Comparative genomics and evolution of trans-activating RNAs in Class 2 CRISPR-Cas systems.
Comparative genomics and evolution of trans-activating RNAs in Class 2 CRISPR-Cas systems.
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DOI：
10.1080/15476286.2018.1493331
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发表时间：
2019-04
期刊：
影响因子：
4.1
通讯作者：
Koonin EV
中科院分区：
文献类型：
--
作者：
Faure G;Shmakov SA;Makarova KS;Wolf YI;Crawley AB;Barrangou R;Koonin EV
反式激活CRISPR（tracr）RNA是与CRISPR（cr）RNA相互作用以在II型和亚型V-B CRISPR-Cas系统中形成双向导（g）RNA的独特RNA种类。tracrRNA-crRNA相互作用对于前crRNA加工以及靶标识别和切割是必需的。tracrRNA由反重复序列和远端区域组成，反重复序列与crRNA中的重复序列形成不完美的杂交体，远端区域含有Rho非依赖性终止子。对2类CRISPR向导RNA的序列和预测结构的详尽比较分析显示，所有这些向导RNA共享不同的结构特征，特别是将重复-反重复杂合体与tracrRNA的远端部分分开的连结茎环和杂合体末端的保守GU对。这些结构约束可以确保间隔区完全暴露以用于目标识别。重建的tracrRNA进化为4紧密的细菌群体表现出随机漂移的重复antirepeat互补性内的一个窗口的混合稳定性，显然，保持选择。提出了一种进化方案，其中tracrRNA在多个场合进化，通过CRISPR阵列的重排在相对于阵列的不同位置形成反重复序列。如果在新的位置中，反重复序列的侧翼是满足启动子和Rho非依赖性终止子的最低要求的序列，则会形成功能性tracrRNA。或者，或另外，抗重复序列可以偶尔通过与重复序列重组而“重置”，恢复漂移超过所需最小杂交稳定性的tracrRNA的功能。
Trans-activating CRISPR (tracr) RNA is a distinct RNA species that interacts with the CRISPR (cr) RNA to form the dual guide (g) RNA in type II and subtype V-B CRISPR-Cas systems. The tracrRNA-crRNA interaction is essential for pre-crRNA processing as well as target recognition and cleavage. The tracrRNA consists of an antirepeat, which forms an imperfect hybrid with the repeat in the crRNA, and a distal region containing a Rho-independent terminator. Exhaustive comparative analysis of the sequences and predicted structures of the Class 2 CRISPR guide RNAs shows that all these guide RNAs share distinct structural features, in particular, the nexus stem-loop that separates the repeat-antirepeat hybrid from the distal portion of the tracrRNA and the conserved GU pair at that end of the hybrid. These structural constraints might ensure full exposure of the spacer for target recognition. Reconstruction of tracrRNA evolution for 4 tight bacterial groups demonstrates random drift of repeat-antirepeat complementarity within a window of hybrid stability that is, apparently, maintained by selection. An evolutionary scenario is proposed whereby tracrRNAs evolved on multiple occasions, via rearrangement of a CRISPR array to form the antirepeat in different locations with respect to the array. A functional tracrRNA would form if, in the new location, the antirepeat is flanked by sequences that meet the minimal requirements for a promoter and a Rho-independent terminator. Alternatively, or additionally, the antirepeat sequence could be occasionally ‘reset’ by recombination with a repeat, restoring the functionality of tracrRNAs that drift beyond the required minimal hybrid stability.
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DOI：
10.1126/science.aaf5573
发表时间：
2016-08-05
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Abudayyeh OO;Gootenberg JS;Konermann S;Joung J;Slaymaker IM;Cox DB;Shmakov S;Makarova KS;Semenova E;Minakhin L;Severinov K;Regev A;Lander ES;Koonin EV;Zhang F
通讯作者：
Zhang F
CRISPR-C2C2的两种不同的RNase活性启用了指导RNA处理和RNA检测。
影响因子：
64.8
作者：
East-Seletsky A;O'Connell MR;Knight SC;Burstein D;Cate JH;Tjian R;Doudna JA
通讯作者：
Doudna JA
影响因子：
14.9
作者：
Grissa, Ibtissem;Vergnaud, Gilles;Pourcel, Christine
通讯作者：
Pourcel, Christine
影响因子：
16
作者：
Briner, Alexandra E.;Donohoue, Paul D.;Barrangou, Rodolphe
通讯作者：
Barrangou, Rodolphe
影响因子：
28.3
作者：
Barrangou, Rodolphe;Horvath, Philippe
通讯作者：
Horvath, Philippe