DNA degradation (Dnd) is a widespread bacterial antiphage defence system that relies on DNA phosphorothioate (PT) modification for self/non-self discrimination and subsequent degradation of unmodified DNA. Phages employ counterstrategies to evade host immunity, but anti-Dnd immunity has not been characterized. Here we report an immune evasion protein encoded by the Salmonella phage JSS1 that contributes to subverting Dnd and other defence systems. Using quantitative proteomic and phosphoproteomic analyses, we show that the protein JSS1_004 employs N-terminal Ser/Thr/Tyr protein kinase activity to catalyse the multisite phosphorylation of host DndFGH. Notably, JSS1_004 also phosphorylates other bacterial immune systems to varying degrees, including CRISPR‒Cas, QatABCD, SIR2+HerA and DUF4297+HerA. Given that JSS1_004 and its homologues are widespread in phylogenetically diverse phages, we suggest that this strategy constitutes a family of immune evasion proteins that increases the chances of phage proliferation even when a host deploys multiple defence systems.

DNA 降解 （Dnd） 是一种广泛使用的细菌抗噬菌体防御系统，它依赖于 DNA 硫代磷酸酯 （PT） 修饰进行自我/非自我区分和随后对未修饰的 DNA 进行降解。噬菌体采用对抗策略来逃避宿主免疫，但抗 Dnd 免疫尚未得到表征。在这里，我们报道了一种由沙门氏菌噬菌体 JSS1 编码的免疫逃避蛋白，该蛋白有助于破坏 Dnd 和其他防御系统。使用定量蛋白质组学和磷酸化蛋白质组学分析，我们表明该蛋白JSS1_004利用 N 末端 Ser/Thr/Tyr 蛋白激酶活性来催化宿主 DndFGH 的多位点磷酸化。值得注意的是，JSS1_004 还在不同程度上磷酸化其他细菌免疫系统，包括 CRISPR\u2012Cas、QatABCD、SIR2+HerA 和 DUF4297+HerA。鉴于 JSS1_004 及其同源物广泛存在于系统发育多样化的噬菌体中，我们建议该策略构成一个免疫逃避蛋白家族，即使宿主部署多个防御系统，该家族也会增加噬菌体增殖的机会。