Streptococci are one of the most important and common constituents of the host's microbiota and can colonize and live in the upper respiratory and urogenital tract of humans and animals. The CRISPR-Cas systems (i.e., clustered regularly interspaced short palindromic repeat, with CRISPR-associated proteins) found in bacteria and archaea provide sequence-based adaptive immunity against mobile genetic elements, especially in the streptococci. Here, recent research progress on CRISPR-Cas systems in the streptococci is reviewed, including their classification (mainly type I, type II, and type III), physiological function, defense mechanism (CRISPR adaptation, crRNA biogenesis, and target interference) and applications, which are useful for a better understanding of the functions of such systems. Finally, the advances that have been made in streptococci may help in the discovery of further novel CRISPR-Cas systems for use in new technologies and applications in other species.

中文翻译：

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链球菌中的 CRISPR-Cas 系统。


链球菌是宿主微生物群中最重要和最常见的成分之一，可以在人类和动物的上呼吸道和泌尿生殖道中定殖和生活。在细菌和古细菌中发现的 CRISPR-Cas 系统（即，具有 CRISPR 相关蛋白的成簇规则间隔短回文重复序列）提供针对移动遗传元件（尤其是链球菌）的基于序列的适应性免疫。本文综述了链球菌CRISPR-Cas系统的最新研究进展，包括链球菌的分类（主要为I型、II型和III型）、生理功能、防御机制（CRISPR适应、crRNA生物合成和靶点干扰）和应用，这对于更好地理解此类系统的功能很有用。最后，链球菌方面取得的进展可能有助于发现更多新颖的 CRISPR-Cas 系统，用于其他物种的新技术和应用。