Characterization of Salmonella-induced filaments (Sifs) reveals a delayed interaction between Salmonella-containing vacuoles and late endocytic compartments
Characterization of Salmonella-induced filaments (Sifs) reveals a delayed interaction between Salmonella-containing vacuoles and late endocytic compartments
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DOI：
10.1034/j.1600-0854.2001.20907.x
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发表时间：
2001-09-01
期刊：
影响因子：
4.5
通讯作者：
Finlay, BB
中科院分区：
文献类型：
--
作者：
Brumell, JH;Tang, P;Finlay, BB
鼠伤寒沙门氏菌是一种兼性细胞内病原体，在整个感染过程中定植于宿主细胞。这种病原体的一个独特特征是它能够进入(入侵)上皮细胞，并将其所在的空泡拉长成称为沙门氏菌诱导细丝(SIFs)的管状结构。在这项研究中，我们试图通过使用亚细胞标记物的免疫荧光分析来表征SIF的形成机制。晚期内体脂质溶二磷脂酸与含有沙门氏菌的空泡呈点状伴生，开始于感染后90分钟，之后逐渐增加。溶二磷脂酸丰富的囊泡也被发现与SIFs相互作用，在沿小管的许多位置。同样，富含胆固醇的小泡也与细胞内细菌和SIFs有关。溶酶体水解酶组织蛋白酶D存在于SIF中，既有点状分布，也有以后以不间断的线状分布为主。与Sifs结合的Rab7和该GTPase的显性负性突变体N1251的表达抑制了Sif的形成。用融合到绿色荧光蛋白上的编码SifA的载体转染HeLa细胞，引起含有溶二磷脂酸的隔室的肿胀和聚集，表明这种毒力因子指导了涉及晚期内小体的膜融合事件。我们的发现表明，Sif的形成涉及晚期内吞液室与含有沙门氏菌的液泡的融合，并表明SifA调节这一事件。
Salmonella typhimurium is a facultative intracellular pathogen that colonizes host cells throughout the course of infection. A unique feature of this pathogen is its ability to enter into (invade) epithelial cells and elongate the vacuole within which it resides into tubular structures called Salmonella-induced filaments (Sifs). In this study we sought to characterize the mechanism of Sif formation by immunofluorescence analysis using subcellular markers. The late endosomal lipid lysobisphosphatidic acid associated in a punctate pattern with the Salmonella-containing vacuole, starting 90 min after infection and increasing thereafter. Lysobisphosphatidic acid-rich vesicles were also found to interact with Sifs, at numerous sites along the tubules. Similarly, cholesterol-rich vesicles were also found in association with intracellular bacteria and Sifs. The lysosomal hydrolase cathepsin D was present in Sifs, both in a punctate pattern and, at later times, predominantly in an uninterrupted linear pattern. Rab7 associated with Sifs and expression of the N1251 dominant negative mutant of this GTPase inhibited Sif formation. Transfection of HeLa cells with a vector encoding SifA fused to the green fluorescent protein caused swelling and aggregation of lysobisphosphatidic acid-containing compartments, suggesting that this virulence factor directs membrane fusion events involving late endosomes. Our findings demonstrate that Sif formation involves fusion of late endocytic compartments with the Salmonella-containing vacuole, and suggest that SifA modulates this event.