Understanding how heme and iron are metabolized by anaerobic commensal bacteria and host-microbiome communities

了解厌氧共生细菌和宿主微生物群落如何代谢血红素和铁

• 批准号: 10348775
• 负责人: Jennifer L DuBois
• 金额: $ 35.65万
• 依托单位: MONTANA STATE UNIVERSITY - BOZEMAN
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2026-02-28
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10348775
• 关键词: Aerobic; Anaerobic Bacteria; Anemia; Animals; Bacteria; Bacteroides thetaiotaomicron; Biochemistry; Cells; Chemicals; Clostridium; Coculture Techniques; Colitis; Collaborations; Colon; Colon Carcinoma; Communities; Culture Media; Development; Diet; Dietary Iron; Disease; Ecosystem; Enteral; Escherichia coli; Fermentation; Gastrointestinal tract structure; Generations; Genes; Gnotobiotic; Goals; Heme; Heme Iron; Human; Infection; Inflammation; Infrastructure; Iron; Iron deficiency anemia; Isotope Labeling; Knock-out; Knowledge; Lactobacillus casei rhamnosus; Meat; Mediating; Metabolic Pathway; Metabolism; Mus; Nutrition Disorders; Nutritional; Play; Population; Probiotics; Process; Proteome; Respiration; Role; Stable Isotope Labeling; Time; Walking; Work; absorption; base; catalyst; commensal bacteria; flasks; gene product; gut microbes; host microbiome; interest; iron deficiency; iron metabolism; member; microbial; microbiome; uptake

PROJECT SUMMARY Little is known about how bacteria prevalent in the digestive tract, most of which are anaerobes, take up and process the host’s dietary iron. How this activity influences the efficiency with which iron is absorbed by the host is also unclear. Closing this gap in the knowledge is of both fundamental and biomedical interest. Iron- deficiency and associated anemia are the most prevalent nutritional disorders worldwide, shared by nearly a third of the human population. At the same time, unmetabolized heme iron from red meat diets that remains in the colon has been associated with the development of diseases ranging from inflammation to colon cancer, with microbial activity postulated to play a key role. The long-term goal of this work is to understand how commensal bacteria commonly found in the healthy mammalian gut metabolize iron under the low/no O2 conditions that are prevalent in this ecosystem. The proposed work focuses our group’s knowledge and infrastructure – accrued over 15 years of studying aerobic heme/iron biochemistry at the level of the catalyst, cell, and ecosystem – on this ambitious long-term goal, which we have divided into two overlapping parts. First, we will examine how common gut microbes, most of which are anaerobic, heme auxotrophic bacteria (HAB), metabolize heme. We are focusing on three experimentally tractable HAB which are abundant in humans and which either require heme for respiration (Bacteroides thetaiotaomicron), are capable of but not dependent on heme-mediated respiration (Lactobacillus rhamnosus), or are obligately fermentative but still have limited uses for heme (Clostridium scindens). We will examine genes (via the generation of knock-outs) and gene products that are predicted to play important roles in heme metabolism in these species, but which belong to metabolic pathways that are typically incomplete. At the same time, we will employ discovery-based approaches to identify members of the heme-proteome, using chemically defined growth media, stable-isotope-labeled heme, and spectroscopic analyses with which we have a depth of expertise. Second, we will define how gut bacterial species work together and with the animal host to metabolize heme iron. As part of our experimental approach, we will use knock-out strains and isotopically labeled heme to examine heme metabolism by co-cultures, using subsets of the three HAB above and a common enteric heme heterotroph (Escherichia coli). Cocultures will be studied both in the flask and in mice with defined (gnotobiotic) microbiomes, in collaboration with Prof. Seth Walk (MSU). Understanding anaerobic heme metabolism by commensal bacteria serves the long-term biomedical goal of manipulating the microbiome to facilitate host metabolism of iron, thereby remediating diseases associated with iron deficiency (anemia) or excess (infection, colitis, inflammation, colon cancer).

项目概要 人们对消化道中普遍存在的细菌（其中大多数是厌氧菌）如何吸收和吸收知之甚少。 处理宿主的膳食铁，这种活动如何影响铁被吸收的效率。 宿主也不清楚缩小这一知识差距具有基础性和生物医学意义。 缺乏症和相关贫血是全世界最普遍的营养失调症，近乎 与此同时，红肉饮食中未代谢的血红素铁仍然存在。 结肠与从炎症到结肠癌等疾病的发展有关， 这项工作的长期目标是了解微生物活动如何发挥关键作用。 健康哺乳动物肠道中常见的共生细菌在低/无条件下代谢铁 拟议的工作重点关注该生态系统中普遍存在的氧气条件。 基础设施 – 经过 15 年在催化剂水平上研究有氧血红素/铁生物化学的积累， 细胞和生态系统——关于这个雄心勃勃的长期目标，我们将其分为两个重叠的部分。 首先，我们将研究常见的肠道微生物，其中大多数是厌氧、血红素营养缺陷型 细菌（HAB），代谢血红素，我们重点关注三种实验上可处理的HAB，它们是 人类中丰富且需要血红素进行呼吸的细菌（Bacteroides thetaiotaomicron），能够 但不依赖于血红素介导的呼吸（鼠李糖乳杆菌），或者是专性发酵的 但血红素（Clostridium scindens）的用途仍然有限。我们将检查基因（通过生成）。 敲除）和预计在这些物种的血红素代谢中发挥重要作用的基因产物， 但它们属于通常不完整的代谢途径，同时，我们将采用这些途径。 基于发现的方法，使用化学定义的生长来识别血红素蛋白质组的成员 我们拥有深厚的专业知识，包括介质、稳定同位素标记的血红素和光谱分析。 其次，我们将定义肠道细菌物种如何协同工作以及与动物宿主进行代谢 作为我们实验方法的一部分，我们将使用敲除菌株和同位素标记的血红素。 使用上述三种 HAB 的子集和常见的肠溶细胞通过共培养检查血红素代谢 将在烧瓶和具有明确定义的小鼠中研究血红素异养体（大肠杆菌）。 （限菌）微生物组，与 Seth Walk 教授（密歇根州立大学）合作了解厌氧血红素。 共生细菌的新陈代谢服务于操纵微生物组以实现长期生物医学目标 促进铁的宿主代谢，从而治疗与缺铁（贫血）相关的疾病或 过量（感染、结肠炎、炎症、结肠癌）。