Investigating Membrane Alterations as a Mechanism of Acid Tolerance in Cariogenic Bacteria

项目摘要/摘要 龋齿是全球最常见的慢性传染病，由酸性物质的形成引起。 在牙齿表面产生细菌生物膜，使牙齿表面脱矿并破坏保护底层 釉质屏障。尽管氟化物治疗(当代防龋标准)的疗效是 有据可查的是，目前这种疾病的流行情况清楚地表明，仅有氟化物不足以 在许多情况下预防龋齿。因此，增加了对疾病发病机制的认识和探索 新的预防战略是值得关注的目标。不管涉及的微生物分类群是什么， 细菌耐酸性是龋病发生中不可缺少的因素。已知的龋病病原体 变形链球菌增加其质膜不饱和脂肪酸(UFAs)的比例 对环境酸化的反应--耐酸性和毒性所需的适应。初步 数据表明，其他几个革兰氏阳性口腔分类群，包括与龋齿相关的种类，乳杆菌 干酪，以类似的方式对其膜进行改性，以响应环境酸化。这项建议 回答了这些观察提出的一些目前尚未得到回答的问题。目标1和2 拟议的研究将确定口腔微生物群对酸胁迫的这种反应的范围。 分类群或在群落环境中。这项提案的目标3将阐明这些不饱和脂肪酸是如何抵御酸- 介入性损害。这些目标将使用生物信息学工具、基础分子微生物学、 一种与生态相关的复杂的体外口腔生物膜模型，以及质谱学/脂质组学。成功 拟议研究的完成将回答有关龋齿发病机制的相关问题。 物种设置，并可能打开研究新的防龋剂的大门，虽然 以嗜酸菌为靶标，功能与变形链球菌的存在和丰度无关。这位候选人是Dr。 乔纳森·贝克对龋齿的微生物学有着长期的兴趣。在K99完成后 (指导)这个奖项的阶段，他的目标是成为一所领先的研究型大学的独立PI，在那里 他计划继续研究细菌对其细胞膜的修饰以对抗 环境压力，同时利用获得的数据开发新的治疗方法。A资助K99/R00 提案将允许贝克博士发展完成拟议研究(培训)所需的技能 质谱学/脂质组学)，随后成为一名独立的研究科学家(接受教学培训 讲课、指导和恩赐精神)。贝克博士的导师和环境：Karen Nelson博士(J.Craig Venter Institute)、Anna Edlund(J.Craig Venter Institute/加州大学圣地亚哥分校)、Pieter Dorrestein(加州大学圣地亚哥分校)、Victor 尼泽特(加州大学圣地亚哥分校)和小罗伯特·奎维(罗切斯特大学医学和牙科学院) 经过精心挑选，提供高质量、多样化的科学和合作支持，以及最先进的 设施，以确保成功完成这项研究计划和拟议的职业发展目标。

Project Summary/Abstract Dental caries is the most common chronic infectious disease globally and is caused by the formation of acid- producing bacterial biofilms on the tooth surface, which demineralize and destroy the protective underlying enamel barrier. Although the efficacy of fluoride treatments (the contemporary standard in caries prevention) is well-documented, the current prevalence of the disease clearly illustrates that fluoride alone is insufficient to prevent caries in many situations. Therefore, increased understanding of disease pathogenesis and exploration of novel preventative strategies are objectives worthy of attention. Regardless of the microbial taxa involved, bacterial acid-tolerance is an indispensable factor in caries pathogenesis. The known caries pathogen Streptococcus mutans increases the proportion of unsaturated fatty acids (UFAs) in its plasma membrane in response to environmental acidification—an adaptation required for acid-tolerance and virulence. Preliminary data indicates that several other Gram-positive oral taxa, including the caries-associated species, Lactobacillus casei, modify their membranes in a similar manner in response to environmental acidification. This proposal addresses a number of currently unanswered questions raised by these observations. Aims 1 and 2 of the proposed research will determine the scope of this response to acid stress across the oral microbiome, in single taxa or in a community setting. Aim 3 of this proposal will elucidate how these UFAs are protective against acid- mediated damage. These aims will be accomplished using bioinformatics tools, basic molecular microbiology, an ecologically-relevant and complex in vitro oral biofilm model, and mass spectrometry/lipidomics. Successful completion of the proposed research will answer pertinent questions regarding caries pathogenesis in a multi- species setting and is likely to open the door to investigation of novel anti-caries therapeutics which, while targeting acidophiles, function regardless of the presence and abundance of S. mutans. The candidate, Dr. Jonathon Baker, has a longstanding interest in the microbiology of dental caries. Upon completion of the K99 (mentored) phase of this award, his goal is to become an independent PI at a leading research university, where he plans to continue research on the modifications that bacteria make to their membranes to combat environmental stresses, while leveraging acquired data to develop novel therapeutics. A funded K99/R00 proposal will allow Dr. Baker to develop skills necessary to both complete the proposed research (training in mass spectrometry/lipidomics) and subsequently become an independent research scientist (training in didactic lecturing, mentoring, and grantsmanship). Dr. Baker’s mentors and environment: Drs. Karen Nelson (J. Craig Venter Institute), Anna Edlund (J. Craig Venter Institute/UC San Diego), Pieter Dorrestein (UC San Diego), Victor Nizet (UC San Diego) and Robert Quivey, Jr. (University of Rochester School of Medicine and Dentistry) have been carefully selected to provide high-quality, diverse scientific and collegial support, as well as state-of-the-art facilities, to ensure successful completion of this research program and the proposed career development goals.