Systematic discovery of anti-phage defense systems in the microbialpan-genome

摘要

The arms race between bacteria and phages led to the development of sophisticated anti-phage defense systems, including CRISPR-Cas and restriction-modification systems. Evidence suggests that unknown defense systems are located in “defense islands” in microbial genomes. We comprehensively characterized the bacterial defensive arsenal by examining gene families that are clustered next to known defense genes in prokaryotic genomes. Candidate defense systems were systematically engineered and validated in model bacteria for their anti-phage activities. We report nine previously unknown anti-phage and one anti-plasmid systems that are widespread in microbes and strongly protect against foreign invaders. These include systems that adopted components of the bacterial flagella and condensin complexes. Our data also suggest a common, ancient ancestry of innate immunity components shared between animals, plants and bacteria.