Elucidating the regulation and spread of an integrative and conjugative element from Streptococcus mutans in the oral microbiome

项目摘要/摘要 微生物的进化是由水平基因转移(Hgt)主导的，这种转移普遍存在于细菌生物膜中。 比如牙菌斑。HGT通常由结合元件介导，可移动的遗传元件编码 将该元件从宿主(供体)细胞转移到受体细胞的机械，从而产生新的 细菌宿主。整合和共轭成分(ICE)似乎是最普遍的共轭成分 元素和一些中介不同细菌物种之间的遗传交换。冰在气候变化中起着至关重要的作用 毒力特征和抗生素耐药性在多重耐药病原体中的传播。冰块，或推定的 冰在口腔细菌中很普遍。变形链球菌是导致龋齿的主要病原体，它含有 一种没有特征的ICE TnSmu1。这项提议首次将TnSmu1描述为 HGT在这种关键的口腔病原体中。数据表明，TnSmu1是一个功能性的ICE：它可以从 宿主染色体并转移到受体细胞。TnSmu1的生理功能(S)及其驾驶能力 口腔中的HGT尚不清楚。这项研究验证了TnSmu1激活受宿主影响的假设 生理信号和TnSmu1在口腔链球菌中的存在可以提高口腔社区的存活率。 这项提议将阐明TnSmu1的调节和适应属性以及它转移到 口腔微生物群的其他成员。由变形链球菌编码的两个转录因子COVR和SLOR(即， 不是在TnSmu1中)，控制许多与龋病形成有关的毒力基因，并结合预测的调控 TnSmu1的区域。这项研究考察了这些因素是否将变形链球菌的致病属性与其在 HGT。这项建议将调查COVR和SLER的作用以及调节 他们关于TnSmu1的切除和转移。这项工作测试了TnSmu1在 不同的口腔菌斑群落，将自身和其他可移动的遗传元素转移到不同的口腔 细菌种类。它还将确定TnSmu1对宿主细胞的成本/收益，因为它的存在可能会影响S. 变种人在口腔中的健康。在这些研究结束时，这项工作将创造一个新的 了解口腔微生物群中变形链球菌的HGT、进化和致病机制。此外，这一点 这项工作将产生对许多缺乏强大遗传系统的口腔微生物进行基因操作的工具。 奖学金培训计划为研究员提供细菌遗传学方面的培训，同时利用 有宿主病原体相互作用的背景。格罗斯曼博士(赞助商)是一位著名的细菌专家 遗传学家和分子生物学家，作为教授有30年的指导经验，与许多 博士后实习生获得独立研究职位。本实验室的研究环境和 麻省理工学院内部的服务于解决所提出的研究的目标，并 帮助申请者发展为独立研究人员并长期担任学术教授。

Project Summary/Abstract Microbial evolution is dominated by horizontal gene transfer (HGT), which is prevalent in bacterial biofilms such as dental plaque. HGT is often mediated by conjugative elements, mobile genetic elements that encode machinery to transfer the element from a host (donor) cell to a recipient cell, thereby generating a new bacterial host. Integrative and conjugative elements (ICEs) appear to be the most prevalent type of conjugative element and some mediate genetic exchange between diverse bacterial species. ICEs play a critical role in the spread of virulence traits and antibiotic resistances within multidrug resistant pathogens. ICEs, or putative ICEs, are prevalent in oral bacteria. Streptococcus mutans, a major causative agent of dental caries, contains an uncharacterized ICE TnSmu1. This proposal undertakes the first characterization of TnSmu1 as a model of HGT within this critical oral pathogen. The data show that TnSmu1 is a functional ICE: It can excise from the host chromosome and transfer to recipient cells. The physiological function(s) of TnSmu1 and its ability to drive HGT in the oral cavity are unknown. This study tests the hypothesis that TnSmu1 activation is affected by host physiological signals and TnSmu1 presence in oral Streptococci allows increased survival in oral communities. This proposal will elucidate the regulation and fitness attributes of TnSmu1 and its ability to transfer to other members of the oral microbiome. Two transcription factors, CovR and SloR, encoded by S. mutans (i.e., not in TnSmu1), control many virulence genes involved in caries formation and bind the predicted regulatory region of TnSmu1. This study examines if these factors link the pathogenic attributes of S. mutans to its role in HGT. This proposal will investigate the role of CovR and SloR and the physiological conditions that regulate them on the excision and transfer of TnSmu1. This work tests the ability of TnSmu1 to spread within the diverse oral communities of dental plaque, transferring itself and other mobile genetic elements to different oral bacterial species. It will also define the cost/benefit of TnSmu1 to its host cells, as its presence may impact S. mutans fitness in the oral cavity. At the conclusion of these studies, this work will have created a new understanding of HGT, evolution, and pathogenesis of S. mutans within the oral microbiome. Additionally, this work will result in tools to genetically manipulate many oral microbes that lack robust genetic systems. The fellowship training plan provides the fellow with training in bacterial genetics while leveraging the fellow’s background with host pathogen interactions. Dr. Grossman (sponsor) is a renowned bacterial geneticist and molecular biologist that has >30 years of mentorship experience as a professor with many postdoctoral trainees obtaining independent research positions. The research environment in this lab and within the Massachusetts Institute of Technology serves to address the aims of the research proposed and to aid in the applicant’s development as an independent researcher and long term as an academic professor.