MECHANISMS OF VIRULENCE GENE REGULATION IN S. AUREUS

描述（改编自申请人的摘要）： 在过去50年的研究努力中，金黄色葡萄球菌仍然是一种 严重威胁人类健康。事实上，最近的报道分离与 对万古霉素敏感性降低表明 那辆多金黄色葡萄球菌可能会对目前可用的每种抗菌剂产生耐药性 剂因此，S.金黄色葡萄球菌对人类健康的威胁比 在抗生素使用前的任何时候的长期目标 研究人员的研究是开发新的抗葡萄球菌治疗药物， 阻止耐药菌株发展的药物。当前的提议是 重点研究了两个毒力基因的全局调控因子之间的相互作用 表达式：sar和agr。调查人员和其他人之前的工作表明， sar基因的产物SarA是一种转录因子， 激活AGR表达并导致生物体的毒力增强。 因为agr、sar和agr/sar突变体在动物模型中的毒力较低， 他们认为，SarA/agr相互作用是一种非常重要的机制， 葡萄球菌毒力的新型抑制剂的有前途的目标。重要的是， 由于SAR和AGR突变体生长正常，但毒性较低， 降低了进化压力，使其对这种类型的抑制剂产生耐药性， 与抑制生长的经典抗生素相比。此外还有 有报道说SAR和AGR突变体对现有的 抗微生物剂，包括甲氧西林。SarA/agr抑制剂 因此，相互作用对于增加 现有的药物。为了提供抑制剂开发的基础，他们将 首次揭示了SarA激活agr基因表达的机制。的 本研究的前三个具体目标是：1）定义cis 负责SarA激活agr基因的调控元件，2） 确定激活agr所需的SarA功能域 转录，3）确定SarA与agr调控蛋白的相互作用， 原子水平的元素。这些目标将通过以下方式实现： 诱变，体外和体内活性测定，X射线晶体学， 和原子力显微镜第四个具体目标，开始发展 靶向这些全局调节因子的抗葡萄球菌抑制剂， 目的是检验SarA-agr是新的靶点的假设。 抗葡萄球菌药物这种基础广泛的方法利用了 协调小组，每个成员都是其领域的专家。

DESCRIPTION (Adapted from the Applicant's Abstract): Despite intensive research efforts over the past 50 years, Staphylococcus aureus remains a serious threat to human health. In fact, recent reports of isolates with reduced susceptibility to vancomycin are indicative of the growing likelihood that S. aureus may become resistant to every currently available antimicrobial agent. Therefore, S. aureus represents a bigger threat to human health now than at any time since the pre-antibiotic area. The long-term goal of the investigators' research is to develop novel anti-staphylococcal therapeutic agents to stem the advance of drug-resistant strains. The current proposal is focused on the interaction of two globally-acting regulators of virulence gene expression: sar and agr. Previous work by the investigators and others indicate that the product of the sar gene, SarA, is a transcription factor that activates agr expression and leads to enhanced virulence of the organism. Because agr, sar and agr/sar mutants are less virulent in animal models of staphylococcal disease, they believe that the SarA/agr interaction is a very promising target for novel inhibitors of staphylococcal virulence. Importantly, since sar and agr mutants grow normally, but are less virulent, there should be reduced evolutionary pressure to become resistant to this type of inhibitor in comparison with classical antibiotics that inhibit growth. In addition, there are reports of increased sensitivity of sar and agr mutants to existing antimicrobial agents including methicillin. Inhibitors of the SarA/agr interaction may therefore be useful with respect to increasing the utility of existing drugs. To provide the foundation for inhibitor development, they will first reveal the mechanism by which SarA activates agr gene expression. The first three Specific Aims of the proposed research are: 1) to define the cis regulatory elements responsible for activation of the agr genes by SarA, 2) to define the functional domains of SarA required for activation of agr transcription, 3) to define the interaction of SarA with the agr regulatory elements at the atomic level. These aims will be accomplished by a combination of mutagenesis, in vitro and in vivo activity assays, x-ray crystallography, and atomic force microscopy. The fourth Specific Aim, to begin to develop anti-staphylococcal inhibitors that target these global regulatory factors, is intended to test the hypothesis that SarA-agr is a suitable target for novel anti-staphylococcal drugs. This broad-based approach takes advantage of a coordinated team, each member of which is an expert in his/her field.