Phages counteract bacterial immunity with a myriad different ways

The foundations of molecular biology have been established in the mid of the 20^th century by studying bacteriophages. Restriction-modification systems and CRISPR, tools that have propelled genetic engineering, are systems that bacteria use to defend against phage attack. Yet, only recently we have started to understand how extensive and diverse are interactions between bacteria and phages. Myriads of bacterial immunity systems are being identified, many being the origins of eukaryotic innate immunity systems. Yet how broad is the phage arsenal in counteracting such defense system, and whether phages possess broad-acting anti-defense systems remain unclear at the moment.
Our work builds on our recent discovery that the enigmatic bacterial retrons, the first prokaryotic elements discovered to encode a reverse transcriptase, serve actually as phage defense systems. First, I will show how a functional metagenomics approach enabled us to discover dozens of small phage proteins that block the toxic activity of a specific retron. Then I will present the first novel phage mechanism that allows for broad counteracting of bacterial innate immunity systems.