CRISPR-associated proteins 1 and 2 (Cas1–2) are necessary and sufficient for new spacer acquisition in some CRISPR-Cas systems (e.g., type I-E), but adaptation in other systems (e.g., type II-A) involves the crRNA-guided surveillance complex. Here we show that the type I-F Cas1–2/3 proteins are necessary and sufficient to produce low levels of spacer acquisition, but the presence of the type I-F crRNA-guided surveillance complex (Csy) improves the efficiency of adaptation and significantly increases the fidelity of protospacer adjacent motif selection. Sequences selected for integration are preferentially derived from specific regions of extrachromosomal DNA, and patterns of spacer selection are highly reproducible between independent biological replicates. This work helps define the role of the Csy complex in I-F adaptation and reveals that actively replicating mobile genetic elements have antigenic signatures that facilitate their integration during CRISPR adaptation.

中文翻译：

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Type IF CRISPR-Cas 系统可重复的抗原识别


CRISPR 相关蛋白 1 和 2 (Cas1–2) 对于某些 CRISPR-Cas 系统（例如 IE 型）中新间隔区的获取是必要且充分的，但其他系统（例如 II-A 型）中的适应涉及 crRNA-引导监视综合体。在这里，我们证明 IF 型 Cas1-2/3 蛋白对于产生低水平的间隔区获取是必要且充分的，但是 IF 型 crRNA 引导的监视复合物 (Csy) 的存在提高了适应效率并显着提高了保真度原型间隔子相邻基序选择。选择用于整合的序列优先源自染色体外DNA的特定区域，并且间隔区选择的模式在独立的生物复制之间具有高度可重复性。这项工作有助于定义 Csy 复合物在 IF 适应中的作用，并揭示活跃复制的移动遗传元件具有抗原特征，有助于它们在 CRISPR 适应过程中的整合。