OPPA PEPTIDE HOMOLOGUE OF ORAL SPIROCHETES

齿龈密螺旋体表面相关蛋白介导牙周病中螺旋体与龈下组织的相互作用。具有直接细胞病变作用的蛋白质一直是研究的主要焦点。然而，对于这种肽水解和蛋白水解生物必须利用的营养获取机制知之甚少，并且可能利用特定的信号通路或逃避宿主的防御。这些过程可能是许多传染病发展的关键因素。口腔螺旋体的分子遗传学研究对牙周病中螺旋体-宿主相互作用的分析至关重要，有助于了解由病原螺旋体引起的传染病。本研究旨在探讨牙霉OppA在牙周发病中的潜在作用。这种蛋白存在于牙齿菌的表面提取物中，由一个高度保守的遗传位点编码，该基因位点包括oppA、-b、- c、- d和- f，它们是atp结合盒（ABC）转运蛋白家族的组成部分，参与多种细菌的肽营养摄取和跨膜环境信号传导。初步研究表明，OppA结合的可溶性宿主蛋白在发炎的龈下组织中丰富。我们假设OppA与宿主细胞蛋白的结合有助于生物体的发病机制：(i)宿主肽或蛋白质在螺旋体表面的增加，导致宿主反应的调节或逃避；或（ii）肽转运到细胞中用于代谢或环境信号通路。这一建议补充了该实验室正在进行的由外膜孔蛋白和蛋白酶组成的膜复合物组装的研究，并为研究牙周病发病机制中的牙牙分枝杆菌的作用提供了新的方法。重组表达系统将用于研究OppA的结构和功能，并表征其与宿主细胞外基质和牙龈下环境中存在的血清成分的相互作用。对这一假定的转运系统的分子遗传学分析将有助于了解牙周病中细菌与宿主组织成分的相互作用，以及病原螺旋体生物学的基本知识。

Surface-associated proteins of Treponema denticola mediate interactions between the spirochete and sub-gingival tissues in periodontal diseases. Proteins having direct cytopathic effects have been a primary focus of research. However, very little is known of the mechanisms this peptidolytic and proteolytic organism must utilize for nutrient acquisition, and may utilize in specific signaling pathways or in evasion of host defenses. These processes can be key factors in the development of many infectious diseases. Molecular genetic studies of oral spirochetes are crucial to analysis of spirochete-host interactions in periodontal diseases and contribute to understanding infectious diseases caused by frankly pathogenic spirochetes. The present proposal explores the potential role of T. denticola OppA in periodontal pathogenesis. This protein, present in surface extracts of T. denticola, is encoded by a highly conserved genetic locus that includes oppA, -B, -C, -D and -F, the components of an ATP-binding cassette (ABC) transporter family involved in pep-tide nutrient uptake and trans- membrane environmental signaling in a wide range of bacteria. Preliminary studies showed that OppA bound soluble host proteins abundant in inflamed subgingival tissue. We hypothesize that OppA binding of host cell proteins contributes to the pathogenesis of organism by (i) accretion of host peptides or proteins to the spirochete surface, resulting in modulation or evasion of host responses; or (ii) peptide transport into the cell for use in metabolic or environmental signaling pathways. This proposal complements studies underway in this laboratory on assembly of membrane complexes comprised of outer membrane porins and proteases, and includes novel approaches to the study of the role of T. denticola in periodontal pathogenesis. Recombinant expression systems will be used to investigate the structure and function of OppA and to characterize its interaction with host extracellular matrix and serum components present in the subgingival environment. Molecular genetic analysis of this putative transport system will contribute to the understanding of bacterial interactions with host tissue components in periodontal diseases, as well as to basic knowledge of the biology of pathogenic spirochetes.