外，共纯化的Ca 2+被发现对Csn 2的DNA结合特性很重要，Csn 2包含解旋酶折叠，在整个Csn 2蛋白中发现高度保守的DxD和RR基序。我们可以验证Csn 2结合ds-DNA。此外，分子动力学模拟表明，Csn 2构象可以“坐”在DNA螺旋上，并在环外侧的凹槽中结合DNA。(c)2012 Elsevier Inc. All rights reserved.
The prokaryotic immune system, CRISPR, confers an adaptive and inheritable defense mechanism against invasion by mobile genetic elements. Guided by small CRISPR RNAs (crRNAs), a diverse family of CRISPR-associated (Cas) proteins mediates the targeting and inactivation of foreign DNA. Here, we demonstrate that Csn2, a Cas protein likely involved in spacer integration, forms a tetramer in solution and structurally possesses a ring-like structure. Furthermore, co-purified Ca2+ was found important for the DNA binding property of Csn2, which contains a helicase fold, with highly conserved DxD and RR motifs found throughout Csn2 proteins. We could verify that Csn2 binds ds-DNA. In addition molecular dynamics simulations suggested a Csn2 conformation that can "sit" on the DNA helix and binds DNA in a groove on the outside of the ring. (c) 2012 Elsevier Inc. All rights reserved.