Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, 6997801, Tel Aviv, Israel.
Department of Biotechnology Engineering, ORT Braude College of Engineering, 2161002, Karmiel, Israel.
Nat Commun. 2019 Aug 9;10(1):3595. doi: 10.1038/s41467-019-11546-6.
Bacteria deliver toxic effectors via type VI secretion systems (T6SSs) to dominate competitors, but the identity and function of many effectors remain unknown. Here we identify a Vibrio antibacterial T6SS effector that contains a previously undescribed, widespread DNase toxin domain that we call PoNe (Polymorphic Nuclease effector). PoNe belongs to a diverse superfamily of PD-(D/E)xK phosphodiesterases, and is associated with several toxin delivery systems including type V, type VI, and type VII. PoNe toxicity is antagonized by cognate immunity proteins (PoNi) containing DUF1911 and DUF1910 domains. In addition to PoNe, the effector contains a domain of unknown function (FIX domain) that is also found N-terminal to known toxin domains and is genetically and functionally linked to T6SS. FIX sequences can be used to identify T6SS effector candidates with potentially novel toxin domains. Our findings underline the modular nature of bacterial effectors harboring delivery or marker domains, specific to a secretion system, fused to interchangeable toxins.
细菌通过 VI 型分泌系统（T6SS）传递毒性效应物，以主宰竞争者，但许多效应物的身份和功能仍然未知。在这里，我们鉴定出一种具有先前未描述的广泛存在的 DNase 毒素结构域的 Vibrio 抗菌 T6SS 效应物，我们将其称为 PoNe（多态核酸内切酶效应物）。PoNe 属于 PD-(D/E)xK 磷酸二酯酶的一个多样化超家族，与几种毒素输送系统相关，包括 V 型、VI 型和 VII 型。PoNe 的毒性被含有 DUF1911 和 DUF1910 结构域的同源免疫蛋白（PoNi）拮抗。除了 PoNe，该效应物还包含一个未知功能的结构域（FIX 结构域），该结构域也位于已知毒素结构域的 N 端，并且与 T6SS 在遗传和功能上相关。FIX 序列可用于鉴定具有潜在新型毒素结构域的 T6SS 效应物候选物。我们的发现强调了携带输送或标记结构域的细菌效应物的模块化性质，这些结构域特定于一个分泌系统，并融合了可互换的毒素。
