Regulatory Mechanisms Controlling Expression of P. gingivalis Surface Structures

 描述(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。这项研究将加深我们对PG细胞表面多糖合成的分子机制的理解，并确定合成的变化与生物被膜持久性和致病性的关系。我们的总体模型是，生物膜状态充当细菌的储存库，而胶囊合成与毒力和动态平衡的破坏有关。我们发现PG(Hu PG0121和Hu PG1258)中的DNABII家族成员参与了该表面多糖的合成调控。DNABII蛋白是类核相关蛋白(NAPS)的成员，NAPS是一类具有多种功能的蛋白质，在维持DNA和RNA的结构和功能方面具有多种功能，在调节细胞代谢、对环境扰动的反应以及控制从静止状态向静止状态的转变方面发挥着至关重要的作用。我们还在一个77bp的反向重复序列(77bpIR)中发现了一个编码在被膜基因5‘端(PG0104-PG0121)的反义RNA。编码该asRNA的区域的缺失或过度表达改变了内毒素和K抗原被膜的合成。我们的工作模型是DNABII蛋白与这个asRNA相互作用，并控制该区域正义和反义转录本的表达。我们将asRNA命名为SuGR，即反义表面多糖调节因子。该项目的中心假设是，Hu PG0121和Hu PG1258是调控PG致病性的关键NAP。在这些研究中，我们将确定这些蛋白质和77bpIR元件如何控制胶囊和内毒素的合成。我们的总体目标是确定控制从持续的、表面附着的共生状态切换到能够破坏微生物-宿主动态平衡的毒力状态的调控途径。在这项申请中提出的研究具有重要意义，因为了解表面属性变化的控制是理解这种共生关系向致病毒力病原体转变的关键环节。作为这些研究的结果，我们将描述控制表面多糖合成的调控机制，这是毒力的关键决定因素。这些信息将有助于更好地理解调控网络，这些网络要么引导牙龈假单胞菌成为一种毒力病原体，要么继续保持低调并持续存在。我们的结果可能会领先于 开发新的治疗策略来调节这种口腔病原体的生物被膜形成。

 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.