Siderophore Synthetases in Three Bacterial Pathogens

超出所提供的空间。铁螯合物是由缺乏铁的微环境中的细菌合成、输出和回收的，因此螯合物（也称为铁载体）作为致病菌感染脊椎动物的毒力因子，如鼠疫中的鼠疫耶尔森菌、霍乱流行中的霍乱弧菌和CF患者肺部感染中的铜绿假单胞菌。各自的铁载体，Ybt， vibriobactin和Pch，是由非核糖体肽合成酶（NRPS）在缺铁激活下产生的。通过混合NRPS/PKS装配线将yersinabactin组装为非核糖素肽和聚酮（PK）的混合物。该装配线的NRPS/PKS和PKS/NRPS开关点将用纯化的Ybt合成酶的多模亚基进行检测。Ybt还具有串联双噻唑啉环体系，并且在17结构域的Ybt装配线中嵌入了来自环化（Cy）和c -甲基化（MT）结构域的异常c -甲基化。Cy和MT催化结构域的机制将被检查。Pch装配线涉及四种蛋白质和一系列酰基s -酶中间体，将分析特定链延伸步骤的时间和位点，包括杂环噻唑啉环还原为噻唑烷，然后分别由PchG亚基和PchF亚基的N-MT结构域进行n -甲基化。由于Ybt和PCh铁载体蛋白的相似性，PCh和Ybt装配线内部和之间的结构域和模块的蛋白质识别将被检查，以开始建立这种NRP分子的组合生物合成规则。第三种致病的铁载体系统，Vib合成酶在Pch和Ybt中组装支链铁载体并产生恶唑啉环（来自苏氨酸）而不是噻唑啉环（来自半胱氨酸）。在Vib组装线上有两个Cy结构域和三个缩合(C)结构域，所有这五个链延伸催化结构域的功能将通过生化分析和诱变来研究，以破译这些nrps组装的分子逻辑。了解机制，例如杂环化Cy结构域的机制，可以设计抑制剂来阻止这些多模块酶产生铁载体。网站性能 ======================================== 节结束 ===========================================

EXCEED THE SPACE PROVIDED. Iron chelators are synthesized, exported and retrieved by bacteria in iron-deficient microenvironments aid thus chelatars, also known as siderophores, serve as virulence factors for infections in vertebrates by pathogens such as Yersinia pestis in plague, Vibrio cholerae in cholera epidemics, and Pseudomonas aeruginosa in lung infection in CF patients. The respective siderophores, yersiniabactin (Ybt), vibriobactin(Vib), and pyochelin(Pch),are produced by non-ribosomal peptide synthetases(NRPS),activated by iron depletion. Yersiniabactin is assembled as a hybrid of a nonribosornal peptide and a polyketide (PK) by a mixed NRPS/PKS assembly line. The NRPS/PKS and PKS/NRPS switchpointsof this assembly line will be examined with purified multimodular subunits of Ybt synthetase. Ybt also has a tandem bithiazoline ring system and unusual C-methylations from Cyclization(Cy) and C-methylation(MT) domains embedded in the 17 domain Ybt assembly line. The mechanisms of the Cy and MT catalytic domains will be examined. The Pch assembly line involves four proteins and a cascade of acyl-S-enzyme intermediates that will be analyzed for timing and locus of specific chain elongation steps, including heterocyclic thiazoline ring reduction to thiazolidine and then subsequent N-methylationby the PchG subunit and the N-MT domain of the PchF subunit respectively. Because of the similarity of the Ybt and PCh siderophores protein-protein recognitionof domains and modules within and between the Pch and Ybt assembly lines will be examined to begin to establish rules for combinatorial biosynthesis of such NRP molecules. The third pathogenic siderophore system, the Vib synthetase assembles a branched siderophore and produces an oxazoline ring (from threonine) rather than the thiazoline riongs (from cysteine) in Pch and Ybt. There are two Cy domains and three Condensation (C) domains in the Vib assembly line and the function of all five of thesechain-elongation catalytic domains will be examined by biochemical analysis and mutagenesis to decipher the molecular logic of these NR.PS assemblies. Understanding of mechanism, e.g. of the heterocyclizing Cy domains may allow inhibitor design to block siderophore production by these multimodular enzymes. PERFORMANCE SITE ========================================Section End===========================================