Molecular Aspects of Oral Plaque Formation

描述(由申请人提供)：牙周病，人类最常见的感染之一，具有多菌病原学，微生物组表现出协同致病作用。作为研究多菌种协同作用的一个模型系统，我们正在研究P.gigivalis-S。戈登尼氏相互作用。斑块的早期殖民者戈登氏链霉菌 生物膜，为更具致病性的后来的定殖者牙龈假单胞菌提供附着底物。接触依赖的信号和代谢物的感知启动了牙龈假单胞菌的进一步积累和双物种群落的发展。种间黏附是由牙龈假单胞菌的短菌毛(由Mfa1结构亚基组成)介导的，它与戈登链霉菌的SSP表面蛋白结合。在SspB中，一个区域1167-1193残基(指定的bar)内的几个氨基酸基序决定了结合活性和特异性。群落发育的发展和后来的限制依赖于牙龈假单胞菌内酪氨酸磷酸化(通过激酶Ptk1)和去磷酸化(通过磷酸酶LTP1)的平衡，它控制着群落效应分子如Mfa1和LuxS的表达。这种依赖酪氨酸(去磷酸化)的信号转导途径也汇聚在编码蛋白酶的表达基因上，在小鼠牙槽骨丢失模型中，牙龈假单胞菌和戈登葡萄球菌的双重物种群落比单独的任一物种更具致病性。本研究的目的是：i)确定与SspB的bar结构域相互作用的Mfa1的结构和功能基序；ii)确定牙龈假单胞菌酪氨酸激酶Ptk1在控制戈登链球菌异型群落发育的调控网络中的作用；以及iii)确定牙龈假单胞菌对链球菌代谢物4-氨基苯甲酸酯(PABA)的反应，PABA调节群落的发育和致病潜力。这些目标的成功完成将为牙龈假单胞菌Mfa1菌毛粘附素提供新的结构和功能信息。此外，我们还将揭示酪氨酸激酶(Ptk1)和磷酸酶(LTP1)在调节群落发育的信号转导事件中的相互作用。我们还将产生关于代谢物感知及其在社区发展和致病潜力中的作用的新信息。我们广泛的长期目标是将这一基本的机制信息转化为针对病原群落抑制的治疗干预的新靶点的识别。由于单一靶点干预的效用有限，而且尚未在牙周治疗选择上产生任何重大进展，因此干扰致病群落发展的多个组成部分，包括粘连和成熟事件，可能有更大的成功可能性。

DESCRIPTION (provided by applicant): Periodontal disease, one of the most common infections of humans, has a polymicrobial etiology whereby groups of microorganisms exhibit synergistic pathogenicity. As a model system for the study of polymicrobial synergy we are investigating P. gingivalis-S. gordonii interactions. S. gordonii, an early colonizer of the plaque biofilm, provides an attachment substratum for the more pathogenic later colonizer P. gingivalis. Contact dependent signaling and metabolite perception initiate further accumulation of P. gingivalis and the development of a dual species community. Interspecies coadhesion is mediated by the short fimbriae (comprised of the Mfa1 structural subunit) of P. gingivalis that engage the Ssp surface proteins of S. gordonii. Within SspB several amino acid motifs within a region spanning residues 1167-1193 (designated BAR), dictate binding activity and specificity. Development, and later constraint, of community development depends on the balance of tyrosine phosphorylation (through the kinase Ptk1) and dephosphorylation (through the phosphatase Ltp1) within P. gingivalis, which controls expression of community effectors such as Mfa1 and LuxS. This tyrosine (de)phosphorylation dependent signal transduction pathway also converges on the expression genes encoding proteases, and a dual species community of P. gingivalis and S. gordonii is more pathogenic compared to either species alone in a murine alveolar bone loss model. The objectives of this study are to: i) characterize the structural and functional motifs of Mfa1 that interact with the BAR domain of SspB; ii) define the role of the P. gingivalis tyrosine kinase Ptk1 in regulatory networks that control heterotypic community development with S. gordonii; and iii) determine the responses of P. gingivalis to the streptococcal metabolite 4-aminobenzoate (pABA) that regulate community development and pathogenic potential. Successful completion of these objectives will provide novel structure and function information on the P. gingivalis Mfa1 fimbrial adhesin. In addition, we will unravel the interplay between tyrosine kinase (Ptk1) and phosphatase (Ltp1) activities in the signal transduction events that regulate community development. We will also generate novel information regarding metabolite sensing and its role in both community development and pathogenic potential. Our broad long-term goal is to translate this fundamental mechanistic information into the identification of novel targets for therapeutic intervention directed toward pathogenic community inhibition. As single target intervention can have limited utility, and has yet to yield any significant advances in periodontal therapeutic options, interference with multiple components of pathogenic community development, including adhesive and maturation events, may have a greater likelihood of success.