In Escherichia coli, the Twin-arginine translocation (Tat) pathway secretes a set of folded proteins with important physiological functions to the periplasm and outer membrane. The loss of Tat secretion impairs outer membrane integrity and leads to decreased cell growth. Only recently, the Tat pathway has gained more attention due to its essential role in bacterial virulence and applications in the production of fully folded heterologous proteins. In this study, we investigated the influence of the deletion of all active Tat pathway components on the E. coli cells. The comprehensive proteomic analysis revealed activation of several stress responses and experimentally confirmed the dependence of certain proteins on the Tat system for export. We observed that a tat deletion triggers protein aggregation, membrane vesiculation, synthesis of colanic acid and biofilm formation. Furthermore, the mislocalization of Tat-dependent proteins disturbs iron and molybdenum homeostasis and impairs the cell envelope integrity. The results show that the functional Tat pathway is important for the physiological stability and that its dysfunction leads to a series of severe changes in E. coli cells.

在大肠杆菌中，双精氨酸易位（Tat）途径向周质和外膜分泌了一组具有重要生理功能的折叠蛋白。Tat分泌的损失会损害外膜的完整性，并导致细胞生长下降。直到最近，由于其在细菌毒力中的重要作用以及在完全折叠的异源蛋白生产中的应用，Tat途径才获得更多关注。在这项研究中，我们调查了所有活跃的Tat通路成分的缺失对大肠杆菌细胞的影响。全面的蛋白质组学分析揭示了几种应激反应的激活，并通过实验证实了某些蛋白质对出口的Tat系统的依赖性。我们观察到，一达缺失触发蛋白质聚集，膜囊泡形成，可乐酸合成和生物膜形成。此外，Tat依赖蛋白的错误定位会干扰铁和钼的稳态，并损害细胞膜的完整性。结果表明，功能性Tat通路对于生理稳定性很重要，其功能障碍会导致大肠杆菌细胞发生一系列严重变化。