Iron Acquisition in Anthrax

描述（由申请方提供）：细菌病原体必须获得铁才能在哺乳动物宿主中复制和存活。铁卟啉血红素，结合到循环血红蛋白，含有高达80%的身体铁。这一事实导致了一个有实验证据支持的假设，即血红素在感染过程中是铁的来源。然而，在炭疽病菌B。在炭疽杆菌中，铁调节表面决定簇（Isd）基因（编码结合血红素的表面蛋白）的缺失并没有减少B。炭疽菌在动物感染模型中的毒力。这些结果表明，其他因素有助于这种致命病原体的铁吸收。Isd系统的一个标志是存在一个保守的蛋白模块，称为近铁转运蛋白（NEAT）结构域，介导血红素转移到革兰氏阳性病原菌。B基因组的计算机分析。炭疽杆菌指示命名为BAS 0520的非Isd基因被注释为编码单个NEAT结构域蛋白。本提案的目的是确定BAS 0520是否代表炭疽感染期间介导血红素摄取的“缺失环节”。具体来说，我们假设BAS 0520是一种表面蛋白，从宿主血红蛋白中提取血红素，从而促进血红素转运到细菌细胞中，并增强哺乳动物宿主中的铁依赖性复制。这个假设将被测试有两个目标：1。确定BAS 0520的机械功能。生物化学方法将定义BAS 0520的NEAT结构域的分子和结构因子。2.确定BAS 0520在铁获得和炭疽病中的作用。使用完全毒力菌株的生长研究和动物感染模型将用于确定铁吸收的机制对炭疽病是重要的。

DESCRIPTION (provided by applicant): Bacterial pathogens must acquire iron to replicate and survive in mammalian hosts. The iron-porphyrin heme, bound to circulating hemoglobin, contains up to 80% of bodily iron. This fact has led to the hypothesis, which is backed by experimental evidence, that heme serves as a source of iron during infection. However, in the anthrax-causing bacteria B. anthracis, deletion of iron-regulated surface determinant (Isd) genes, which code for surface proteins that bind heme, did not reduce B. anthracis virulence in animal models of infection. These results suggest other factors contribute to iron uptake in this deadly pathogen. A hallmark of Isd systems is the presence of a conserved protein module termed the near-iron transporter (NEAT) domain, which mediates the transfer of heme into Gram-positive pathogenic bacteria. In silico analysis of the genome of B. anthracis indicates a non-Isd gene, designated BAS0520, is annotated to encode for a single NEAT-domain protein. The objective of this proposal is to determine if BAS0520 represents the "missing link" mediating heme uptake during anthrax infection. Specifically, we hypothesize BAS0520 is a surface protein that extracts heme from host hemoglobin, thereby promoting heme transport into the bacterial cell and enhancing iron-dependent replication in mammalian hosts. This hypothesis will be tested with two aims: 1. Determine the mechanistic function of BAS0520. Biochemical approaches will define the molecular and structural factors of the NEAT domain of BAS0520. 2. Determine the role of BAS0520 in iron acquisition and anthrax disease. Growth studies and animal infection models using fully virulent strains will be used to define which mechanisms of iron uptake are important for anthrax disease.