Salmonella enterica delivers its genotoxin through outer membrane vesicles secreted from infected cells
Salmonella enterica delivers its genotoxin through outer membrane vesicles secreted from infected cells
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DOI：
10.1111/cmi.12172
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发表时间：
2013-12-01
影响因子：
3.4
通讯作者：
Frisan, Teresa
中科院分区：
文献类型：
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作者：
Guidi, Riccardo;Levi, Laura;Frisan, Teresa
细胞致死膨胀毒素（Cytolethal-膨胀毒素，CDTs）是由革兰氏阴性菌产生的一类DNA损伤诱导外毒素。伤寒沙门氏菌（Salmonella enterica serovar Typhi）仅在感染细胞的含沙门氏菌的空泡（SCV）中表达其CDT（称为伤寒毒素），这需要其输出以用于细胞中毒。其分泌、在细胞外空间释放和被旁观者细胞摄取的机制知之甚少。我们已经使用重组鼠伤寒沙门氏菌菌株MC71-CDT解决了这些问题，其中编码伤寒毒素的PltA、PltB和CdtB亚基的基因在内源性启动子的控制下表达。MC71-CDT在模拟SCV的条件下生长，在外膜囊泡（OMV）中分泌全毒素。感染MC71-CDT的上皮细胞也分泌OMV样囊泡。这些细胞外囊泡的释放需要一个完整的SCV，并依赖于顺行运输到细胞皮质上的微管和肌动蛋白轨道。旁分泌内化伤寒毒素负载OMV的旁观者细胞依赖于发动蛋白-1，表明主动内吞。随后的DNA损伤诱导需要通过高尔基复合体的毒素逆行运输。这些数据提供了新的见解分泌外毒素的细胞感染细胞内细菌的模式。
Cytolethal-distending toxins (CDTs) belong to a family of DNA damage inducing exotoxins that are produced by several Gram-negative bacteria. Salmonella enterica serovar Typhi expresses its CDT (named as Typhoid toxin) only in the Salmonella-containing vacuole (SCV) of infected cells, which requires its export for cell intoxication. The mechanisms of secretion, release in the extracellular space and uptake by bystander cells are poorly understood. We have addressed these issues using a recombinant S.Typhimurium strain, MC71-CDT, where the genes encoding for the PltA, PltB and CdtB subunits of the Typhoid toxin are expressed under control of the endogenous promoters. MC71-CDT grown under conditions that mimic the SCV secreted the holotoxin in outer membrane vesicles (OMVs). Epithelial cells infected with MC71-CDT also secreted OMVs-like vesicles. The release of these extracellular vesicles required an intact SCV and relied on anterograde transport towards the cellular cortex on microtubule and actin tracks. Paracrine internalization of Typhoid toxin-loaded OMVs by bystander cells was dependent on dynamin-1, indicating active endocytosis. The subsequent induction of DNA damage required retrograde transport of the toxin through the Golgi complex. These data provide new insights on the mode of secretion of exotoxins by cells infected with intracellular bacteria.