MT VET COBRE PROJECT 2: HEME UPTAKE PATHWAYS IN GRAM-POSITIVE PATHOGENS

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者的研究机构。 主要的人类细菌病原体化脓性链球菌和金黄色葡萄球菌已经进化出有效地从宿主血红素蛋白获得血红素作为必需铁的优选来源的系统。因此，这些系统提供了几个潜在的治疗靶点，对这些系统的机制研究将提供临床相关的抗生素策略，以抑制由这些系统介导的血红素获取过程，用于治疗S。化脓链球菌和S.金黄色葡萄球菌感染 开发抗生素策略的转化研究需要首先理解和建立血红素获取过程的分子机制及其结构基础。 因此，雷博士的实验室设计了一种体外策略来阐明这些病原体中血红素获得的途径。 这些研究从物理上证明了血红素从一种蛋白质转移到另一种蛋白质，并使用动力学分析来确定血红素转移是否是定向的。 雷博士以前的研究结果表明，S。血红素从血红蛋白转移到Shr，然后转移到Shp，最后转移到HtsA的化脓性途径。雷博士现在发现，对于S。aureus系统：（1）血红蛋白直接将血红素转移到apo-IsdB;（2）holo-IsdB直接将血红素转移到apo-IsdA和apo-IsdC，但不转移到apo-IsdE;（3）apo-IsdE直接从holo-IsdC获得血红素，但不从holo-IsdB和holo-IsdA获得血红素;和（4）IsdB和IsdC分别增强血红素从血红蛋白到apo-IsdC和从holo-IsdB到apo-IsdE的转移。 这些结果建立了S.血红蛋白IsdB IsdA IsdC IsdE的金黄色葡萄球菌血红素转移途径。 这些结果极大地加深了我们对S.化脓链球菌和S.金黄色葡萄球菌，并可作为血红素收购在许多其他革兰氏阳性病原体的一般模型。 了解这些细菌如何利用血红素在人体内生存，可能会为如何阻止血红素运输提供线索，以开发新的治疗方法来对抗这些有害的病原体。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The major human bacterial pathogens Streptococcus pyogenes and Staphylococcus aureus have evolved the systems to efficiently acquire heme from host hemoproteins as a preferred source of essential iron. Thus, these systems provide several potential therapeutic targets, and the mechanistic study on these systems will provide clinically relevant antibiotic strategies to inhibit the heme acquisition process mediated by these systems for treating S. pyogenes and S. aureus infections. Translational studies to develop the antibiotic strategies need to first understand and establish the molecular mechanism of the heme acquisition process and its structural basis. Thus, Dr. Lei's lab has designed an in vitro strategy to elucidate the pathway of heme acquisition in these pathogens. These studies physically demonstrated heme transfer from one protein to another and used kinetic analysis to determine whether the heme transfer is directional. Dr. Lei's previous results indicated the S. pyogenes pathway of heme transfer from hemoglobin to Shr, then to Shp, and finally to HtsA. Dr. Lei has now discovered that for the S. aureus system: (1) hemoglobin directly transfers heme to apo-IsdB; (2) holo-IsdB directly transfers heme to apo-IsdA and apo-IsdC, but not to apo-IsdE; (3) apo-IsdE directly acquires heme from holo-IsdC, but not from holo-IsdB and holo-IsdA; and (4) IsdB and IsdC enhance heme transfer from hemoglobin to apo-IsdC and from holo-IsdB to apo-IsdE, respectively. These results establish a S. aureus heme transfer pathway of hemoglobin IsdB IsdA IsdC IsdE. These results greatly enhance our understanding of the mechanisms of heme acquisition in S. pyogenes and S. aureus and may serve as a general model for heme acquisition in many other Gram-positive pathogens. Understanding of how these bacteria utilize heme to survive in humans may provide clues on how to block the heme transport for developing new therapeutics to combat these harmful pathogens.