IRON UPTAKE IN ACTINOBACILLUS ACTINOMYCETEMCOMITANS

伴放线放线杆菌中的铁吸收

• 批准号: 6516603
• 负责人: Luis A Actis
• 金额: $ 12.6万
• 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/6516603
• 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（改编自研究者摘要）：局限性幼年 牙周炎（LJP）是当细菌在牙周组织上积聚时发生的疾病。 口腔中的连接上皮。它被发现在 近十年来，伴放线放线杆菌是主要致病菌 LJP的代理人，最近，作为一种微生物负责 成人牙周炎牙周炎是最常见的慢性炎症 它是人类的主要疾病，也是牙齿脱落的主要原因。很明显 这种牙齿病原体在感染过程中活跃生长并持续存在， 这取决于这种微生物获得生长必需的 营养素如铁。脊椎动物宿主的铁抑制是一种有效的 因此，细菌必须表达 高效的运输系统来获取这种必需的营养物质， 在感染期间。有迹象表明，A。伴放线菌不 分泌铁载体化合物，它可以通过 周质结合蛋白依赖的运输系统。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 仍有待鉴定。因此，这一长期目标 应用是表征的机制，A. 放线菌共生菌用于获得铁和他们的参与 青少年和成人牙周炎的发病机制。在本提案中， 主要研究者通过几种方法来实现这些目标， 将经典和分子细菌遗传学中使用的方法与 分子生物学技术，旨在检查差异基因表达。 第一个具体的目标涉及详细的遗传和分子 表征两个潜在的铁周质运输系统，而 第二个具体的目标是集中分析这些系统的表达 在细菌培养基和组织培养中培养的细菌细胞中 含有单层人口腔上皮细胞的烧瓶。第三特定 aim建议确定这些潜在的铁运输系统在以下方面的作用： 铁的获得和A.放线菌共生体通过创造和 测试同基因突变体这些拟议的研究涉及一个重要的和 在很大程度上未探索的方面的发病机制所造成的A。 伴放线菌此外，这些研究将导致更好的 了解宿主与此之间相互作用的性质 病原体在定殖和侵入口腔组织期间。