Bacterial CRISPR-Cas systems provide adaptive immunity against viruses and other mobile genome elements. During the adaptation step cells become immunized by insertion of short fragments of foreign DNA, termed spacers, into the genomic region called a CRISPR array. Selection, processing and insertion of new spacers is an elaborate and precisely orchestrated reaction, which relies on the Cas1-Cas2 integrase complex and accessory proteins that vary among different types of CRISPR-Cas systems. This review focuses on CRISPR adaptation from the structural perspective, with the spotlight on adaptation proteins employed by type I and type II CRISPR-Cas systems.

细菌 CRISPR-Cas 系统提供针对病毒和其他移动基因组元件的适应性免疫。在适应步骤中，细胞通过将外源 DNA 的短片段（称为间隔区）插入称为 CRISPR 阵列的基因组区域而获得免疫。新间隔区的选择、加工和插入是一个复杂且精确协调的反应，它依赖于 Cas1-Cas2 整合酶复合物和辅助蛋白，这些蛋白在不同类型的 CRISPR-Cas 系统中有所不同。本综述从结构的角度关注 CRISPR 适应，重点关注 I 型和 II 型 CRISPR-Cas 系统采用的适应蛋白。