Structure-based Mechanistic Insights into PAM-dependent Spacer Acquisition in CRISPR/Cas System

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• 英文论文题名：Structure-based Mechanistic Insights into PAM-dependent Spacer Acquisition in CRISPR/Cas System
• 论文作者：Jiiuyu Wang ; Jiazhi Li ; Gang Sheng ; Hongtu Zhao ; Min Wang ; Yanli Wang
• 英文论文作者：Jiiuyu Wang ; Jiazhi Li ; Gang Sheng ; Hongtu Zhao ; Min Wang ; Yanli Wang
• 年：2016
• 会议召开时间：2016-04-27
• 会议录名称：第五届中国结构生物学学术讨论会摘要集
• 语种：英文
• 分类号：Q78
• 学会代码：ZGWI
• 会议名称：第五届中国结构生物学学术讨论会
• 会议地点：中国广东深圳
• 主办单位：中国生物物理学会分子生物物理学专业委员会
• 学会名称：中国生物物理学会
• 页数：1
• 文件大小：75k
• 原文格式：D
• 会议级别：全国

摘要

Bacteria obtain memory of viral invaders by incorporating foreign DNA sequence elements into the host CRISPR locus, generating a new spacer within the CRISPR array. We report a crystal structure of the E. coli Cas1-Cas2-protospacer-DNA complex. We identified the protospacer DNA bound to the Cas1-Cas2 complex, consisting of two Cas1 dimers sandwiching one Cas2 dimer. The protospacer DNA adopts a dual-forked form, with a 23-bp duplex flanked by two 3'-overhangs. Cas1 a cleaves the 3'-overhang at a distance of 5-nt away from the duplex ends, generating a DNA intermediate containing 5-nt 3'-overhangs on both strands. Together with a pair of tyrosine residues, which form a bracket that measures the precise length of the duplex, the Cas1-Cas2 complex predetermines the constant length of the newly acquired spacer. Our studies also showed that Cas1 a recognizes the PAM complementary sequence via sequence specific interactions.
Bacteria obtain memory of viral invaders by incorporating foreign DNA sequence elements into the host CRISPR locus, generating a new spacer within the CRISPR array. We report a crystal structure of the E. coli Cas1-Cas2-protospacer-DNA complex. We identified the protospacer DNA bound to the Cas1-Cas2 complex, consisting of two Cas1 dimers sandwiching one Cas2 dimer. The protospacer DNA adopts a dual-forked form, with a 23-bp duplex flanked by two 3'-overhangs. Cas1 a cleaves the 3'-overhang at a distance of 5-nt away from the duplex ends, generating a DNA intermediate containing 5-nt 3'-overhangs on both strands. Together with a pair of tyrosine residues, which form a bracket that measures the precise length of the duplex, the Cas1-Cas2 complex predetermines the constant length of the newly acquired spacer. Our studies also showed that Cas1 a recognizes the PAM complementary sequence via sequence specific interactions.

引文