Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
Cell Host Microbe. 2010 Jun 25;7(6):453-62. doi: 10.1016/j.chom.2010.05.011.
Shifts in electrostatic surface charge of membranes have recently been highlighted as a significant factor contributing to protein targeting to the plasma membrane and nascent phagosomes. Intracellular, vacuole-adapted pathogens may also regulate surface charge of their vacuoles to establish a replicative niche. Since Salmonella enterica serovar Typhimurium controls trafficking of the Salmonella-containing vacuole (SCV) and inhibits its fusion with lysosomes, we investigated the contribution of surface charge to this process. Using recently developed fluorescent biosensors, we show that the bacterial phosphoinositide phosphatase SopB controls membrane surface charge of nascent SCVs by reducing levels of negatively charged lipids phosphatidylinositol-4,5-bisphosphate and phosphatidylserine. This SopB activity results in dissociation of a number of host-cell endocytic trafficking proteins from this compartment and inhibits SCV-lysosome fusion. Moreover, inducible reduction of negative charge rescues DeltasopB bacteria-containing SCVs from fusion with lysosomes. These results reveal a membrane-charge-based mechanism used by S. Typhimurium to control SCV maturation.
最近，人们强调细胞膜静电表面电荷的转移是导致蛋白质靶向质膜和新生吞噬体的重要因素。细胞内，适应空泡的病原体也可能调节空泡的表面电荷，以建立一个复制龛位。由于沙门氏菌肠炎血清型 Typhimurium控制含沙门氏菌的空泡 (SCV) 的运输，并抑制其与溶酶体融合，我们研究了表面电荷对这一过程的贡献。使用最近开发的荧光生物传感器，我们表明，细菌磷酸肌醇磷酸酶 SopB 通过降低带负电荷的脂质磷脂酰肌醇-4,5-二磷酸和磷脂酰丝氨酸的水平来控制新生 SCV 的膜表面电荷。这种 SopB 活性导致许多宿主细胞内吞运输蛋白从该隔室解离，并抑制 SCV-溶酶体融合。此外，诱导性负电荷减少可使含有 DeltasopB 细菌的 SCV 免于与溶酶体融合。这些结果揭示了沙门氏菌肠炎血清型 Typhimurium 用于控制 SCV 成熟的基于膜电荷的机制。
