VIRULENCE REGULATION IN STREPTOCOCCUS PYOGENES

20世纪80年代中期至后期，S见证了中国经济的急剧增长 风湿热和其他严重侵袭性疾病的发病率 由革兰氏阳性杆菌化脓性链球菌。这样做的原因是 增长是未知的，这在很大程度上反映了我们的贫困 对化脓性链球菌和化脓性链球菌之间发生的分子事件的理解 宿主细胞在感染期间，以及缺乏先进的技术来 这种生物体的分子遗传学分析。开始解决这些问题 问题，我感兴趣的是描述最初的遭遇 一种寄主细胞和化脓性链球菌的分子细节和发育中 促进这一分析的技术。我最近发现了蛋白质 F，一种链球菌纤维连接蛋白结合蛋白，是一种粘附素 某些上皮细胞群。编码基因的表达 蛋白F(PrtF)通过两条独立的途径调节：一条涉及 氧通过一种信号机制感知超氧化物(O2-)，而 二是利用调控基因rofA。后一种途径是 在结构性表达PrtF的菌株中发现(即在 没有02信号)，显然是由于表达异常所致 RofA的。 PrtF调控的进一步表征代表了一个重要的 有机会深入了解细菌、环境 和宿主因素对链球菌/宿主的动态影响 细胞相互作用。这项提案的目标也是开发几个 鉴定玉米赤霉菌毒力和调控基因的新技术 化脓性链球菌。Tn916和Tn4001的新型衍生物将被构建和 用于确定构成表达表型是否是结果 RofA本身的突变，或者驻留在另一个基因中。此外，由于 我构建了超氧化物表达异常的突变体 在PrtF的表达中，超氧化物歧化酶(SOD)也出现异常，我会发展 用遗传策略来检验这样一种假设：一个氧气感测全球 调控系统在链球菌/宿主细胞相互作用中起关键作用 通过鉴定调控PrtF和PrtF表达的基因 草皮。因为O2-和rofA确实调节prtF以及蛋白F的表达 需要非典型的培养条件，鉴定其他rofA和O2- 受调控的基因可能会导致识别新的潜力 毒力因素。最后，由于rofA可能在Signal中起作用 转导，rofA的几个潜在的环境信号将是 进行评估，以深入了解ROFA的S对 发病机制。

The mid- to late- 1980's were witness to a dramatic increase in the incidence of rheumatic fever and other severe and invasive diseases caused by the gram positive bacterium Streptococcus pyogenes. The reason for this increase is unknown, which to a large extent, reflects our poor understanding of the molecular events that occur between S. pyogenes and host cells during infection and a lack of sophisticated techniques for the molecular genetic analysis of this organism. To begin to address these problems, I am interested in characterizing the initial encounter between a host cell and S. pyogenes in molecular detail and in developing techniques to facilitate this analysis. I have recently identified protein F, a streptococcal fibronectin-binding protein that is an adhesin for certain epithelial cell populations. Expression of the gene which encodes protein F (prtF) is regulated via two independent pathways: One involves oxygen via a signaling mechanism that senses superoxide (O2-) while the second utilizes the regulatory gene rofA. The latter pathway was discovered in a strain which expresses prtF constitutively (i.e. in the absence of an 02- signal), apparently as a result of aberrant expression of rofA. Further characterization of the regulation of prtF represents an important opportunity to gain considerable insight into the bacterial, environmental and host factors which contribute to the dynamics of streptococcal/host cell interaction. It is also a goal of this proposal to develop several new techniques for the identification of virulence and regulatory genes in S. pyogenes. Novel derivatives of Tn916 and Tn4001 will be constructed and used to determine if the constitutive expression phenotype is the result of a mutation in rofA itself, or resident in another gene. Also, since mutants I have constructed that are aberrant in expression of superoxide dismutase (Sod) are also aberrant in expression of prtF, I will develop genetic strategies to test the hypothesis that an O2- sensing global regulatory system plays a key role in streptococcal/host cell interaction through the identification of genes which regulate expression of prtF and sod. Since O2- and rofA do regulate prtF, and expression of protein F also requires atypical culture conditions, identification of other rofA and O2- regulated genes will likely result in the identification of new potential virulence factors. Finally, since rofA likely plays a role in signal transduction, several potential environmental signals for rofA will be evaluated in order to gain insight into rofA 's contribution to pathogenesis.