Mechanistic Studies of Alkyl Hydroperoxide Reductase and Related Redox Systems

过氧化氢是人类免疫系统用来杀死传染性生物的一种毒素，以及 越来越多的证据表明，它也是真核信号中常见的第二信使。在……里面 人类，肿瘤坏死因子、表皮生长因子和胰岛素是被认为是激素的三个例子 通过过氧化氢发出信号。过氧化氢酶和谷胱甘肽过氧化物酶一直被认为是主要的 然而，在过去的几年里，在细胞中降解过氧化物酶的一个独特的、高度丰富的家族 过氧化还原酶，过氧化还蛋白(Prxs)，已经从相对默默无闻变成了主要的 氧化还原生物学研究的焦点。多年来，真核生物Prxs的过氧化物酶活性一直被忽视， 因为那些在真核生物中高表达的Prx很容易被过氧化氢灭活。我们有 在十多年来对致病性Prx的特征进行表征的过程中，发展了Prx酶学方面的专业知识 细菌(如鼠伤寒沙门氏菌AhpC)。这些Prx是抗生素开发的目标，因为 它们在保护细菌免受人类免疫系统侵害方面所起的作用。在2003年，我们的结构和 通过对鼠伤寒沙门氏菌AhpC的功能研究，我们发现了其对沙门氏菌敏感的结构基础。 在所有真核生物中高度表达的PrX的一个子集所保守的过氧化物质。我们进一步 提出了“闸门假说”，即这种对失活的敏感性如何在 其中过氧化氢被用作信号分子的生物体，因此抗氧化剂特性 可以在适当的条件下关闭PRX，以允许过氧化氢的受控爆发 级别。鉴于Prxs在病原体防御和人类细胞中对抗氧化的重要性 对于压力和细胞调节，我们建议在这里扩大我们的研究计划，通过继续我们的 阐明催化的基本结构和生物化学方面的成熟工作 各种已知的Prx(特定目标1、2和4)，并通过开发一种新的系统生物学方法来 了解Prxs和其他过氧化物酶在真核细胞过氧化平衡中的相对作用 细胞(特定目标3)。 氧化损伤被认为在衰老、癌症的发展和许多 退行性疾病。此外，控制增殖的细胞信号过程中的损伤， 分化和细胞凋亡与多种疾病状态有关。加深对Prxs的认识 因此，它们在细胞信号和抗氧化保护中所起的作用将具有重要意义。 用于预防人类疾病。此外，Prxs在保护人类病原体免受 免疫系统的杀伤作用使Prxs成为开发新的治疗药物的靶点 抗击传染病。

Hydrogen peroxide is a toxin used by the human immune system to kill infectious organisms, and increasing evidence is accumulating that it is also a common second messenger in eukaryotic signaling. In humans, tumor necrosis factor, epidermal growth factor and insulin are three examples of hormones thought to signal via hydrogen peroxide. Catalase and glutathione peroxidase have long been viewed as the major nzymes degrading peroxide in cells, however, over the past few years, a distinct, highly abundant family of peroxide-reducing enzymes, peroxiredoxins (Prxs), have moved from relative obscurity to become a major Focus of redox biology research. The peroxidase activity of eukaryotic Prxs was overlooked for many years, because those Prxs that are highly expressed in eukaryotes are easily inactivated by peroxide. We have developed expertise in Prx enzymology over more than a decade of characterizing of Prxs from pathogenic bacteria (e.g. Salmonella typhimurium AhpC). These Prxs are targets for antibiotic development because of the role they play in protecting the bacteria from the human immune system. In 2003, our structural and functional studies on S. typhimurium AhpC led us to discover the structural basis for the sensitivity toward peroxides that is conserved for a subset of Prxs that are highly expressed across all eukarya. We further proposed the "floodgate hypothesis" for how this sensitivity to inactivation would actually be beneficial in organisms where hydrogen peroxide is being used as a signaling molecule, so that the antioxidant properties of the Prxs could be switched off under appropriate conditions to allow for a controlled burst in peroxide levels. Given the importance of Prxs both in pathogen defense and in human cells for combating oxidative stress and for cellular regulation, we propose here to expand our research program by both continuing our well-established work to elucidate the fundamental structural and biochemical aspects of catalysis by the variety of known Prxs (Specific Aims 1, 2, and 4) and by developing a novel systems biology approach to understand the relative contributions of Prxs and other peroxidases to peroxide homeostasis in eukaryotic cells (Specific Aim 3). Oxidative damage is thought to be important in aging, in the development of cancer and in many degenerative diseases. Moreover, impairments in cell signaling processes controlling proliferation, differentiation and apoptosis are associated with many disease states. An enhanced understanding of Prxs and the roles they play in both cell signaling and antioxidant protection will thus have important implications for the prevention of human diseases. In addition, the role of Prxs in protecting human pathogens against killing by the immune system implicates Prxs as targets for the development of new therapeutic agents to combat infectious diseases.