InvB is a type III secretion chaperone specific for SspA
InvB is a type III secretion chaperone specific for SspA
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DOI：
10.1128/jb.182.23.6638-6644.2000
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发表时间：
2000-12-01
影响因子：
3.2
通讯作者：
Miller, SI
中科院分区：
文献类型：
--
作者：
Bronstein, PA;Miao, EA;Miller, SI
各种各样的革兰氏阴性细菌利用一种名为III型分泌系统(TTSS)的特殊装置将毒力因子直接转移到真核细胞的细胞质中。这些易位的效应器有助于病原体在植物和动物宿主内感染和复制。效应蛋白的氨基末端含有TTSS分泌和转位所必需和充分的序列。这些序列的一部分包含III型伴侣的结合位点，这有助于通过TTSS有效地分泌和转移特定的效应物。在这项研究中，我们利用酵母双杂交实验来鉴定沙门氏菌致病岛1(SPI-1)编码的效应蛋白和伴侣蛋白之间的蛋白质-蛋白质相互作用。已鉴定出几种相互作用，包括一种新的作用蛋白SSPA(SipA)与一个可能的伴侣蛋白InvB之间的相互作用，InvB被证明与细菌细胞质中SSPA的氨基末端结合。此外，InvB是SPI-1有效分泌和转运SSPA的III型伴侣。InvB还允许SSPA通过SPI-2 TTSS转运，这表明它是识别SSPA作为TTSS靶标的重要调节因子。最后，确定InvB不会改变SSPA的转录，但它的缺失会导致鼠伤寒沙门氏菌的SSPA蛋白水平降低。
A wide variety of gram-negative bacteria utilize a specialized apparatus called the type III secretion system (TTSS) to translocate virulence factors directly into the cytoplasm of eukaryotic cells. These translocated effecters contribute to the pathogen's ability to infect and replicate within plant and animal hosts. The amino terminus of effector proteins contains sequences that are necessary and sufficient for both secretion and translocation by TTSS. Portions of these sequences contain binding sites for type III chaperones, which facilitate efficient secretion and translocation of specific effecters through TTSS. In this study, we have utilized the yeast two-hybrid assay to identify protein-protein interactions between effector and chaperone proteins encoded within Salmonella pathogenicity island 1 (SPI-1). Several interactions were identified including a novel interaction between the effector protein, SspA (SipA), and a putative chaperone, InvB, InvB was demonstrated to bind to the amino terminus of SspA in the bacterial cytoplasm. Furthermore, InvB acts as a type III chaperone for the efficient secretion and translocation of SspA by SPI-1. InvB also permitted translocation of SspA through the SPI-2 TTSS, indicating that it is an important regulator in the recognition of SspA as a target of TTSS. Finally, it was determined that InvB does not alter the transcription of sspA but that its absence results in reduced SspA protein levels in Salmonella enterica serovar Typhimurium.