Epigenetics of the human gut microbiome

项目摘要 拟议的研究解决了细菌表观遗传学在人类肠道微生物组中的作用及其对人类肠道微生物的影响。 与健康和疾病的机械联系。几乎所有的微生物都有DNA修饰--表观基因组， 调节基因表达和免疫系统功能的遗传标记，最常见于限制性免疫系统， 修改（RM）。虽然自2005年以来已经知道了充分表征的基于DNA甲基化的RM系统， 20世纪70年代，现在有超过30种DNA修饰在细菌和噬菌体中定义，包括我们最近的 硫代磷酸酯（PT）和7-脱氮鸟嘌呤修饰的发现。DNA修饰也调节基因 表达，如DNA腺嘌呤甲基转移酶，DAM，和细胞周期调节甲基化酶，CcrM， 其控制影响毒力和噬菌体抗性的遗传基因表达，以及非- 遗传基因表达虽然这些细菌表观遗传学的例子与人类疾病有关， 关于DNA修饰如何决定或影响肠道中的微生物种群， 影响单个微生物物种的行为或生存，或者是否存在 特定微生物组表观遗传学与人类健康和疾病。在这里，我们使用创新的分析， 信息学和基因组学工具来探索这些问题，最初的重点是细菌DNA 在约15%的人类肠道微生物中发现的修饰：PT修饰，其中具有氧化还原活性的S取代了具有氧化还原活性的S。 DNA骨架中的非键氧。拟议的研究是由广泛分布的 细菌病原体和细菌中的PT，PT对氧化的敏感性， 炎症，以及炎症对肠道微生物群的已知影响，所有这些都表明炎症 可能会改变含有PT的肠道微生物的平衡。然而，我们对微生物组几乎一无所知， 表观遗传学，更不用说哪些肠道细菌拥有氧化还原敏感的PT和其他表观遗传标记。我们现在 建议定义健康人体肠道中含PT细菌的景观，阐明其作用 肠道炎症期间微生物组中PT的变化，并在肠道中发现新的表观遗传标记 微生物组我们从定量PT和鉴定粪便DNA样本中含有PT的细菌开始， 健康捐赠者的广泛微生物组文库和从这些样品培养的约7000株菌株（dnd基因 占15%）。然后，我们测试了氧化还原敏感性PT影响发炎肠道中细菌适应性的想法， 定量来自炎性肠病的20-30个粪便样品中的PT水平和含PT细菌 (IBD)患者最后，我们将确定肠道微生物中新的DNA修饰，使用新技术， 在BML捐赠者和菌株的库存粪便样本中发现DNA标记，然后将它们与独特的 微生物组表型和与人类疾病的关联。该项目的意义在于， 含PT微生物在人类健康和疾病中的潜在作用，PT的潜在临床影响， 包含IBD的细菌，以及开发新的工具来发现新的微生物组表观遗传系统。

Project Summary The proposed studies address the role of bacterial epigenetics in the human gut microbiome and their mechanistic links to health and disease. Virtually all microbes possess DNA modifications – the epigenome -- inherited marks that regulate gene expression and function as immune systems, most commonly in restriction- modification (RM). While well-characterized DNA methylation-based RM systems have been known since the 1970s, there are now >30 DNA modifications defined in bacteria and bacteriophage, including our recent discovery of phosphorothioate (PT) and 7-deazaguanine modifications. DNA modifications also regulate gene expression, such as the DNA adenine methyltransferase, DAM, and cell cycle-regulated methylase, CcrM, which control heritable gene expression affecting virulence and bacteriophage resistance, as well as non- heritable gene expression. While these examples of bacterial epigenetics have links to human disease, we know little about how DNA modifications determine or affect microbial populations in the gut, how they affect the behavior or survival of individual microbial species, or if there is a relationship between specific microbiome epigenetics and human health and disease. Here we use innovative analytics, informatics, and genomics tools to explore these questions, with an initial focus on a bacterial DNA modification found in ~15% of human gut microbes: PT modifications, in which a redox-active S replaces a non-bonding oxygen in the DNA backbone. The proposed studies are driven by the widespread distribution of PTs in bacterial pathogens and commensals, the susceptibility of PTs to oxidation by chemical mediators of inflammation, and the known effects of inflammation on gut microbiota, all of which suggest that inflammation could alter the balance of PT-containing gut microbes. However, we know virtually nothing about microbiome epigenetics, much less which gut bacteria possess redox-sensitive PTs and other epigenetic marks. We now propose to define the landscape of PT-containing bacteria in the healthy human gut, elucidate the role of PTs in microbiome changes during gut inflammation, and discover new epigenetic marks in the gut microbiome. We start by quantifying PTs and identifying PT-containing bacteria in fecal DNA samples from healthy donors to the Broad Microbiome Library and in ~7000 strains cultured from these samples (dnd genes found in 15%). We then test the idea that redox-sensitive PTs affect bacterial fitness in the inflamed gut, quantifying PT levels and PT-containing bacteria in 20-30 fecal samples from inflammatory bowel disease (IBD) patients. Finally, we will identify new DNA modifications in gut microbes, using novel technologies to discover DNA marks in banked fecal samples from BML donors and strains, and then link them to unique microbiome phenotypes and associations with human disease. The significance of this project lies in the potential role for PT-containing microbes in human health and disease, the potential clinical impact of PT- containing bacteria on IBD, and the development of new tools to discover new microbiome epigenetic systems.