IRON UPTAKE IN ACTINOBACILLUS ACTINOMYCETEMCOMITANS

伴放线放线杆菌中的铁吸收

• 批准号: 6083362
• 负责人: Luis A Actis
• 金额: $ 14.85万
• 依托单位: MIAMI UNIVERSITY OXFORD
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6083362
• 关键词: Actinobacillus actinomycetemcomitans; SDS polyacrylamide gel electrophoresis; bacteria infection mechanism; bacterial genetics; bacterial proteins; clone cells; epithelium; gene expression; genetic library; genetic mapping; genetic promoter element; iron metabolism; membrane transport proteins; mutant; northern blottings; nucleic acid sequence; operon; oral bacteria; pathologic process; periodontitis; polymerase chain reaction; siderophores; site directed mutagenesis; southern blotting; virulence; western blottings

DESCRIPTION (adapted from the Investigator's abstract): Localized juvenile periodontitis (LJP) is the disease that occurs when bacteria accumulate on the junctional epithelium in the oral cavity. It was found in the middle of the last decade that Actinobacillus actinomycetemcomitans is the major causative agent of LJP and, more recently, as one of the microorganisms responsible for adult periodontitis. Periodontitis is the most prevalent chronic inflammatory diseases in humans, and it is major cause of tooth loss. It is evident that this dental pathogen grows actively and persists during the infectious process, which depends upon the ability of this microorganism to obtain growth-essential nutrients such as iron. Iron withholding by vertebrate hosts is an efficient mechanism against bacterial infections, and, thus bacteria must express efficient transport systems to acquire this essential nutrient to multiply during infection. There are indications that A. actinomycetemcomitans does not secrete siderophore compounds and it may acquire iron through periplasmic-binding protein-dependent transport systems. However, the genes and bacterial products involved in these processes and their role in virulence remain to be characterized. Therefore, the long-term objective of this application is the characterization of the mechanisms that A. actinomycetemcomitans uses to acquire iron and their participation in the pathogenesis of juvenile and adult periodontitis. In this proposal, the Principal Investigator addresses these goals through several approaches, combining methods used in classical and molecular bacterial genetics with molecular biology techniques designed to examine differential gene expression. The first specific aim involves a detailed genetic and molecular characterization of two potential iron periplasmic-transport systems, while the second specific aim focuses on the analysis of the expression of these systems in bacterial cells cultured in bacteriological media and in tissue culture flasks containing monolayers of human oral epithelial cells. The third specific aim proposes to determine the role of these potential iron transport systems in iron acquisition and the virulence of A. actinomycetemcomitans by creating and testing isogenic mutants. These proposed studies address an important and largely unexplored aspect of the pathogenesis caused by A. actinomycetemcomitans. Furthermore, these studies will lead to a better understanding of the nature of the interactions between the host and this pathogen during colonization and invasion of oral tissues.

描述（改编自研究者的摘要）：本地化青少年 牙周炎（LJP）是细菌积聚在牙周组织上而发生的疾病。 口腔内的交界上皮。它被发现在中间 近十年来，伴放线放线杆菌是主要致病菌 LJP 的代理人，最近，作为负责的微生物之一 成人牙周炎。牙周炎是最常见的慢性炎症 人类疾病，它是牙齿脱落的主要原因。显然， 这种牙科病原体在感染过程中活跃生长并持续存在， 这取决于该微生物获得生长必需的能力 铁等营养物质。脊椎动物宿主的铁保留是一种有效的 对抗细菌感染的机制，因此细菌必须表达 高效的运输系统获取这种繁殖所必需的营养 感染期间。有迹象表明 A. actinomycetemcomitans 不 分泌铁载体化合物，它可以通过以下方式获取铁： 周质结合蛋白依赖性运输系统。然而，基因和 参与这些过程的细菌产物及其在毒力中的作用 仍有待表征。因此，本次活动的长远目标 应用是 A. 机制的表征。 放线菌用于获取铁及其参与 青少年和成人牙周炎的发病机制。在该提案中， 首席研究员通过多种方法实现这些目标， 将经典和分子细菌遗传学中使用的方法与 旨在检查差异基因表达的分子生物学技术。 第一个具体目标涉及详细的遗传和分子研究 两种潜在的铁周质运输系统的表征，而 第二个具体目标侧重于分析这些系统的表达 在细菌培养基和组织培养物中培养的细菌细胞中 含有单层人类口腔上皮细胞的烧瓶。第三具体 目标建议确定这些潜在的铁运输系统在 铁的获取和 A. actinomycetemcomitans 的毒力通过创建和 测试同基因突变体。这些拟议的研究解决了一个重要且 A. 引起的发病机制在很大程度上尚未被探索。 伴放线菌。此外，这些研究将带来更好的结果 了解宿主与其之间相互作用的本质 病原体在口腔组织定植和侵袭期间。