The crystal structure of the CRISPR-associated protein Csn2 from Streptococcus agalactiae

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• 作者：Philipp Ellinger^a ; Zihni Arslan^b ; Reinhild Wurm^b ; Britta Tschapek^a ; Colin MacKenzie^c ; Klaus Pfeffer^c ; Santosh Panjikar^e ; ¹ ; Rolf Wagner^b ; Lutz Schmitt^a ; Holger Gohlke^d ; ^{gohlke@hhu.de} ; Ü ; mit Pul^b ; ^pul@hhu.de ; Sander H.J. Smits^a ; ^{sander.smits@hhu.de}
• 关键词：CRISPR ; clustered regularly interspaced short palindromic repeats ; Cas ; CRISPR-associated ; PolDom ; polymerase domain
• 刊名：Journal of Structural Biology
• 出版年：2012
• 期刊代码：92_10478477
• 类别：ph
• 出版时间：June, 2012
• 卷：178
• 期：3
• 页码：350-362
• 文件大小：2031 K

摘要

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 鈥渟it鈥?on the DNA helix and binds DNA in a groove on the outside of the ring.