Botany Department, Faculty of Science, Fayoum University, Fayoum, Egypt.
Arch Microbiol. 2022 Jul 10;204(8):468. doi: 10.1007/s00203-022-03068-5.
T3SS is an important virulence factor of Pseudomonas aeruginosa and has a central role in the infection process. However, the functional regulation of the T3SS by environmental signals is poorly understood. In our lab, we use fluorescence microscopy to study protein kinetics in real-time in live cells. In P. aeruginosa, results have shown that T3SS appears as bright foci at the cell membrane with no specific arrangement. In addition, T3SS is tightly controlled as it appears under a limited time period with the highest intensity at 3 h then disappears. Surprisingly, only 2.5% of the all assembled T3SS in the population have detectable ExoS synthesis. While T3SS assembly and ExoS synthesis increased under high salt concentration, they unexpectedly were not affected by different cyclic di-GMP levels. On the other hand, T3SS itself has an effect on the cyclic di-GMP levels inside the cell. Data have shown that despite T3SS in P. aeruginosa and Yersinia enterocolitica belong to the same the group, the two systems differentiate greatly in activity and regulation. We can conclude that every T3SS is unique and thus further studies are needed to elucidate the functional regulation of each system to better help effective inhibitor design.
T3SS 是铜绿假单胞菌的重要毒力因子，在感染过程中起着核心作用。然而，环境信号对 T3SS 的功能调节还知之甚少。在我们实验室，我们使用荧光显微镜实时研究活细胞中的蛋白质动态。在铜绿假单胞菌中，结果表明 T3SS 以细胞膜上无特定排列的亮焦点形式出现。此外，T3SS 的调控非常严格，它只在有限的时间内出现，强度最高在 3 小时后消失。令人惊讶的是，只有 2.5%的群体中组装好的 T3SS 能够检测到 ExoS 的合成。虽然 T3SS 的组装和 ExoS 的合成在高盐浓度下增加，但它们出人意料地不受不同环二鸟苷酸水平的影响。另一方面，T3SS 本身对细胞内的环二鸟苷酸水平有影响。数据表明，尽管铜绿假单胞菌和肠炎沙门氏菌的 T3SS 属于同一组，但这两个系统在活性和调控方面有很大的不同。我们可以得出结论，每个 T3SS 都是独特的，因此需要进一步研究来阐明每个系统的功能调节，以更好地帮助有效的抑制剂设计。
