Regulatory Mechanisms Controlling Expression of P. gingivalis Surface Structures

 描述（由申请人提供）：牙龈卟啉单胞菌（Pg）是一种革兰氏阴性厌氧菌，与成人牙周病的病因密切相关。这项研究将增加我们对控制Pg细胞表面聚糖合成的分子机制的理解，并确定合成的变化如何与生物膜持久性和致病性相关。我们的总体模型是，生物膜状态作为细菌的水库，而胶囊合成与毒性和破坏稳态的过渡。我们已经发现Pg中的DNABII家族成员（HU PG 0121和HU PG 1258）参与控制这种表面多糖的合成。DNABII蛋白是类核相关蛋白（NAPs）的成员，类核相关蛋白是一类在维持DNA和RNA的结构和功能方面具有多种功能的蛋白，并且已知对于调节细胞代谢、对环境扰动的响应以及控制向和从静止状态的转变是关键的。我们还鉴定了一个反义RNA，它编码于荚膜位点（PG 0104-PG 0121）的5 ′端，位于一个大的77 bp反向重复序列（77 bpIR）元件内。编码该asRNA的区域的缺失或过表达改变了LPS和K抗原囊的合成。我们的工作模型是DNABII蛋白与该asRNA相互作用，并控制该区域正义和反义转录物的表达。我们将asRNA命名为SuGR，即反义表面聚糖调节剂。该项目的中心假设是HU PG 0121和HU PG 1258是在调节Pg致病性中发挥基本作用的关键NAP。在这些研究中，我们将确定这些蛋白质和77 bpIR元件如何控制胶囊和LPS的合成。我们的总体目标是确定控制开关从一个持久的，表面附着的状态，作为一个有毒的状态，能够破坏微生物宿主的稳态的调节途径。本申请中提出的研究具有重要意义，因为了解表面性质变化的控制是了解这种真菌转化为有毒病原体的重要环节。作为这些研究的结果，我们将表征控制表面聚糖（关键毒力决定因素）合成的调控机制。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。我们的结果可能会导致 涉及开发用于调节这种口腔病原体的生物膜形成的新的治疗策略。

 DESCRIPTION (provided by applicant): Porphyromonas gingivalis (Pg) is a Gram-negative anaerobe, strongly implicated in the etiology of adult periodontal disease. This research will increase our understanding of the molecular mechanisms that control synthesis of Pg cell surface glycans, and determine how changes in synthesis relate to biofilm persistence and pathogenicity. Our overarching model is that the biofilm state acts as a reservoir of bacteria, while capsule synthesis is linked to a transition to virulence and disruption of homeostasis. We have discovered that DNABII family members in Pg (HU PG0121 and HU PG1258) are involved in controlling synthesis of this surface polysaccharide. DNABII proteins are members of the Nucleoid Associated Proteins (NAPs), a class of proteins that possess multiple functions in maintaining the structure and function of DNA and RNA and are known to be critical for regulation of cell metabolism, the response to environmental perturbations, and in controlling the transition to and from a quiescent state. We have also identified an antisense RNA encoded in the 5'-end of the capsule locus (PG0104-PG0121) within a large 77bp inverted repeat (77bpIR) element. Deletion or over- expression of the region encoding this asRNA alters the synthesis of both LPS and K-antigen capsule. Our working model is that DNABII proteins interact with this asRNA and control expression of both the sense and antisense transcripts in this region. We have designated the asRNA asSuGR, for antisense Surface Glycan Regulator. The central hypothesis of this project is that HU PG0121 and HU PG1258 are key NAPs that play a fundamental role in modulating Pg pathogenicity. In these studies we will determine how these proteins and the 77bpIR element control synthesis of capsule and LPS. Our overall goal is to identify regulatory pathways that control the switch from a persistent, surface-attached state as a commensal to a virulent state capable of disrupting microbe-host homeostasis. 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 commensal makes to a virulent pathogen. As an outcome of these studies, we will have characterized regulatory mechanisms that control the synthesis of surface glycans, key virulence determinants. 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.