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Structural and Mechanistic Basis of PAM-Dependent Spacer Acquisition in CRISPR-Cas Systems, Cell, Volume 163, Issue 4, p840–853, 5 November 2015

发布时间:2015年11月10日

Cell, Volume 163, Issue 4, p840–853, 5 November 2015, DOI: http://dx.doi.org/10.1016/j.cell.2015.10.008

Structural and Mechanistic Basis of PAM-Dependent Spacer Acquisition in CRISPR-Cas Systems

Jiuyu Wang4,  Jiazhi Li4, Hongtu Zhao, Gang Sheng, Min Wang, Maolu Yin,  Yanli Wang

Summary

Bacteria acquire memory of viral invaders by incorporating invasive DNA sequence elements into the host CRISPR locus, generating a new spacer within the CRISPR array. We report on the structures of Cas1-Cas2-dual-forked DNA complexes in an effort toward understanding how the protospacer is sampled prior to insertion into the CRISPR locus. Our study reveals a protospacer DNA comprising a 23-bp duplex bracketed by tyrosine residues, together with anchored flanking 3′ overhang segments. The PAM-complementary sequence in the 3′ overhang is recognized by the Cas1a catalytic subunits in a base-specific manner, and subsequent cleavage at positions 5 nt from the duplex boundary generates a 33-nt DNA intermediate that is incorporated into the CRISPR array via a cut-and-paste mechanism. Upon protospacer binding, Cas1-Cas2 undergoes a significant conformational change, generating a flat surface conducive to proper protospacer recognition. Here, our study provides important structure-based mechanistic insights into PAM-dependent spacer acquisition.

相关报道:http://www.ibp.cas.cn/kyjz/zxdt/201510/t20151016_4439718.html

文章链接:http://www.cell.com/cell/abstract/S0092-8674(15)01321-5

 

 

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