Characterization of a unique two-component system in streptococci

链球菌独特的双组分系统的表征

• 批准号: 8508912
• 负责人: Indranil Biswas
• 金额: $ 36.24万
• 依托单位: UNIVERSITY OF KANSAS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-11 至 2017-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8508912
• 关键词: Adult; Affect; Animal Model; Animals; Antibiotics; Bacillus (bacterium); Bacillus subtilis; Bacitracin; Bacteria; Binding Proteins; Binding Sites; Biochemical; Biological Assay; Biological Models; Cell Wall; Chemicals; Child; Communities; Competence; DNA Binding; DNA Binding Domain; DNA Sequence; Dental Plaque; Dental caries; Developed Countries; Development; Disease; Endocarditis; Environment; Expenditure; Family; Gene Expression; Gene Expression Regulation; Genes; Genetic; Genome; Genus staphylococcus; Goals; Growth; Human; Infective endocarditis; Investigation; Lead; Lipids; Mediating; Membrane; Methods; Microbial Biofilms; Modeling; Molecular; Oral; Oral cavity; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Production; Proteins; Reporter; Research Design; Role; Schools; Signal Pathway; Signal Transduction; Signal Transduction Pathway; Staphylococcus aureus; Stimulus; Streptococcus; Streptococcus Group B; Streptococcus mutans; System; Testing; United States; acid stress; bacteriocin; base; design; environmental flux; extracellular; global health; glucan-binding protein; in vivo; novel; novel therapeutics; pathogen; response; sensor; stress tolerance; tooth surface

DESCRIPTION (provided by applicant): Bacteria have many two-component signal-transduction systems (TCSs) that respond to specific environmental signals by altering the phosphorylated state of a response regulator. Although these systems are presumed to form an intricate signal network, the detailed mechanism of how they interact with each other remains largely unexplained. In this application, we will use Streptococcus mutans as a model organism to study a novel signaling pathway in bacteria. S. mutans is considered to be the primary etiological agent of dental caries and sometimes in infective endocarditis. This pathogen colonizes the oral cavity by formation of multispecies biofilm and has developed a variety of mechanisms to adapt and to flourish in the hostile environment of the oral cavity. We found that one particular TCS, LiaFSR, which encodes an extra protein (LiaF) in addition to the sensor kinase (LiaS) and the response regulator (LiaR), regulates the expression of gbpC that encodes a glucan-binding-protein necessary for biofilm formation and the onset of endocarditis. We also found that LiaFSR is necessary for the production of mutacin, a bacteriocin, to suppress the growth of other competitor bacteria present in the biofilm community. A recent microarray study revealed that 174 genes, ~9% of the genome, are regulated by this TCS. In Bacillus and Staphylococcus, this TCS is involved in sensing cell wall damage caused by various antibiotics, particularly those antibiotics that interfere with the lipid- II cycle. However, the signals sensedby this TCS and the molecular mechanism of signal transduction in streptococci are yet to be identified. A puzzling question is how LiaS and LiaR regulate target gene expression in S. mutans, since inactivation of LiaR does not produce, in many cases, any noticeable phenotypes. In this application, based on our preliminary results, we propose a model to explain how LiaS and LiaR may participate in signal transduction. We also propose a possible role for LiaF in LiaSR mediated gene regulation. Specific Aims 1 and 2 are designed to test our hypothesis to determine the mechanisms by which LiaS and LiaF participate in signal transduction. The goal of Aim 3 is to understand the molecular mechanism of DNA binding by LiaR. Upon completion, we hope to determine the cellular role of the LiaFSR that may lead to greater means of controlling this pathogen. This investigation will also promote our overall understanding of the molecular mechanisms of gene regulation and signal transduction in S. mutans and other related pathogens such as group A- and group B- streptococcus.

描述（由申请人提供）：细菌具有许多二元信号转导系统（TCS），它们通过改变响应调节剂的磷酸化状态来响应特定的环境信号。尽管这些系统被认为形成了一个复杂的信号网络，但它们如何相互作用的详细机制在很大程度上仍然无法解释。在此应用中，我们将使用变形链球菌作为模型生物来研究细菌中的新型信号传导途径。变形链球菌被认为是龋齿的主要病原体，有时也是感染性心内膜炎的主要病原体。这种病原体通过形成多物种生物膜在口腔中定殖，并已发展出多种机制来适应口腔的恶劣环境并在其中繁衍生息。我们发现一种特殊的TCS，LiaFSR，除了传感器激酶（LiaS）和反应调节器（LiaR）之外还编码一种额外的蛋白质（LiaF），调节gbpC的表达，gbpC编码生物膜必需的葡聚糖结合蛋白心内膜炎的形成和发作。我们还发现，LiaFSR 对于产生突变蛋白（一种细菌素）是必要的，以抑制生物膜群落中存在的其他竞争细菌的生长。最近的一项微阵列研究表明，174 个基因（约占基因组的 9%）受该 TCS 调节。在芽孢杆菌和葡萄球菌中，这种 TCS 参与感知各种抗生素引起的细胞壁损伤，特别是那些干扰脂质 II 循环的抗生素。然而，这种 TCS 感知的信号以及链球菌信号转导的分子机制尚未确定。一个令人费解的问题是 LiaS 和 LiaR 如何调节变形链球菌中的靶基因表达，因为在许多情况下，LiaR 失活不会产生任何明显的表型。在此应用中，根据我们的初步结果，我们提出了一个模型来解释 LiaS 和 LiaR 如何参与信号转导。我们还提出了 LiaF 在 LiaSR 介导的基因调控中的可能作用。具体目标 1 和 2 旨在检验我们的假设，以确定 LiaS 和 LiaF 参与信号转导的机制。目标 3 的目标是了解 LiaR 结合 DNA 的分子机制。完成后，我们希望确定 LiaFSR 的细胞作用，这可能会导致更好的方法来控制这种病原体。这项研究还将促进我们对变形链球菌和其他相关病原体（例如 A 组和 B 组链球菌）基因调控和信号转导的分子机制的全面了解。