Interactions between Brucella suis VirB8 and Its Homolog TraJ from the Plasmid pSB102 Underline the Dynamic Nature of Type IV Secretion Systems
Interactions between Brucella suis VirB8 and Its Homolog TraJ from the Plasmid pSB102 Underline the Dynamic Nature of Type IV Secretion Systems
复制标题
DOI：
10.1128/jb.01426-08
复制
发表时间：
2009-05-01
影响因子：
3.2
通讯作者：
Patey, Gilles
中科院分区：
文献类型：
--
作者：
Bourg, Gisele;Sube, Romain;Patey, Gilles
VirB8蛋白在根癌农杆菌（Agrobacterium tumefaciens）virB IV型分泌系统（T4SS）的组装和功能中起关键作用。对A.已经确定了根癌农杆菌和猪布鲁氏菌VirB8，并且定点诱变已经揭示了参与VirB8的二聚化以及与VirB4和VirB10的相互作用的氨基酸。我们以前已经证明TraJ、来自pSB 102的VirB 8同源物和嵌合蛋白TraJB 8（包括TraJ的胞质和跨膜（TM）结构域以及VirB 8的周质结构域）不能与B互补。含有virB8基因框内缺失的猪突变体。这表明TraJ胞质和TM结构域的存在可以阻断VirB8在内膜中的二聚化或组装。通过细菌双杂交分析，我们发现VirB8，TraJ和嵌合体都可以相互作用形成同源和异源二聚体。然而，TraJ的TM结构域的存在导致同源二聚体和异源二聚体中的相互作用强得多。我们在野生型B中表达了野生型和嵌合蛋白。猪。携带TraJ TM结构域的蛋白质的存在具有显性负效应，导致毒力完全丧失。这表明T4SS是一个动态结构，强烈的相互作用阻碍了正确组装和功能所需的空间灵活性。
The protein VirB8 plays a critical role in the assembly and function of the Agrobacterium tumefaciens virB type IV secretion system (T4SS). The structure of the periplasmic domain of both A. tumefaciens and Brucella suis VirB8 has been determined, and site-directed mutagenesis has revealed amino acids involved in the dimerization of VirB8 and interactions with VirB4 and VirB10. We have shown previously that TraJ, the VirB8 homologue from pSB102, and the chimeric protein TraJB8, encompassing the cytoplasmic and transmembrane (TM) domains of TraJ and the periplasmic domain of VirB8, were unable to complement a B. suis mutant containing an in-frame deletion of the virB8 gene. This suggested that the presence of the TraJ cytoplasmic and TM domains could block VirB8 dimerization or assembly in the inner membrane. By bacterial two-hybrid analysis, we found that VirB8, TraJ, and the chimeras can all interact to form both homo-and heterodimers. However, the presence of the TM domain of TraJ resulted in much stronger interactions in both the homo- and heterodimers. We expressed the wild-type and chimeric proteins in wild-type B. suis. The presence of proteins carrying the TM domain of TraJ had a dominant negative effect, leading to complete loss of virulence. This suggests that the T4SS is a dynamic structure and that strong interactions block the spatial flexibility required for correct assembly and function.