Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn TR10 9FE, UK.
DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
Curr Biol. 2020 Oct 5;30(19):R1189-R1202. doi: 10.1016/j.cub.2020.08.028.
Like many organisms, bacteria and archaea have both innate and adaptive immune systems to defend against infection by viruses and other parasites. Innate immunity most commonly relies on the endonuclease-mediated cleavage of any incoming DNA that lacks a specific epigenetic modification, through a system known as restriction-modification. CRISPR-Cas-mediated adaptive immunity relies on the insertion of short DNA sequences from parasite genomes into CRISPR arrays on the host genome to provide sequence-specific protection. The discovery of each of these systems has revolutionised our ability to carry out genetic manipulations, and, as a consequence, the enzymes involved have been characterised in exquisite detail. In comparison, much less is known about the importance of these two arms of the defence for the ecology and evolution of prokaryotes and their parasites. Here, we review our current ecological and evolutionary understanding of these systems in isolation, and discuss the need to study how innate and adaptive immune responses are integrated when they coexist in the same cell.
与许多生物一样，细菌和古菌都有先天和适应性免疫系统来抵御病毒和其他寄生虫的感染。先天免疫系统最常见的依赖于核酸内切酶介导的切割任何缺乏特定表观遗传修饰的外来 DNA，通过一个称为限制-修饰的系统。CRISPR-Cas 介导的适应性免疫依赖于将寄生虫基因组中的短 DNA 序列插入宿主基因组中的 CRISPR 阵列，以提供序列特异性保护。这些系统中的每一个的发现都极大地提高了我们进行基因操作的能力，因此，相关的酶已被详细地描述。相比之下，对于这些防御系统在原核生物及其寄生虫的生态和进化中的重要性，我们知之甚少。在这里，我们回顾了我们目前对这些系统在孤立状态下的生态和进化的理解，并讨论了需要研究当它们在同一细胞中共存时，先天和适应性免疫反应是如何整合的。
