Primed CRISPR DNA uptake in Pyrococcus furiosus
Primed CRISPR DNA uptake in Pyrococcus furiosus
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DOI：
10.1093/nar/gkaa381
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发表时间：
2020-06-19
影响因子：
14.9
通讯作者：
Terns, Michael P.
中科院分区：
文献类型：
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作者：
Garrett, Sandra;Shiimori, Masami;Terns, Michael P.
CRISPR-Cas适应性免疫系统被原核生物用于防御入侵者，如病毒和其他移动的遗传元件。免疫记忆以“间隔区”的形式存储，这些间隔区是从入侵者中捕获的短DNA序列，并在称为“适应”的过程中添加到CRISPR阵列中。间隔区被转录，并且所得的CRISPR（cr）RNA与不同的Cas蛋白组装以形成识别匹配核酸并破坏它的效应复合物（“干扰”）。适应可以是“天然的”，即不依赖于任何现有的间隔区匹配，或者它可以是“引发的”，即通过crRNA介导的检测与侵入序列的完全或部分匹配而刺激。在这里，我们表明，启动适应发生在激烈的火球菌。虽然P. furiosus有三种不同的CRISPR-Cas干扰系统（I-B，I-A和III-B），但只有I-B系统和Cas 3是引发所必需的。Cas 4对于幼稚适应中新间隔区的选择和加工是重要的，也是引发所必需的。IB效应蛋白或Cas 3的缺失降低了幼稚适应。然而，当Cas 3和所有crRNP基因缺失时，观察到正确加工的间隔区的摄取，表明这些干扰蛋白中没有一个是幼稚适应所必需的。
CRISPR-Cas adaptive immune systems are used by prokaryotes to defend against invaders like viruses and other mobile genetic elements. Immune memories are stored in the form of 'spacers' which are short DNA sequences that are captured from invaders and added to the CRISPR array during a process called 'adaptation'. Spacers are transcribed and the resulting CRISPR (cr)RNAs assemble with different Cas proteins to form effector complexes that recognize matching nucleic acid and destroy it ('interference'). Adaptation can be 'naive', i.e. independent of any existing spacer matches, or it can be 'primed', i.e. spurred by the crRNA-mediated detection of a complete or partial match to an invader sequence. Here we show that primed adaptation occurs in Pyro-coccus furiosus. Although P. furiosus has three distinct CRISPR-Cas interference systems (I-B, I-A and III-B), only the I-B system and Cas3 were necessary for priming. Cas4, which is important for selection and processing of new spacers in naive adaptation, was also essential for priming. Loss of either the IB effector proteins or Cas3 reduced naive adaptation. However, when Cas3 and all crRNP genes were deleted, uptake of correctly processed spacers was observed, indicating that none of these interference proteins are necessary for naive adaptation.