Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
Department of Pathology, University of Otago, Dunedin, New Zealand.
Mol Microbiol. 2023 Jul;120(1):32-44. doi: 10.1111/mmi.15034. Epub 2023 Feb 11.
Intracellular bacterial pathogens remodel the plasma membrane of eukaryotic cells in order to establish infection. A common and well-studied mechanism of plasma membrane remodelling involves bacterial stimulation of polymerization of the host actin cytoskeleton. Here, we discuss recent results showing that several bacterial pathogens also exploit the host vesicular trafficking pathway of 'polarized exocytosis' to expand and reshape specific regions in the plasma membrane during infection. Polarized exocytosis is mediated by an evolutionarily conserved octameric protein complex termed the exocyst. We describe examples in which the bacteria Listeria monocytogenes, Salmonella enterica serovar Typhimurium, and Shigella flexneri co-opt the exocyst to promote internalization into human cells or intercellular spread within host tissues. We also discuss results showing that Legionella pneumophila or S. flexneri manipulate exocyst components to modify membrane vacuoles to favour intracellular replication or motility of bacteria. Finally, we propose potential ways that pathogens manipulate exocyst function, discuss how polarized exocytosis might promote infection and highlight the importance of future studies to determine how actin polymerization and polarized exocytosis are coordinated to achieve optimal bacterial infection.
细胞内细菌病原体重塑真核细胞的质膜以建立感染。质膜重塑的一个常见且研究充分的机制涉及细菌刺激宿主肌动蛋白细胞骨架的聚合。在这里，我们讨论了最近的结果，表明几种细菌病原体还利用宿主囊泡运输途径的“极化胞吐作用”在感染过程中扩展和重塑质膜的特定区域。极化胞吐作用是由一个被称为外泌体的进化上保守的八聚体蛋白复合物介导的。我们描述了细菌李斯特菌、沙门氏菌 Typhimurium 和志贺氏菌利用外泌体促进内化进入人细胞或在宿主组织内的细胞间传播的例子。我们还讨论了结果表明，嗜肺军团菌或志贺氏菌操纵外泌体成分来修饰膜囊泡，以有利于细菌的细胞内复制或运动。最后，我们提出了病原体操纵外泌体功能的潜在方式，讨论了极化胞吐作用如何促进感染，并强调了未来研究确定肌动蛋白聚合和极化胞吐作用如何协调以实现最佳细菌感染的重要性。
