Salmonella type III effectors PipB and PipB2 are targeted to detergent-resistant microdomains on internal host cell membranes
Salmonella type III effectors PipB and PipB2 are targeted to detergent-resistant microdomains on internal host cell membranes
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DOI：
10.1046/j.1365-2958.2003.03598.x
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发表时间：
2003-08-01
影响因子：
3.6
通讯作者：
Steele-Mortimer, O
中科院分区：
文献类型：
--
作者：
Knodler, LA;Vallance, BA;Steele-Mortimer, O
胞内病原体肠道沙门氏菌将III型效应物穿过其空泡膜转运到宿主细胞中。在此，我们描述了一种新的沙门氏菌效应子，PipB 2，它与另一种III型效应子PipB具有序列相似性。在吞噬细胞中，PipB 2定位于含沙门氏菌的空泡（SCV）和SCV的管状延伸，沙门氏菌诱导的细丝（Sifs）。我们首次利用PipB 2在巨噬细胞中的特异性靶向来表征吞噬细胞中的Sifs。在上皮细胞中，PipB 2具有独特的定位模式，定位于SCV和Sifs，此外还定位于感染细胞周围的囊泡。我们进一步表明，N-末端225个氨基酸残基的PipB 2是足够的III型易位和协会与SCV和SIF，但不是外周囊泡。亚细胞分级分离表明，PipB和PipB 2与宿主细胞膜相关联，并抵抗高盐、高pH和在很大程度上非离子去污剂的提取。此外，PipB和PipB 2富含存在于SCV和Sifs的膜上的耐洗涤剂微区（DRM），也称为脂筏。沙门氏菌效应物在这些细胞内膜上的DRM中的富集可能允许与集中在这些信号平台中的宿主细胞分子的特异性相互作用。
The intracellular pathogen, Salmonella enterica, translocates type III effectors across its vacuolar membrane into host cells. Herein we describe a new Salmonella effector, PipB2, which has sequence similarity to another type III effector, PipB. In phagocytic cells, PipB2 localizes to the Salmonella-containing vacuole (SCV) and tubular extensions from the SCV, Salmonella-induced filaments (Sifs). We used the specific targeting of PipB2 in macrophages to characterize Sifs in phagocytic cells for the first time. In epithelial cells, PipB2 has a unique localization pattern, localizing to SCVs and Sifs and additionally to vesicles at the periphery of infected cells. We further show that the N-terminal 225-amino-acid residues of PipB2 are sufficient for type III translocation and association with SCVs and Sifs, but not peripheral vesicles. Subcellular fractionation demonstrated that both PipB and PipB2 associate with host cell membranes and resist extraction by high salt, high pH and to a significant extent, non-ionic detergent. Furthermore, PipB and PipB2 are enriched in detergent-resistant microdomains (DRMs), also known as lipid rafts, present on membranes of SCVs and Sifs. The enrichment of Salmonella effectors in DRMs on these intracellular membranes probably permits specific interactions with host cell molecules that are concentrated in these signalling platforms.