Salmonella InvG forms a ring-like multimer that requires the InvH lipoprotein for outer membrane localization
Salmonella InvG forms a ring-like multimer that requires the InvH lipoprotein for outer membrane localization
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DOI：
10.1046/j.1365-2958.1998.01036.x
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发表时间：
1998-10-01
影响因子：
3.6
通讯作者：
Koronakis, V
中科院分区：
文献类型：
--
作者：
Crago, AM;Koronakis, V
沙门氏菌属物种通过由致病性岛-1（SPI-1）编码的III型分泌装置将毒力效应蛋白从细菌细胞质转运到哺乳动物宿主细胞中。关于这种分泌装置的组装和结构知之甚少，但InvG蛋白是必需的，并且可能是效应蛋白的外膜分泌通道。我们观察到，在重组大肠杆菌中，InvG的产量提高了共表达的InvH，并表明，invH的突变降低了野生型鼠伤寒沙门氏菌中的InvG的水平。在大肠在大肠杆菌中，单独的InvG能够形成抗SDS的多聚体，但是InvG定位于外膜依赖于InvH，即位于外膜中的脂蛋白本身，而没有其他SPI-1特异性蛋白。InvG被InvH靶向到外膜，变得可接近胞外蛋白酶。然而，InvG和InvH似乎没有形成稳定的复合物。电镜观察纯化的E.大肠杆菌中的表达结果表明，该蛋白形成了一个寡聚环状结构，其内径和外径分别为7 nm和15 nm
Salmonella species translocate virulence effector proteins from the bacterial cytoplasm into mammalian host cells by means of a type III secretion apparatus, encoded by the pathogenicity island-1 (SPI-1). Little is known about the assembly and structure of this secretion apparatus, but the InvG protein is essential and could be an outer membrane secretion channel for the effector proteins. We observed that in recombinant Escherichia coli, the yield of InvG was enhanced by coexpression of InvH, and showed that mutation of invH decreased the level of InvG in wild-type Salmonella typhimurium. In E. coli, InvG alone was able to form an SDS-resistant multimer, but InvG localization to the outer membrane was dependent upon InvH, a lipoprotein itself located in the outer membrane, and no other SPI-1 specific protein. InvG targeted to the outer membrane by InvH became accessible to extracellular protease. InvG and InvH did not, however, appear to form a stable complex. Electron microscopy of InvG membrane protein purified from E. coli revealed that it forms an oligomeric ring-like structure with inner and outer diameters, 7 nm and 15 nm respectively