Investigating SloR virulence gene metalloregulation in Streptococcus mutans

项目总结/摘要 变形链球菌引起的龋齿形成仍然是发达国家和发展中国家的主要问题， 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 广泛的水氟化和实施旨在改善口腔健康的教育计划， 在美国和国外，最近的报告显示， 乳牙列龋齿（64）。此外，近100%的成年人在他们的生活中患有或曾经患有龋齿。 据估计，2010年全世界牙科治疗的直接费用总计2980亿美元， 2010年（31、64、65）。 S.人类口腔中的变形菌与 必需金属离子的可用性和运输，特别是铁和锰（11，12，48，55）。本 在一份拨款申请中，我们提出了一种以研究毒性为中心的减轻蛀牙的新方法。 S.变形杆菌SloR金属调节蛋白。在上一个资助期内，我们确认 SloR依赖的S.变异金属离子转运基因和毒力因子， 锰达到（如在进餐时间），并失去这种抑制时，金属离子成为限制 (such在两餐之间）。这些观察使我们提出，对SloR进行修改， 无论外源锰是否有效，组成型抑制都能显著抑制S.变形 毒力基因的表达，并阻止龋的发生过程。本申请旨在解决这一问题 通过阐明SloR激活和S.使用分子， 生物化学和下一代测序方法。这项研究非常重要，因为它可以 从而提高对S.变种人，并支持越来越多的 有证据表明细菌金属离子摄取/转运的调节剂是关键的治疗靶点（1，4，8，35，37， 40、43）。此外，这些研究可以揭示S.变异体来调节 在人类口腔中的毒力基因表达，其中金属离子可用性、酸性pH和 氧化应激是其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.