a Biology II, Ulm University , Ulm , Germany.
b Microbiology and Biotechnology, Ulm University , Ulm , Germany.
RNA Biol. 2019 Apr;16(4):469-480. doi: 10.1080/15476286.2018.1460994. Epub 2018 May 21.
Invading genetic elements pose a constant threat to prokaryotic survival, requiring an effective defence. Eleven years ago, the arsenal of known defence mechanisms was expanded by the discovery of the CRISPR-Cas system. Although CRISPR-Cas is present in the majority of archaea, research often focuses on bacterial models. Here, we provide a perspective based on insights gained studying CRISPR-Cas system I-B of the archaeon Haloferax volcanii. The system relies on more than 50 different crRNAs, whose stability and maintenance critically depend on the proteins Cas5 and Cas7, which bind the crRNA and form the Cascade complex. The interference machinery requires a seed sequence and can interact with multiple PAM sequences. H. volcanii stands out as the first example of an organism that can tolerate autoimmunity via the CRISPR-Cas system while maintaining a constitutively active system. In addition, the H. volcanii system was successfully developed into a tool for gene regulation.
入侵的遗传元件对原核生物的生存构成了持续的威胁，需要有效的防御。十一年前，CRISPR-Cas 系统的发现扩展了已知防御机制的武器库。尽管 CRISPR-Cas 存在于大多数古菌中，但研究通常集中在细菌模型上。在这里，我们提供了一种基于对古菌 Haloferax volcanii 的 CRISPR-Cas 系统 I-B 的研究获得的观点。该系统依赖于 50 多个不同的 crRNA，其稳定性和维持取决于 Cas5 和 Cas7 这两种蛋白，它们结合 crRNA 并形成 Cascade 复合物。干扰机制需要一个种子序列，并可以与多个 PAM 序列相互作用。H. volcanii 是第一个通过 CRISPR-Cas 系统耐受自身免疫同时保持持续激活系统的生物体的例子。此外，H. volcanii 系统已成功开发为基因调控工具。
