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

描述（由申请方提供）：拟杆菌属在人结肠中的定植。是建立和维持正常、健康的肠道植物群的基本要求，这种肠道关系的中断对健康和疾病有很大影响。为了使脆弱拟杆菌定殖于人类结肠，它们需要与微生物区系的其他微生物和宿主营养防御有效地竞争可用的营养。在拟杆菌所需的这些必需营养素中。是铁和血红素我们假设拟杆菌在清除未吸收的肠铁方面发挥重要作用，不仅是为了它们自身在大肠定植的生理需求，而且还为了储存铁，使其不易被结肠中的其他微生物获得。本研究的目的是确定大肠中未吸收的铁是否被B吸收。fragilis亚铁转运系统（FeoAB）和以无毒形式储存到铁储存蛋白铁蛋白（FtnA）中的铁蛋白作为模型系统来检验我们的假设B. fragilis使铁不能被肠道致病菌利用。因此，本研究的长期目标是更详细地研究B。脆弱菌是肠道微生物群落的一种寄生成分，在肠道定植过程中获得并储存铁。为了实现这些目标，将追求以下目标：目标1：我们将确定B的角色。fragilis FeO（AB）在铁吸收和肠道定植中的作用。1A.亚铁吸收量的测定。1B. Feo（A/B）在肠道定植中的作用及调节1B 1：用B定殖于无菌大鼠肠道。fragilis feo（A/B）突变体。1B 2：我们将通过实时RT-PCR评估体内feo（A/B）mRNA的表达。1C.铁的获得在竞争性肠道定植中的作用。知菌鼠与B的双重关联。fragilis突变体和E.杆菌目的2：我们将分析B的作用。fragilis FtnA在肠道铁储存和定植中的作用。2A.描述FtnA在肠道定植中的作用2B。我们将分析FtnA在B总铁含量中的作用。脆弱的2C.确定B的调节。fragilis ftnA mRNA。公共卫生相关性：本研究项目的新颖之处在于阐明了厌氧细菌B中铁的获取和储存机制。fragilis及其在细菌肠道定植和存活中的作用。我们的假设是，肠道细菌，如B。fragilis组通过清除结肠中未吸收的游离铁来保护肠粘膜免受病原菌的定植。这项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，以控制和操纵肠道微生物菌群。

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.