Acinetobactin and C-Glucosylated Enterobactin Siderophores

第一个焦点是启动铁载体生物合成基因的肠杆菌菌株。 在铁限制的微环境中，包括脊椎动物宿主中的肠动蛋白。肠杆菌素与铁结合 铁的贪婪，并受到产生细菌的特定摄取。一些病原性革兰氏阴性 进一步细化肠结肠素支架，以制备C-葡萄糖化形式，也称为Salmochelin，来自 他们在清除铁的伤寒沙门氏菌菌株中发现。Salmochelin产生菌为Ent量身定做 在Iro基因簇IroBCDEN的指导下构建支架。我们将研究C-的酶作用机理。 IroB的糖基化反应，并测定二羟基苯环的糖基化程度 ENT支架干扰哺乳动物宿主蛋白铁胆碱对铁载体的隔离。 未能隔离修饰的肠杆菌素应该与细菌的致病性增加有关。 第二个焦点是由革兰氏阴性菌产生铁载体acinobactin。 呼吸道病原菌鲍曼不动杆菌。铁载体的产生与毒力的增加相关。 Acinetobactin有所有三个已知的铁络合基，儿茶酚，噻唑啉和异羟甲酸酯，内置于其 一条非核糖体多肽合成酶装配线。六个基因为ABCDEF编码 铁载体合成酶生产线。我们计划大量生产每种蛋白质，并评估以下各项 装配线操作的不同寻常的特征预测：两个独立的腺化作用和 硫代化结构域，串联缩合结构域的环脱氢反应，链中异羟甲酸酯的形成 在铁载体成熟时终止。Salrnochelin和Acinetobactin的性质研究 生物合成酶将是随后评估酶抑制剂的基础，这些酶抑制剂可能 阻止铁载体的生产。

The first focus is on enterobacterial strains that turn on biosynthetic genes for the siderophore enterobactin in microenvironments where iron is limiting, including vertebrate hosts. Enterobactin binds ferric iron avidly and is subjected to specific uptake by the producing bacteria. Some pathogenic gram negatives further elaborate the enterobactin scaffold to make C-glucosylated forms, also known as salmochelins from their discovery in iron-scavenging salmonella typhi strains. Salmochelin-producing bacteria tailor the Ent scaffold under direction of the Iro gene cluster IroBCDEN. We will study the enzymatic mechanism for C- glucosylation by IroB and determine to what extent the glucosylation of the dihydroxybenzene rings of the Ent scaffold interfere with sequestration of the siderophore by the mammalian host protein siderocalin. Failure to sequester the modified enterobactins should correlate with increased pathogenicity of the bacteria. The second focus is on the productuiion of the siderophore acinteobactin by the gram negative respiratory pathogen Acinetobacter baumanii. Siderophore production correlates with increased virulence. Acinetobactin has all three known-iron chelating groups, catechol, thiazoline, and hydroxamate, built into its skeleon by a nonribosomal peptide synthetase assembly line. The six genes BasABCDEF encode the siderophore synthetase assembly line. We plan to overproduce each protein and evaluate the following unusual featiures predicted for assembly line ooperations: action of two free standing adenylation and thiiolation domains, cyclodehdration by tandem condensation domains, hydroxamate formation during chain termination in siderophore maturation. Characterization of the salrnochelin and acinetobactin biosynthesizing enzymes will be the foundation for subsequent evaluation of enzyme inhibitors that might block siderophore production.