Genetics of Iron Acquisition by Legionella pneumophila

嗜肺军团菌获取铁的遗传学

• 批准号: 7151179
• 负责人: NICHOLAS P CIANCIOTTO
• 金额: $ 31.45万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-04-01 至 2009-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7151179
• 关键词: Aconitate Hydratase; Aconitic Acid; Address; Aerosols; Alveolar Macrophages; Amoeba genus; Antibiotics; Assimilations; Behavior; Biological Assay; Cells; Cytochrome c Group; Cytochromes; Data; Defect; Disease; Exhibits; Genes; Genetic; Grant; Growth; Habitats; Heme; Individual; Infection; Iron; Laboratories; Leadership; Legionella; Legionella pneumophila; Legionnaires' Disease; Lung; Mammalian Cell; Methyltransferase; Microbial Biofilms; Modeling; Mus; Mutation; Operon; Parasites; Pathogenesis; Phenotype; Physiology; Pigments; Play; Production; Protozoa; Regulation; Research; Respiration; Respiratory System; Role; Siderophores; Structure; System; Virulence; Water; Work; cold temperature; cytochrome c; expectation; extracellular; ferrochelatase; in vivo; inhibitor/antagonist; insight; macrophage; man; member; mutant; novel; trans-aconitate methyltransferase; uptake

DESCRIPTION (provided by applicant): Legionella pneumophila (Lp) is the agent of Legionnaires' disease. It is ubiquitous in natural and man-made water systems, infecting individuals after aerosol inoculation. In aquatic habitats, Lp survives in biofilms and as an intracellular parasite of protozoa, whereas in the lung, it flourishes as a parasite of macrophages. Iron is vital to Lp growth in extra- and intracellular niches and its ability to cause disease. During this grant period, we discovered that Lp expresses a siderophore (legiobactin) that is novel in structure and regulation, the first such data in nearly 20 years of Lp research. We then demonstrated the ability of legiobactin-containing supernatants to stimulate the growth of iron-starved legionellae, purified the siderophore, and identified two genes (lbtAB) required for its expression. In other work, we characterized an Lp mutant that is highly defective for growth in low iron, macrophages, and the lung and showed that the inactivated gene (iraA) encodes a methyltransferase, whose predicted target is trans-aconitate, an inhibitor of aconitase. During this grant period, we also found that the cytochrome c maturation (ccm) operon plays a key role in Lp growth in low iron, in host cells, and in the mammalian lung. The role for iraA and ccrn in low iron and infection is without precedent. Finally, we identified an Lp ferrous transport system that is important for infection, a ferrioxidase that promotes iron assimilation, and an iron-dependent pigment that facilitates antibiotic formation. In this proposal, we will i) determine the role of legiobactin in vivo and in environmental situations, including biofilms, ii) seek the additional genes that encode the Lp siderophore, iii) determine if iraA indeed encodes a trans-aconitate methyltransferase that promotes infection by modulating aconitase, and iv) determine how the ccm locus promotes iron uptake and whether it does so by facilitating cytochrome maturation, heme export, or a novel undefined function. Taken together, these studies will increase our specific understanding of Lp physiology and pathogenesis as well as provide new general insight into siderophores and the mechanisms of iron acquisition, methyltransferases and aconitases as iron-responsive regulators, cytochromes and intracellular respiration, macrophage infection, virulence in the respiratory tract, and bacterial environmental survival in water, biofilms and low-temperature amoebae.

描述（由申请人提供）：肺炎军团（LP）是军团疾病的推动者。它在天然和人造的水系统中无处不在，在接种气溶胶后感染了个体。在水生栖息地中，LP在生物膜中生存，作为原生动物的细胞内寄生虫，而在肺部，它作为巨噬细胞的寄生虫繁荣发展。铁对于细胞内和细胞内壁ni的LP生长至关重要及其引起疾病的能力。在这一赠款期间，我们发现LP表达了一个新颖的结构和调节的铁载体（Legiobactin），这是LP研究近20年中的第一个此类数据。然后，我们证明了含legiobactin的上清液刺激铁star型军团eLLAE的生长，纯化铁载体的能力，并确定了其表达所需的两个基因（LBTAB）。在其他工作中，我们表征了一个LP突变体，该突变体对于低铁，巨噬细胞和肺部的生长高度有缺陷，并表明灭活基因（IRAA）编码了甲基转移酶，其预测的靶标是跨核酸酯，是刺激酶的抑制剂。在此赠款期间，我们还发现细胞色素c成熟（CCM）操纵子在低铁，宿主细胞和哺乳动物肺中LP生长中起关键作用。 IRAA和CCRN在低铁和感染中的作用是没有先例的。最后，我们确定了一种对感染很重要的LP亚铁运输系统，一种促进铁同化的铁氧化酶以及促进抗生素形成的铁依赖性色素。在这项提议中，我们将i）确定legiobactin在体内和环境环境中的作用，包括生物膜，ii）寻求编码LP Siderophore的其他基因，iii）确定IRAA是否编码了跨核酸的甲基转移酶是否确实编码了通过调节辅助和IV促进的跨性别的甲基转移酶，并确定是否促进aconitase和iv aConitase和iv）是否促进了IV，以及是否促进aconitase和IV）。促进细胞色素成熟，血红素导出或新型不确定功能。 Taken together, these studies will increase our specific understanding of Lp physiology and pathogenesis as well as provide new general insight into siderophores and the mechanisms of iron acquisition, methyltransferases and aconitases as iron-responsive regulators, cytochromes and intracellular respiration, macrophage infection, virulence in the respiratory tract, and bacterial environmental survival in water, biofilms and低温变形虫。