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一个抗CRISPR病毒环核酶颠覆了CRISPR类型III免疫力
Januka S Athukoralage1, Stephen A McMahon1, Changyi Zhang2,3
1Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews, Fife, UK.
Nature
|January 17, 2020
概括
病毒可以通过使用一种新的酶,AcrIII-1来逃避细菌的CRISPR免疫力,该酶会降解循环四乙烯酸 (cA4) 信号分子. 这一发现揭示了一种新的病毒策略,
科学领域:
- 微生物学
- 分子生物学
- 病毒学
背景情况:
- 克里斯普尔-卡斯系统提供了细胞原体对移动遗传元素的适应性免疫力.
- 第三类CRISPR系统利用Cas10蛋白检测病毒RNA,激活核酶和环酶域合成循环基酸盐.
- 循环基酸盐激活下游的防御酶,形成强大的抗病毒反应,可能导致病毒灭绝.
研究的目的:
- 确定针对III型CRISPR-Cas系统的新型病毒抗CRISPR (Acr) 机制.
- 描述一种新型的病毒酶,可降解循环四乙烯酸 (cA4).
主要方法:
- 生物信息分析以确定AcrIII-1在病毒基因组中的分布.
- 生物化学测试以确定AcrIII-1的基质特异性和酶活性.
- 结构分析以阐明AcrIII-1的结合和催化机制.
主要成果:
- 在古代和细菌病毒中广泛分布的病毒环核酶AcrIII-1的发现.
- AcrIII-1 特别结合并快速降解循环四乙烯酸 (cA4),这是CRISPR 免疫的关键信号分子.
- AcrIII-1 具有新的cA4 结合折和保存的活性部位,有效中和CRISPR防御.
- 通过向信号分子而不是特定的效应蛋白,AcrIII-1家族表现出广泛的宿主范围.
结论:
- AcrIII-1 代表了对III型CRISPR系统的重要病毒反防御机制.
- 通过AcrIII-1降解cA4,使病毒能够脱离CRISPR介导的免疫.
- 循环核酸信号在病毒与宿主之间的共同进化军备竞赛中起着关键作用.
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