CRISPR–Cas systems provide resistance against foreign mobile genetic elements and have a wide range of genome editing and biotechnological applications. In this Review, we examine recent advances in understanding the molecular structures and mechanisms of enzymes comprising bacterial RNA-guided CRISPR–Cas immune systems and deployed for wide-ranging genome editing applications. We explore the adaptive and interference aspects of CRISPR–Cas function as well as open questions about the molecular mechanisms responsible for genome targeting. These structural insights reflect close evolutionary links between CRISPR–Cas systems and mobile genetic elements, including the origins and evolution of CRISPR–Cas systems from DNA transposons, retrotransposons and toxin–antitoxin modules. We discuss how the evolution and structural diversity of CRISPR–Cas systems explain their functional complexity and utility as genome editing tools.

CRISPR-Cas系统可抵抗外来移动遗传元件，并具有广泛的基因组编辑和生物技术应用。在这篇综述中，我们研究了在理解酶的分子结构和机制方面的最新进展，这些酶构成了细菌 RNA 引导的 CRISPR-Cas 免疫系统，并被部署用于广泛的基因组编辑应用。我们探索 CRISPR-Cas 功能的适应性和干扰方面，以及有关基因组靶向分子机制的开放性问题。这些结构见解反映了 CRISPR-Cas 系统和移动遗传元件之间密切的进化联系，包括 CRISPR-Cas 系统从 DNA 转座子、逆转录转座子和毒素-抗毒素模块的起源和进化。我们讨论 CRISPR-Cas 系统的进化和结构多样性如何解释其功能复杂性和作为基因组编辑工具的实用性。