OPPA PEPTIDE HOMOLOGUE OF ORAL SPIROCHETES

齿密螺旋体表面相关蛋白在牙周病中调节螺旋体和牙龈下组织之间的相互作用。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，人们对这种降解多肽和蛋白质的生物体必须用来获取营养的机制知之甚少，也不知道它可能用于特定的信号通路或逃避寄主防御。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于分析牙周疾病中螺旋体与宿主的相互作用至关重要，并有助于了解由螺旋体引起的感染性疾病。本研究旨在探讨齿状毛滴虫在牙周发病机制中的潜在作用。这种蛋白存在于齿纹夜蛾的表面提取物中，由一个高度保守的遗传位点编码，其中包括oppa、-B、-C、-D和-F，它们是一个三磷酸腺苷结合盒(ABC)转运蛋白家族的成员，参与了多种细菌的肽营养吸收和跨膜环境信号转导。初步研究表明，OPPA结合了炎症的龈下组织中丰富的可溶性宿主蛋白。我们假设，宿主细胞蛋白的oppa结合通过(I)宿主多肽或蛋白质聚集到螺旋体表面，导致宿主反应的调节或逃避；或(Ii)多肽运输到细胞内用于代谢或环境信号通路，从而参与生物体的发病。这一建议补充了本实验室正在进行的由外膜孔道蛋白和蛋白酶组成的膜复合体组装的研究，并包括研究齿状毛滴虫在牙周发病中作用的新方法。重组表达系统将被用来研究oppa的结构和功能，并表征其与宿主细胞外基质和存在于龈下环境中的血清成分的相互作用。对这一可能的转运系统的分子遗传学分析将有助于理解牙周病中细菌与宿主组织成分的相互作用，以及病原性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.