Salmonella typhimurium SifA effector protein requires its membrane-anchoring C-terminal hexapeptide for its biological function
Salmonella typhimurium SifA effector protein requires its membrane-anchoring C-terminal hexapeptide for its biological function
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DOI：
10.1074/jbc.m207901200
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发表时间：
2003-04-18
影响因子：
4.8
通讯作者：
Méresse, S
中科院分区：
文献类型：
--
作者：
Boucrot, E;Beuzón, CR;Méresse, S
SifA是一种鼠伤寒沙门氏菌效应蛋白，通过沙门氏菌致病岛2编码的III型分泌系统跨含沙门氏菌液泡的膜易位。SifA是形成沙门氏菌诱导的细丝和维持包围病原体的液泡膜所必需的。我们已经研究了作为膜锚定的潜在网站的C-末端六肽的SifA的作用。色葡萄发现携带编码该六肽的序列（sifADelta 6）缺失的鼠伤寒菌株在小鼠中的全身毒力减弱。在小鼠巨噬细胞中，sifADelta 6突变体细菌与空泡标记物的关联减少，类似于sifA无效突变体细菌，并表现出显着的复制缺陷。SifA在上皮细胞中的表达导致溶酶体糖蛋白在大囊泡结构和Sif-like小管中的动员。该过程需要SifA的C-末端六肽结构域的存在。影响C-末端六肽的SifA的截短或突变版本的异位表达揭示了膜结合能力与蛋白质的生物活性之间的强相关性。最后，SifA的11个C-末端残基被证明足以将水母绿色荧光蛋白靶向膜。总之，我们的研究结果表明，SifA的膜锚定需要其C-末端六肽结构域，这对于这种细菌效应器的生物学功能是重要的。
SifA is a Salmonella typhimurium effector protein that is translocated across the membrane of the Salmonella-containing vacuole by the Salmonella pathogenicity island 2-encoded type III secretion system. SifA is necessary for the formation of Salmonella-induced filaments and for the maintenance of the vacuolar membrane enclosing the pathogen. We have investigated the role of the C-terminal hexapeptide of SifA as a potential site for membrane anchoring. An S. typhimurium strain carrying a deletion of the sequence encoding this hexapeptide (sifADelta6) was found to be attenuated for systemic virulence in mice. In mouse macrophages, sifADelta6 mutant bacteria displayed a reduced association with vacuolar markers, similar to that of sifA null mutant bacteria, and exhibited a dramatic replication defect. Expression of SifA in epithelial cells results in the mobilization of lysosomal glycoproteins in large vesicular structures and Sif-like tubules. This process requires the presence of the C-terminal hexapeptide domain of SifA. Ectopic expression of truncated or mutated versions of SifA affecting the C-terminal hexapeptide revealed a strong correlation between the membrane binding capability and the biological activity of the protein. Finally, the eleven C-terminal residues of SifA are shown to be sufficient to target the Aequorea green fluorescent protein to membranes. Altogether, our results indicate that membrane anchoring of SifA requires its C-terminal hexapeptide domain, which is important for the biological function of this bacterial effector.