A bacteriophage encodes its own CRISPR/Cas adaptive response to evade host innate immunity

摘要

Bacteriophages (or phages) are the most abundant biological entities on earth, and are estimated to outnumber their bacterial prey by tenfold1. The constant threat of phage predation has led to the evolution of a broad range of bacterial immunity mechanisms that in turn result in the evolution of diverse phage immune evasion strategies, leading to a dynamic co-evolutionary arms race. Although bacterial innate immune mechanisms against phage abound, the only documented bacterial adaptive immune system is the CRISPR/Cas (clustered regularly interspaced short palin-dromic repeats/CRISPR-associated proteins) system, which provides sequence-specific protection from invading nucleic acids, including phage4"11. Here we show a remarkable turn of events, in which a phage-encoded CRISPR/Cas system is used to counteract a phage inhibitory chromosomal island of the bacterial host. A successful lytic infection by the phage is dependent on sequence identity between CRISPR spacers and the target chromosomal island. In the absence of such targeting, the phage-encoded CRISPR/Cas system can acquire new spacers to evolve rapidly and ensure effective targeting of the chromosomal island to restore phage replication.%CRISPR/Cas细菌适应性免疫系统针对入侵的核酸(包括噬菌体的核酸)提供序列特异性保护。因此，它们是一场持续进行的共演化“军备竞赛“当中的关键武器。在这项研究中，Andrew Camill吸其同事揭示了一个引人瞩目的情况：这些武器被对准了携带它们的细菌。本文作者识别出一个由弧菌噬菌体编码的CRISPR/Cas系统，该系统被用来解除霍乱弧茵中一个噬菌体抑制性染色体岛(crlromosomal islarld)白勺武装。