Outer Membrane Proteins of Borrelia burgdorferi

项目摘要 莱姆病已经成为一个世界性的公共卫生问题，现在是最常见的扁虱传播疾病。 在美国和欧洲感染。为了更好地了解伯氏疏螺旋体，致病因子 莱姆病，在受感染的扁虱和哺乳动物中持续存在，许多实验室都专注于识别和 这种螺旋体的外表面蛋白的特征。伯氏杆菌与其扁虱之间的界面或 哺乳动物宿主是其外表面，因此外膜蛋白(OMP)定位于其表面。 这种微生物在致病和致病中起着重要作用。按照这些思路，在上一个资助期，我们 重点研究了外膜蛋白系统将OMPS输出到B。 勃格多费里。这种名为β-Barrel装配机的出口设备由三个部件组成 伯氏杆菌的主要外膜蛋白OMP BAMA和两种辅助脂蛋白BAMB 和BAMD。最近在一些双膜细菌中发现了第二个OMP转运系统 (即既有内膜又有外膜的细菌)，被称为易位 和装配模块()系统。系统由OMP指定的TAMA和一个单一的 内膜(IM)蛋白，指定为TAMB。虽然BAM系统输出了大部分OMP，但 系统现在已知输出各种自体转运蛋白和其他与毒力相关的OMP。在.期间 我们的研究表征了硼质BAM出口复合体，我们还鉴定了一种假想的硼质蛋白， BB0794的同源基因，我们确定该基因是一种脆性TAMB同源基因。有趣的是，几乎所有的双膜片 到目前为止，已发现具有特征的生物体编码TAMB同源基因，但仅编码变形杆菌 包含完整的系统，由多摩和坦博组成。TAMB在ALL中的功能作用 因此，缺乏TAMA的双膜生物，包括B.burgdorferi，仍然是一个未回答的问题。 问题。然而，我们最近的研究可能最终回答了这个问题，因为我们发现 鱼腥草TAMB蛋白与BAM复合体的BAMA特异相互作用。与TAB是一致的 参与OMP输出和外膜生物发生，我们观察到TAMB突变体改变了细胞 形态和对抗生素的敏感性增加。综合这些发现，我们提出了一个新的 TAMB同源基因在双膜生物中的功能作用，如螺旋体。潜在的 我们提出的研究假设是，更好地了解B. 伯格多费氏菌将导致新的毒力因子和莱姆氏疫苗候选的鉴定 疾病。重要的是，我们在本申请中提出的研究也可能改变目前的 许多细菌病原体中OMP输出和外膜生物发生的范例。

Project Summary Lyme disease has become a worldwide public health problem and is now the most common tick-borne infection in the United States and Europe. To better understand how Borrelia burgdorferi, the causative agent of Lyme disease, persists in the infected tick and mammal, many laboratories have focused on identifying and characterizing outer surface proteins from this spirochete. The interface between B. burgdorferi and its tick or mammalian host is its outer surface; therefore, outer membrane proteins (OMPs) localized to the surface of this organism play an important role in virulence and disease. Along these lines, in the last funding period we focused on characterizing the outer membrane protein system that exports OMPs to the surface of B. burgdorferi. This OMP export complex, termed the β-barrel assembly machine (BAM), is comprised of three major outer membrane proteins in B. burgdorferi, the OMP BamA along with two accessory lipoproteins, BamB and BamD. A second OMP transport system has recently been identified in some dual-membraned bacteria (i.e., bacteria with both an inner membrane and an outer membrane), which has been named the translocation and assembly module (TAM) system. The TAM system consists of the OMP designated TamA and a single inner membrane (IM) protein designated TamB. While the BAM system exports the majority of OMPs, the TAM system is now known to export various autotransporters and other virulence-associated OMPs. During our studies characterizing the borrelial BAM export complex, we also identified a hypothetical borrelial protein, BB0794, which we determined is a borrelial TamB ortholog. Interestingly, almost all dual-membraned organisms characterized to date have been found to encode a TamB ortholog, but only the Proteobacteria contain the complete TAM system comprised of both TamA and TamB. The functional role of TamB in all dual-membraned organisms lacking TamA, including B. burgdorferi, has therefore remained an unanswered question. Our recent studies, however, may have finally answered this question as we discovered that the borrelial TamB protein specifically interacts with BamA of the BAM complex. Consistent with TamB being involved in OMP export and outer membrane biogenesis, we observed that a TamB mutant has altered cellular morphology and increased sensitivity to antibiotics. The combined findings lead us to propose a new functional role for TamB orthologs in dual-membraned organisms, such as spirochetes. The underlying hypothesis of our proposed studies is that a better understanding of the OMP export systems in B. burgdorferi will lead to the identification of novel virulence factors and vaccine candidates for Lyme disease. Importantly, the studies we propose in this application could also change the current paradigm of OMP export and outer membrane biogenesis in many bacterial pathogens.