The role of iron/heme acquisition mechanisms in Bacteroides fragilis.

描述（由申请人提供）：拟杆菌属（Bacteroides）在人类结肠中的定植是建立和维持正常、健康肠道菌群的基本要求，这种共生关系的破坏对健康和疾病有很大影响。为了使脆弱拟杆菌在人类结肠中定植，它们需要与其他微生物和宿主的营养防御系统有效地竞争可用的营养物质。拟杆菌所需的这些必需营养素包括铁和血红素。我们假设拟杆菌在清除未被吸收的肠铁中发挥重要作用，这不仅是为了它们在大肠定植的生理需要，也是为了储存铁，使结肠中的其他微生物难以接近铁。我们的研究目标是确定大肠中未被吸收的铁是否被易碎芽孢杆菌亚铁转运系统（FeoAB）吸收，并以无毒的形式储存到铁储存蛋白铁蛋白（FtnA）中，作为模型系统来验证我们的假设，即易碎芽孢杆菌使铁无法被肠道致病菌获取。因此，本研究的长期目标是更详细地研究肠道微生物群落的共生成分脆弱芽孢杆菌在肠道定植过程中获取和储存铁的方式。为了实现这些目标，将追求以下目标：[段落]目标1：我们将确定易碎芽孢杆菌Feo（AB）在铁摄取和肠道定植中的作用。1一个。亚铁吸收的测定。1 b。feo（A/B）在肠道定植中的作用及调控1B1: A/B突变体在非生物大鼠肠道的定植。1B2：我们将通过Real-Time RT-PCR评估feo(A/B) mRNA在体内的表达。1 c。铁获取在竞争性肠道定植中的作用。易碎芽孢杆菌突变体和大肠杆菌的双重关联。【段落】目的2：我们将分析脆弱芽孢杆菌FtnA在肠道铁储存和定植中的作用。2 a。描述FtnA在肠道定植2B中的作用。我们将分析FtnA在脆弱芽孢杆菌总铁含量中的作用。2 c。确定脆弱芽孢杆菌fna mRNA在体内的调控。公共卫生相关性：本研究项目的新方面在于阐明了厌氧菌脆弱芽孢杆菌的铁获取和储存机制及其在细菌肠道定植和生存中的作用。我们的假设是肠道共生细菌，如易碎芽孢杆菌群，通过清除结肠中未被吸收的游离铁来保护肠黏膜免受致病菌的定植。本研究旨在提供新的信息，可能导致新的益生元和益生菌治疗策略，以控制和操纵肠道菌群。

DESCRIPTION (provided by applicant): The colonization of the human colon by Bacteroides spp. is a fundamental requirement for the establishment and maintenance of a normal, healthy intestinal flora and a disruption in this commensal relationship has a great impact on health and disease. In order for Bacteroides fragilis to colonize the human colon, they need to compete efficiently for the available nutrients with other microorganisms of the microflora and host nutritional defenses. Among these essential nutrients required by Bacteroides spp. are iron and heme. We postulate that Bacteroides play an important role in scavenging non-absorbed intestinal iron not only for their own physiological requirements for colonization of the large intestine but also to store iron, making it less accessible to other microorganisms in the colon. It is our goal in this research proposal to determine if non-absorbed iron in the large intestine is taken up by B. fragilis ferrous iron transport system (FeoAB) and stored into the iron storage protein ferritin (FtnA) in a non-toxic-form as a model system to test our hypothesis that B. fragilis makes iron unavailable to intestinal pathogenic bacteria. The long-term objective of this study is therefore to investigate in more detail the way B. fragilis, a commensal component of the intestinal microflora acquire and store iron during intestinal colonization. To accomplish these objectives, the following aims will be pursued: [PARAGRAPH] Aim 1: We will determine the role of B. fragilis Feo(AB) in iron uptake and intestinal colonization. 1A. Determination of ferrous iron uptake. 1B. Role and regulation of feo(A/B) in the colonization of the intestinal tract.. 1B1: Colonization of gnotobiotic rat intestinal tract with B. fragilis feo(A/B) mutant. 1B2: We will assess the expression of feo(A/B) mRNA in vivo by Real-Time RT-PCR. 1C. Role of iron acquisition in competitive gut colonization. Dual-association of gnotobiotic rats with B. fragilis mutants and E. coli. [PARAGRAPH] Aim 2: We will analyze the role of B. fragilis FtnA in iron-storage and colonization of intestinal tract. 2A. Delineate the role of FtnA in intestinal colonization 2B. We will analyze the role of FtnA in total iron content of B. fragilis. 2C. Determine the regulation of B. fragilis ftnA mRNA in vivo. PUBLIC HEALTH RELEVANCE: The novel aspect of this research project resides in the elucidation of the iron acquisition and storage mechanisms in the anaerobe B. fragilis and their role in bacterial intestinal colonization and survival. Our hypothesis is that intestinal commensal bacteria, such as B. fragilis group protect the intestinal mucosa against colonization of pathogenic bacteria by scavenging non-absorbed free iron in the colon. This study is aimed to provide new information that may lead to new prebiotics and probiotics therapeutic strategies to control and manipulate the intestinal microflora population.