VIRULENCE REGULATION IN STREPTOCOCCUS PYOGENES

20世纪80年代中后期， 风湿热和其他严重侵袭性疾病的发病率 由革兰氏阳性细菌化脓性链球菌感染其原因 增长情况不详，这在很大程度上反映了我们贫穷 了解发生在S.化脓性和 感染过程中的宿主细胞和缺乏复杂的技术， 分子遗传学分析开始解决这些问题 问题，我感兴趣的是描述之间的最初遭遇 宿主细胞和S.化脓性链球菌的分子细节和发展 技术，以促进这一分析。我最近发现了一种蛋白质 F，一种链球菌纤连蛋白结合蛋白，是一种粘附素， 某些上皮细胞群。表达的基因编码 蛋白F（prtF）通过两个独立的途径调节：一个涉及 氧通过信号机制，感觉超氧化物（O2-），而 二是利用调控基因rofA。后一种途径是 在组成型表达prtF的菌株中发现（即在 缺乏02-信号），显然是异常表达的结果 rofA的。 对prtF调控的进一步表征代表了一个重要的 有机会获得相当深入的细菌，环境 和宿主因子，其有助于链球菌/宿主的动力学 细胞相互作用本提案的另一个目标是制定若干 新技术用于鉴定毒力和调控基因， S.化脓将构建Tn 916和Tn 4001的新型衍生物， 用于确定组成型表达表型是否是 rofA自身的突变，或者存在于另一个基因中。此外，由于 我构建的突变体在超氧化物的表达中异常， SOD也有prtF表达异常，我将进一步研究 遗传策略来检验假设， 调节系统在链球菌/宿主细胞相互作用中起关键作用 通过鉴定调节prtF表达的基因， 该死。由于O2-和rofA确实调节prtF，并且蛋白F的表达也 需要非典型培养条件、鉴定其他rofA和O2- 受调控的基因可能会导致新的潜在的识别 毒力因子最后，由于rofA可能在信号中起作用， 转导，rofA的几个潜在的环境信号将被 评估，以了解rofA的贡献， 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.