Modulation of Virulence Determinants Contributing to Gonococcal Pathogenesis

描述(申请人提供)：淋病奈瑟菌是一种革兰氏阴性、严格的人类病原体，可引起性传播疾病淋病。全球淋病感染的发病率(估计每年超过6000万例)以及这种细菌对大多数用于治疗感染的抗生素产生抗药性的能力，使其成为全球公共卫生问题。淋球菌感染通常始于粘膜表面，需要细菌与上皮细胞相互作用。淋球菌附着在粘膜表面的主要介质之一是IV型菌毛(TFP)，它是从细菌延伸出来的菌毛聚合物，与上皮细胞上的受体相互作用。本研究的目的是明确控制淋病奈瑟菌TFP表达的调控机制。编码主要菌毛蛋白亚基的基因既有时相变异，也有抗原变异。我们最近发现了一种称为PssR(菌毛分泌系统抑制蛋白)的转录调控因子，它负调控菌毛生物合成操纵子(PilMNOPQ)和差异转录的青霉素结合蛋白1(PONA)，以及编码参与菌毛蛋白抗原变异的蛋白的基因(RdgC)。此外，我们的初步数据表明，PssR对淋球菌基因表达的调节可能有助于调节细菌对天然宿主防御机制的敏感性，特别是被认为在宿主抵抗感染中起重要作用的阳离子抗菌肽。为了更好地定义PssR的调节特性，我们将确定其DNA结合和转录调节特性(特定目标1)。我们还将确定与毒力和抗菌素耐药性相关的Pss R缺失或过度表达的表型效应(特定目标2)。由于TFP对生殖道粘膜表面感染的启动至关重要，对TFP和/或其他毒力决定因素的调控研究将促进我们对淋球菌如何调控毒力决定因素及其调控在致病机制中的作用的了解。

DESCRIPTION (provided by applicant): Neisseria gonorrhoeae is a Gram-negative, strict human pathogen that causes the sexually transmitted disease, gonorrhea. The incidence of gonorrhea infections worldwide (estimated at over 60 million cases a year) and the ability of the bacteria to become resistant to most antibiotics used to treat infections makes it a global public health concern. Gonoccocal infections are usually initiated on mucosal surfaces, and require interaction of the bacteria with epithelial cells. One of the primary mediators of gonococcal attachment to mucosal surfaces is the Type IV pil (Tfp), which are polymers of pilin that extend from the bacteria and interact with receptors on epithelial cells. The goal of the proposed research is to define the regulatory mechanisms that control expression of Tfp in N. gonorrhoeae. The gene encoding the major pilin subunit (PilE) is subject to both phase and antigenic variation. We recently have identified a transcriptional regulator termed PssR (Pilus secretion system Represser Protein) that negatively regulates the pilus biosynthesis operon (pilMNOPQ) and the divergently transcribed penicillin-binding protein 1 (ponA) as well as a gene (rdgC) that encodes a protein involved in pilin antigenic variation. Moreover, our preliminary data indicate that PssR regulation of gene expression in N. gonorrhoeae may serve to modulate levels of bacterial susceptibility to innate host defense mechanisms, in particular the cationic antibacterial peptides that are postulated to be important in host resistance to infection. In order to better define the regulatory properties of PssR, we will determine its DNA-binding and transcriptional regulatory properties (Specific Aim 1). We will also determine the phenotypic effects of loss or over-expression of PssR relating to virulence and resistance to antimicrobials (Specific Aim 2). Since Tfp are critical for initiation of infection on mucosal surfaces of the genitourinary tract, studies on regulation of Tfp and/or other virulence determinants will advance our knowledge of how gonococci regulate virulence determinants and how their regulation contributes to pathogenesis.