Branched Chain Amino Acid Metabolism During Anthrax

项目摘要 支链氨基酸(缬氨酸、亮氨酸和异亮氨酸)是生命所必需的。一些生物体， 像人类一样，从饮食中获得这些氨基酸，因此缺乏制造它们的能力。 其他的，如植物，拥有生产它们所需的全部生物合成机器，当 营养素很稀缺。有些致病细菌似乎两者兼而有之；它们产生了 能力，但也拥有转运体，调解他们从环境中吸收。 然而，目前还不清楚这两种武器中，收购和合成中哪一种最重要 在感染脊椎动物宿主的过程中。在这个项目中，我们使用了炭疽杆菌、 炭疽病的病原体，其在血液和组织中的大量复制使其成为理想的 为了研究营养吸收，确定支链氨基酸代谢对 这种病原体的多阶段感染过程。在杆菌需要的前提下工作 从血液蛋白质的分解中释放出支链氨基酸，以维持高水平的 在生长过程中，我们假设游离支链氨基酸在血清中的运输是必要的。 治疗炭疽病。在目标1中，我们使用在每条臂上都有缺陷的同源突变株(运输 与合成相比)，以确定它们对 肺炭疽病，最致命的一种。在目标2中，我们探索这两个手臂的确切作用 在杆菌感染周期的每个阶段，包括在受感染的巨噬细胞内生长 以及在血液和类似血液的环境中营养细菌的快速扩张。这项工作需要 了解支链氨基酸的生产和/或运输是否代表 新的抗微生物战略的可行切入点。

Project Summary Branched amino acids (valine, leucine, and isoleucine) are essential for life. Some organisms, like humans, acquire these amino acids from their diet and thus lack the ability to make them. Others, like plants, harbor the full biosynthetic machinery for their production and do so when nutrients are scarce. Some pathogenic bacteria seemingly do both; they have production capacity but also possess transporters that mediate their uptake from the environment. However, it is unclear which of these two arms, acquisition versus synthesis, is most important during infection of their vertebrate hosts. In this project, we employ the use of B. anthracis, the causative agent of anthrax disease whose prolific replication in blood and tissues makes it ideal for studying nutrient uptake, to determine the importance of branched amino acid metabolism to the multi-stage infectious process of this pathogen. Working under the premise that bacilli needs to liberate branched amino acids from the breakdown of blood proteins to sustain high levels of growth, we hypothesize that the transport of freed branched amino acids in serum is necessary for anthrax disease. In Aim 1, we use isogenic mutant strains deficient in each arm (transport versus synthesis) of branched amino acid metabolism to determine their overall contribution to pulmonary anthrax, the most lethal type. In Aim 2, we explore the exact role of these two arms to each stage in the infectious cycle of bacilli, including outgrowth inside infected macrophages and rapid expansion of vegetative bacilli in blood and blood-like environments. This work takes the first step towards knowing if branched amino acid production and/or transport represents a viable entry point for new antimicrobial strategies.