Acinetobactin and C-Glucosylated Enterobactin Siderophores

第一个焦点是开启铁载体生物合成基因的肠杆菌菌株 肠杆菌素在铁是有限的微环境中，包括脊椎动物宿主。肠杆菌素结合铁 铁是贪婪的，并受到生产细菌的特异性摄取。一些致病性革兰氏阴性 进一步阐述肠杆菌素支架以制备C-葡糖基化形式，也称为来自 它们是在清除铁的伤寒沙门氏菌菌株中发现的。产生Salmochelin的细菌使Ent 在Iro基因簇IroBCDEN的指导下构建支架。我们将研究C- 通过IroB的葡糖基化，并确定在何种程度上的二羟基苯环的葡糖基化， 内皮细胞支架干扰哺乳动物宿主蛋白铁载体的螯合作用。 未能螯合修饰的肠杆菌素应该与细菌的致病性增加相关。 第二个焦点是革兰氏阴性菌产生铁载体抗氧化蛋白 呼吸道病原体鲍曼不动杆菌铁载体的产生与毒力的增加相关。 acinegalactin具有所有三个已知的铁螯合基团，儿茶酚，噻唑啉和异羟肟酸， 通过非核糖体肽合成酶装配线将其转化为骨骼肌。六个基因BasABCDEF编码 铁载体合成酶装配线。我们计划过量生产每种蛋白质，并评估以下内容 装配线操作的不寻常特征预测：两个独立的腺苷酸化和 硫醇化结构域，通过串联缩合结构域的环化脱氢，链形成过程中的异羟肟酸盐形成 铁载体成熟终止。Salrnochelin和Acineactin的表征 生物合成酶将是随后评估酶抑制剂的基础， 阻止铁载体的产生。

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.