Investigating SloR virulence gene metalloregulation in Streptococcus mutans

项目摘要/摘要 变形链球菌引起的龋病在发达国家和发展中国家仍然是一个主要问题， 根据世界卫生组织的数据，这影响了全球60%-90%的儿童(63)。尽管 年普遍的饮水加氟和旨在改善口腔健康的教育方案的实施 在美国和国外，最近的报告显示，在患病率或严重性方面没有显著改善 乳牙期龋病()。此外，近100%的成年人患有或曾经患过龋齿。 恒牙，为世界估计的牙科治疗直接成本贡献了2980亿美元 2010年(31岁，，65岁)。 变形链球菌在口腔中的存活和致龋性直接关系到 基本金属离子，特别是铁和锰的有效性和迁移(11、12、48、55)。在现在 申请拨款后，我们提出了一种减轻龋齿的新方法，该方法的核心是研究毒力 变形链球菌金属调节蛋白的基因调控。在之前的资助期限内，我们确认 可持续水平下对变形链球菌金属离子转运基因和毒力因子的依赖盐抑制 锰是可以获得的(例如在用餐时)，当金属离子变得有限时，这种抑制作用就会丧失 (例如在两餐之间)。这些观察结果使我们建议对Slo进行修改，使其成为 结构性抑制，不管外源锰的有效性如何，都可以显着减弱变形链球菌 毒力基因的表达，阻碍了龋病的发生。此应用程序旨在解决这一问题 假说通过用分子阐明变形链霉菌中SLOR激活和DNA结合的结构基础， 生物化学和下一代测序方法。这项拟议的研究具有重要意义，因为它可以 加深对变形链球菌中金属离子动态平衡的了解，并为生长中的变形链球菌提供支持 涉及细菌金属离子摄取/转运调节剂作为关键治疗靶点的证据(1，4，8，35，37， 40、43)。此外，这些研究还可以揭示变形链球菌内在调节能力的机制。 毒力基因在人类口腔中的表达，其中金属离子的有效性、酸性pH和 氧化应激是其固有的生物膜生活方式的一部分。

PROJECT SUMMARY/ABSTRACT Streptococcus mutans-induced caries formation continues to be a major problem in developed and developing nations, which according to the World Health Organization, impacts 60-90% of children worldwide (63). Despite widespread water fluoridation and the implementation of educational programs aimed at improving oral health in the United States and abroad, recent reports reveal no significant improvement in the prevalence or severity of caries in the primary dentition (64). In addition, nearly 100% of adults either have or have had caries in their permanent teeth, contributing to the world's estimated direct costs for dental treatment that totaled $298 billion in 2010 (31, 64, 65). The survival and cariogenic potential of S. mutans in the human oral cavity is directly related to the availability and transport of essential metal ions, particularly iron and manganese (11, 12, 48, 55). In the present grant application, we profess a novel approach to alleviating tooth decay that is centered on investigating virulence gene regulation by the S. mutans SloR metalloregulatory protein. During the previous grant term, we confirmed SloR-dependent repression of S. mutans metal ion transport genes and virulence factors when sustainable levels of manganese are achieved (such as during a mealtime), and loss of this repression when metal ions become limiting (such as between meals). These observations led us to propose that modifications to SloR that render it constitutively repressive regardless of exogenous manganese availability can significantly attenuate S. mutans virulence gene expression and impede the process of cariogenesis. This application sets out to address this hypothesis by elucidating the structural basis for SloR activation and DNA binding in S. mutans using molecular, biochemical, and next-generation sequencing approaches. The proposed research is highly significant because it can lead to an improved understanding of metal ion homeostasis in S. mutans and lend support to the growing body of evidence that implicates regulators of bacterial metal ion uptake/transport as key therapeutic targets (1, 4, 8, 35, 37, 40, 43). Moreover, these studies can reveal the mechanisms that underlie the inherent ability of S. mutans to regulate virulence gene expression in the human mouth where significant changes in metal ion availability, acid pH and oxidative stress are part of its obligate biofilm lifestyle.