Recent reports indicate that the Type six secretion system exported effector 8 (Tse8) is a cytoactive effector secreted by the Type VI secretion system (T6SS) of the human pathogen Pseudomonas aeruginosa. The T6SS is a nanomachine that assembles inside of the bacteria and injects effectors/toxins into target cells, providing a fitness advantage over competing bacteria and facilitating host colonisation. Here we present the first crystal structure of Tse8 revealing that it conserves the architecture of the catalytic triad Lys84-transSer162-Ser186 that characterises members of the Amidase Signature superfamily. Furthermore, using binding affinity experiments, we show that the interaction of phenylmethylsulfonyl fluoride (PMSF) to Tse8 is dependent on the putative catalytic residue Ser186, providing support for its nucleophilic reactivity. This work thus demonstrates that Tse8 belongs to the Amidase Signature (AS) superfamily. Furthermore, it highlights Tse8 similarity to two family members: the Stenotrophomonas maltophilia Peptide Amidase and the Glutamyl-tRNA^Gln amidotransferase subunit A from Staphylococcus aureus.

最近的报告表明，Ť YPE小号IX分泌系统Ë xported效应器8（那么TSE8）是由人类病原体的VI型分泌系统（T6SS）分泌的细胞活性的效应绿脓杆菌。T6SS 是一种纳米机器，可在细菌内部组装并将效应物/毒素注入靶细胞，提供优于竞争细菌的适应性优势并促进宿主定植。在这里，我们展示了 Tse8 的第一个晶体结构，表明它保留了催化三联体 Lys84- trans的结构。Ser162-Ser186 表征酰胺酶特征超家族的成员。此外，使用结合亲和力实验，我们表明苯甲基磺酰氟 (PMSF) 与 Tse8 的相互作用取决于推定的催化残基 Ser186，为其亲核反应性提供支持。因此，这项工作表明 Tse8 属于酰胺酶特征 (AS) 超家族。此外，它突出了那么TSE8相似两名家庭成员：嗜麦芽窄食肽酰胺酶和谷氨酰tRNA^谷氨酰胺酰胺转移酶亚基从一个金黄色葡萄球菌。