METABOLIC REGULATION OF STAPHYLOCOCCAL PATHOGENESIS

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。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。所列机构为中心机构，不一定为研究者机构。金黄色葡萄球菌（Staphylococcus aureus）是一种革兰氏阳性病原体，在人类和动物中引起多种疾病。它是医院获得性感染的主要原因，每年花费美国超过45亿美元。大多数S.生长的指数期的特征在于细胞相关粘附因子的产生（例如，纤连蛋白结合蛋白）而生长的后指数期以分泌的毒力因子的产生为特征（例如，α-毒素）。伴随着进入生长的指数后期，三羧酸（TCA）循环活性增加。柠檬酸酶是将柠檬酸盐转化为异柠檬酸盐的TCA循环酶。真核生物具有线粒体和细胞质顺乌头酸酶活性。细胞质顺乌头酸酶活性是由铁响应蛋白-1（IRP-1）引起的，IRP-1是一种转录后调节铁调节蛋白合成的mRNA结合蛋白。因此，胞质乌头酸酶是一种双功能蛋白质。最近，已经证明来自枯草芽孢杆菌和大肠杆菌的顺乌头酸酶以铁依赖的方式与mRNA中的序列特异性元件结合。这些观察建立了细菌乌头酸酶，像真核细胞溶质乌头酸酶/IRP-1，作为一种双功能蛋白。灭活的唯一S。金黄色葡萄球菌顺乌头酸酶基因（acnA/citB），显著降低毒力因子的合成，改变宿主-病原体相互作用，并增强稳定期存活。顺乌头酸酶失活的影响可能是TCA循环中代谢阻断、调节功能丧失或两者结合的结果。我们建议确定哪些影响乌头酸酶失活是由于代谢缺陷，哪些是由于失去了监管功能。此外，我们将确定乌头酸酶是否会与被鉴定为可能受乌头酸酶调节的基因的同源mRNA结合。[Lay细菌是“吃”和分裂的单细胞生物;因此，细菌所做的一切都与进食和分裂有关，包括引起人类疾病。对细菌如何调节致病机制以应对营养限制的基本理解对于开发旨在杀死细菌的新治疗方法至关重要。该提案中包含的工作是设计对抗细菌感染的新策略的第一步。

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. Staphylococcus aureus is a Gram-positive pathogen that causes a wide variety of diseases in humans and animals. It is a leading cause of hospital acquired infections, costing the United States more than 4.5 billion dollars annually. The expression of most S. aureus virulence factors is determined by the growth phase.The exponential phase of growth is characterized by the production of cell associated adhesion factors (e.g., fibronectin binding protein) while the post-exponential phase of growth is distinguished by the production of secreted virulence factors (e.g., alpha-toxin). Concomitant with the entry into the post-exponential phase of growth is an increase in tricarboxylic acid (TCA) cycle activity. Aconitase is a TCA cycle enzyme that converts citrate to isocitrate. Eukaryotic organisms have mitochondrial and cytoplasmic aconitase activity. The cytoplasmic aconitase activity is caused by the iron-responsive protein-1 (IRP-1), an mRNA-binding protein that posttranscriptionally regulates the synthesis of iron-regulated proteins. Thus, cytosolic aconitase is a bifunctional protein. Recently, it has been demonstrated that aconitase from Bacillus subtilis and Escherichia coli bind to sequence specific-elements in mRNAs in an iron-dependent fashion. These observations established bacterial aconitase, like eukaryotic cytosolic aconitase/IRP-1, as a bifunctional protein. Inactivation of the sole S. aureus aconitase gene (acnA/citB), significantly decreases virulence factor synthesis, alters host-pathogen interaction, and enhances stationary phase survival. The affects of aconitase inactivation can be the result of a metabolic block in the TCA cycle, the loss of regulatory function, or a combination of the two. We propose to determine which affects of aconitase inactivation are due to a metabolic defect and which are due to the loss of regulatory function. Additionally, we will determine if aconitase will bind to the cognate mRNAs of genes identified as potentially regulated by aconitase. [Lay Summary] Bacteria are single celled organisms that "eat" and divide; therefore, everything bacteria do is linked to eating and dividing, including causing disease in humans. A fundamental understanding of how bacteria regulate pathogenesis in response to nutrient limitation is critical to developing new treatments designed to kill bacteria. The work contained within this proposal is a first step in designing new strategies to combat bacterial infections.