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穿过液泡膜转运的沙门氏菌效应蛋白与肌动蛋白细胞骨架相互作用。

Salmonella effectors translocated across the vacuolar membrane interact with the actin cytoskeleton.

作者信息

Miao Edward A, Brittnacher Mitchell, Haraga Andrea, Jeng Robert L, Welch Matthew D, Miller Samuel I

机构信息

Department of Microbiology, University of Washington, HSB K-140, Box 357710, Seattle, WA 98195-7710, USA.

出版信息

Mol Microbiol. 2003 Apr;48(2):401-15. doi: 10.1046/j.1365-2958.2003.t01-1-03456.x.

Abstract

A family of nine Salmonella typhimurium type III secretion effectors with a conserved amino-terminus have been defined. Three family members (SifA, SifB and SseJ) have previously been demonstrated to localize to the Salmonella-containing vacuole and to Salmonella-induced filaments. In contrast, we demonstrate that two other family members, SspH2 and SseI, co-localized with the polymerizing actin cytoskeleton. These proteins also interacted with the mammalian actin cross-linking protein filamin in the yeast two-hybrid assay through their highly conserved amino-terminal domains. This amino-terminus was sufficient to direct localization to the polymerizing actin cytoskeleton, suggesting that the interaction with filamin is important for this subcellular localization. In addition, SspH2 co-localized with vacuole-associated actin polymerizations (VAP) induced by intracellular bacteria through the Salmonella pathogenicity island (SPI)-2 type III secretion system (TTSS). SspH2 interacted with the actin-binding protein profilin in the yeast two-hybrid assay and by affinity chromatography. This interaction was highly specific to SspH2 and was mediated by its carboxy-terminus. Furthermore, SspH2 inhibited the rate of actin polymerization in vitro, suggesting that it functions to reduce or remodel VAP. Strains with mutations in sspH2 and sseI retained the ability to form VAP. However, a third intracellular virulence factor, spvB, which ADP-ribosylates actin, strongly inhibited VAP formation in HeLa cells, suggesting a more subtle effect for SspH2 and SseI on the actin cytoskeleton.

摘要

已确定了一个由九个具有保守氨基末端的鼠伤寒沙门氏菌III型分泌效应蛋白组成的家族。先前已证明该家族的三个成员(SifA、SifB和SseJ)定位于含沙门氏菌的液泡和沙门氏菌诱导的丝状结构。相比之下,我们证明另外两个家族成员SspH2和SseI与聚合的肌动蛋白细胞骨架共定位。在酵母双杂交试验中,这些蛋白还通过其高度保守的氨基末端结构域与哺乳动物肌动蛋白交联蛋白细丝蛋白相互作用。这个氨基末端足以指导蛋白定位于聚合的肌动蛋白细胞骨架,这表明与细丝蛋白的相互作用对于这种亚细胞定位很重要。此外,SspH2与细胞内细菌通过沙门氏菌致病岛(SPI)-2 III型分泌系统(TTSS)诱导的液泡相关肌动蛋白聚合(VAP)共定位。在酵母双杂交试验和亲和层析中,SspH2与肌动蛋白结合蛋白原肌球蛋白相互作用。这种相互作用对SspH2具有高度特异性,并由其羧基末端介导。此外,SspH2在体外抑制肌动蛋白聚合速率,表明它起到减少或重塑VAP的作用。sspH2和sseI发生突变的菌株仍保留形成VAP的能力。然而,第三个细胞内毒力因子spvB,它能使肌动蛋白ADP核糖基化,强烈抑制HeLa细胞中VAP的形成,这表明SspH2和SseI对肌动蛋白细胞骨架的影响更为微妙。

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