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

项目总结/摘要 水平基因转移（HGT）是微生物进化的主要方式，它普遍存在于细菌生物膜中 例如牙菌斑。HGT通常由接合元件介导，接合元件是编码HGT的移动的遗传元件。 将该元件从宿主（供体）细胞转移到受体细胞的机器，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类型 元件和一些介导不同细菌物种之间的遗传交换。ICE在以下方面发挥着关键作用： 在多重耐药病原体中传播毒力性状和抗生素耐药性。ICE或推定的 ICE在口腔细菌中普遍存在。变形链球菌是龋齿的主要致病菌， 未表征的ICE TnSmu 1。该提案首次将TnSmu 1表征为 HGT在这一关键的口腔病原体。数据显示TnSmu 1是一种功能性ICE：它可以从 宿主染色体并转移到受体细胞。TnSmu 1的生理功能及其驱动 口腔中的HGT未知。本研究验证了TnSmu 1激活受宿主影响的假设， 生理信号和TnSmu 1在口腔链球菌中的存在允许口腔群落中的存活增加。 该提案将阐明TnSmu 1的调节和适应性属性及其转移到 口腔微生物组的其他成员。S.变异体（即， 不存在于TnSmu 1中），控制许多参与龋齿形成的毒力基因，并结合预测的调控基因。 TnSmu 1的区域。本研究探讨这些因素是否与沙门氏菌的致病属性有关。它的作用， HGT该提案将研究CovR和SloR的作用以及调节细胞凋亡的生理条件。 他们对TnSmu 1的切除和转移。这项工作测试了TnSmu 1在细胞内传播的能力。 不同的口腔菌斑群落，将自身和其他移动的遗传因子转移到不同的口腔菌斑中， 细菌种类它还将定义TnSmu 1对其宿主细胞的成本/效益，因为它的存在可能影响S。 口腔中的变形菌在这些研究结束时，这项工作将创造一个新的 了解HGT、S.的进化和发病机制。口腔微生物组中的变形菌。而且这个 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遗传操作的工具。 研究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 宿主病原体相互作用的研究背景Grossman博士（申办方）是著名的细菌学家， 遗传学家和分子生物学家，拥有超过30年的指导经验，作为一个教授与许多 获得独立研究职位的博士后学员。这个实验室的研究环境 在马萨诸塞州技术研究所内的服务，以解决所提出的研究目标，并 帮助申请人发展为独立研究人员和长期学术教授。

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.