We characterize the anti-phage function of a type IV TA system, ShosTA toxin-antitoxin system provides phage defense via DNA damage and repair

Widespread in bacteria and archaea, Toxin-antitoxin (TA) systems have been recently demonstrated to function in phage defense. Here we characterize the anti-phage function of a type IV TA system, ShosTA. Using structural and biochemical approaches, we show that ShosT couples phosphoribosyltransferase and pyrophosphatase activities to disrupt purine metabolism, resulting in DNA duplication, cell filamentation and ultimate cell death. ShosA binds DNA and likely recruits other proteins to facilitate DNA recombination to antagonize ShosT’s toxicity