Role of Lrg pyruvate uptake system in Streptococcus mutans environmental adaptation

变形链球菌有效和快速地适应变化的环境的能力是一个重要的因素。 生物体持久性和致龋性的基本要素。在过去的融资中 我们的R 01赠款期间，我们发现，S。变形杆菌LrgAB系统，假设介导细胞 死亡和裂解与它的伴侣蛋白CidAB，功能作为一个固定相丙酮酸摄取系统 它的活性受到细菌细胞外和细胞内 代谢状态丙酮酸盐指导生长和能量产生的关键代谢通量，并迅速 在营养限制时作为溢流代谢物再循环到细胞中。的群体分布 lrgAB在稳定期的表达也呈现双峰特征，表明丙酮酸 摄取可能限于稳定期细胞的表达lrgAB的亚群。因此本 更新建议测试丙酮酸可能启动细胞和/或代谢反应的假设 通过LrgAB来处理不利条件，从而为 细胞亚群，以克服有限的资源和环境波动，经历了 口腔，从而促进生物膜群落的恢复力。这一假设将是 通过解剖S.关键环境参数的变异，如外部 丙酮酸和氧，关键的lrgAB的表达和功能，在背景下， 生物化学、转录组学和代谢组学过程。事实上， 微生物组参与LRG对环境线索的反应也对LRG的产生有深远的影响。 微生物动态环境对lrg介导表型的影响。研究联合国系统的贡献 LRG系统对复杂环境信号的整合调控网络 S.变形菌毒力和体内平衡将按照以下目标进行：目标1 通过lrgAB表达和响应关键的环境调节来解决代谢协调问题。 组分，外部丙酮酸盐和氧气，在细菌群落的背景下和生长期间 相变（靶向代谢组学和转录组学）。由于动态调节 丙酮酸摄取主要由Plrg激活驱动，目标2解决了lrgAB启动子如何被激活的问题。 差异激活响应细胞的外部和内部代谢状态。为此我们 检查CcpA、CodY和LytT在lrgAB启动子上的潜在相互作用， LytST通过其感测外部丙酮酸并随后激活lrgAB启动子。目标3 检验了分类组成及其代谢活动可能塑造当地环境的假设。 环境，并影响以植物为媒介的群落发育。中变形 口腔，通过使用含有口腔细菌的离体唾液生物膜模型。

The ability of Streptococcus mutans to efficiently and rapidly adjust to the changing environment is an essential element of the persistence and cariogenicity of the organism. During the previous funding period of our R01 grant, we revealed that the S. mutans LrgAB system, hypothesized to mediate cell death and lysis with its partner proteins CidAB, functions as a stationary-phase pyruvate uptake system and its activity is tightly regulated in response to both the bacteria’s extracellular and intracellular metabolic status. Pyruvate directs key metabolic fluxes for growth and energy generation, and is rapidly recycled into the cell upon nutrient limitation as an overflow metabolite. The population distribution of lrgAB expression at stationary phase also takes on a bimodal character, suggesting that pyruvate uptake may be limited to a lrgAB-expressing subpopulation of stationary phase cells. Therefore, this renewal proposal tests the hypothesis that pyruvate may initiate a cellular and/or metabolic response through LrgAB to deal with unfavorable conditions, consequently providing a selective advantage to a subpopulation of cells to overcome the limited resources and environmental fluctuations, experienced in the oral cavity, consequently promoting the resilience of a biofilm community. This hypothesis will be tested by dissecting the response of S. mutans to key environmental parameters such as external pyruvate and oxygen, critical for lrgAB expression and function, in the context of underlying biochemical, transcriptomic, and metabolomic processes. The fact that diverse members of the microbiome engage in the response of lrg to environmental cues also has profound implications for the effect of microbially dynamic environments in lrg-mediated phenotypes. Study of the contribution of the Lrg system to the integration of complex environmental signals into the regulatory networks modulating S. mutans virulence and homeostasis will be undertaken as described in the following aims: Aim 1 addresses the metabolic coordination by lrgAB expression and in response to key environmental components, external pyruvate and oxygen, in the context of bacterial community and during growth phase transitions (targeted metabolomics and transcriptomics). Given that the dynamic regulation of pyruvate uptake is primarily driven by Plrg activation, Aim 2 addresses how the lrgAB promoter is differentially activated in response to the cell’s external- and internal metabolic status. For this, we examine the potential interplays among CcpA, CodY, and LytT on the lrgAB promoter, and the process by which LytST senses external pyruvate and subsequently activates the lrgAB promoter. And Aim 3 tests the hypothesis that taxonomic composition and their metabolic activity may shape local environment, and have an effect on the pyruvate-mediated community development of S. mutans in oral cavity, by using an ex vivo saliva biofilm model containing oral commensal bacteria.