Regulatory Mechanisms Controlling Expression of P. gingivalis Surface Structures

描述（由申请人提供）：牙周炎是一种生物膜介导的疾病，困扰着美国35%的成年人群，持续感染与全身性疾病相关，包括心血管疾病和中风。龈下缝隙中厌氧菌的增殖是这种慢性疾病进展的核心，牙龈卟啉单胞菌是主要病原体之一。我们最近报道了K抗原荚膜合成的丧失增强了牙龈卟啉单胞菌的生物膜形成，因此调节这种毒力因子在致病性和生物膜形成中起着关键作用。在初步研究中，我们发现与DNA结合蛋白HU（PG 0121）具有高度相似性的基因与K抗原胶囊合成操纵子一起转录，并且这种“组蛋白样”调节蛋白控制胶囊操纵子的表达。我们现在正准备确定控制K抗原胶囊表达的调节机制。我们研究的长期目标是阐明控制牙龈卟啉单胞菌表面特性修饰相关基因表达的调控机制和信号，并确定这些基因表达的变化与生物膜发育和毒力的关系。本申请的目的是表征HU蛋白在K抗原胶囊合成中的作用，并使用染色质免疫沉淀和微阵列分析来研究两个HU亚基（PG0121和PG1258）在调节全局基因表达中的作用。本申请中提出的研究是重要的，因为了解表面性质变化的控制是了解这种细菌从静止状态作为细菌到有毒病原体的转换的重要环节。作为这些研究的结果，我们将确定HU是如何作为一种全局调节蛋白控制关键毒力因子K抗原荚膜的表达的。这些信息将导致更好地理解监管网络，要么直接牙龈卟啉单胞菌成为一种致命的病原体，要么继续保持低调并持续存在。我们的研究结果将可能导致新的治疗策略的发展，用于调节这种口腔病原体的生物膜形成。 公共卫生相关性：牙周病（牙龈）疾病困扰着美国35%的成年人，持续感染与全身性疾病有关，如糖尿病、心血管疾病和中风。牙龈卟啉单胞菌是与严重形式的这种疾病相关的主要口腔病原体之一。本研究的目的是确定控制牙龈卟啉单胞菌产生破坏性因子的重要机制。这些机制本质上是一个“阿喀琉斯之踵”，可以作为一个目标，以阻止这种细菌造成的伤害。

DESCRIPTION (provided by applicant): Periodontitis is a biofilm-mediated disease that afflicts 35% of the adult population in the US, and persistent infections are associated with systemic disease, including cardiovascular disease and stroke. The proliferation of anaerobic bacteria in the subgingival crevice is central to progression of this chronic disease, with Porphyromonas gingivalis being implicated as one of the primary pathogens. We recently reported that a loss in K-antigen capsule synthesis enhanced biofilm formation in P. gingivalis, hence regulation of this virulence factor plays a key role in pathogenicity and biofilm formation. During preliminary studies, we discovered that a gene with high similarity to the DNA binding protein HU (PG0121) is transcribed with the K- antigen capsule synthesis operon and that this "histone-like" regulatory protein controls expression of the capsule operon. We are now poised to determine the regulatory mechanisms controlling expression of K- antigen capsule. The long-term goal of our research is to elucidate the regulatory mechanisms and signals that control the expression of genes involved in modifying the surface properties of P. gingivalis, and to determine how changes in expression of these genes relate to biofilm development and virulence. The objectives of this application are to characterize the role of HU protein in the synthesis of K-antigen capsule and to investigate the role of the two HU subunits (PG0121 and PG1258) in regulating global gene expression using chromatin immunoprecipitation and microarray analysis. The research proposed in this application is significant because understanding the control of surface property changes is a vital link to understanding the switch this bacterium makes from a quiescent state as a commensal to a virulent pathogen. As an outcome of these studies, we will have established how HU a global regulatory protein controls expression of a key virulence factor, K-antigen capsule. This information will lead to a better understanding of the regulatory networks that either direct P. gingivalis to become a virulent pathogen or to continue to lie low and persist. Our results will potentially lead to the development of new therapeutic strategies for modulating biofilm formation by this oral pathogen. PUBLIC HEALTH RELEVANCE: Periodontal (gum) disease afflicts 35% of the adult population in the US, and persistent infections are associated with systemic diseases, such as diabetes, cardiovascular disease, and stroke. The bacterium Porphyromonas gingivalis is one of the primary oral pathogens associated with severe forms of this disease. The goal of this research is to identify vital mechanisms that control the production of destructive factors by P. gingivalis. These mechanisms are in essence an "Achilles heel" that can be used as a target to stop the injury caused by this bacterium.