Comparative Heme Metabolism in Divergent Eukaryotes

不同真核生物中血红素代谢的比较

• 批准号: 10404110
• 负责人: Paul A Sigala
• 金额: $ 38.13万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10404110
• 关键词: Apoptosis; Binding; Biochemical; Biogenesis; Biological; Cells; Chemistry; Comparative Study; Defect; Electron Transport; Enzymes; Erythrocytes; Eukaryota; Eukaryotic Cell; Goals; Heme; Human; Invaded; Mediating; Metabolism; Mitochondria; Mitochondrial Matrix; Molecular; Oxidation-Reduction; Parasites; Peroxidases; Plasmodium; Play; Production; Property; Research; Respiration; Role; Signal Transduction; Site; Structure; Testing; Toxic effect; Work; cofactor; comparative; cytochrome c; emerging pathogen; heme-binding protein; human disease; human pathogen; insight; mitochondrial dysfunction; pathogen; pathogenic microbe; programs; thioether; three dimensional structure; trafficking

PROJECT SUMMARY/ABSTRACT Heme is an ancient biological cofactor that plays critical roles in mitochondrial redox chemistry, energy production, and signaling in all eukaryotic cells from humans to microbial pathogens. Despite functional similarities in their reliance on heme, divergent eukaryotes have evolved distinct molecular adaptations that tune heme metabolism to particular cellular demands. Comparing and contrasting key features of mitochondrial heme metabolism can thus reveal general principles in heme trafficking and utilization, as well as unveil unique adaptations that highlight the evolutionary diversity among eukaryotes. Elucidating these general principles will increase understanding of heme-related mitochondrial dysfunctions that underpin major human diseases. Understanding of functional differences in heme metabolism can be exploited to develop new pathogen-specific therapies that avoid human toxicity. In this proposal, we lay out a long-term goal of our research program to deeply understand key biochemical properties and mechanisms of mitochondrial heme metabolism in humans and a major human pathogen. In pursuing this goal over the next five years, we will focus our studies on understanding the molecular mechanisms of biogenesis and function of cytochrome c, a critical and tractable heme-binding protein with major unresolved mechanistic features that exemplifies key features of mitochondrial heme metabolism and its conservation as well as diversity between eukaryotes. Cytochrome c has a conserved essential function in the mitochondrial electron transport chain (ETC) but also plays an important, separate role as a peroxidase that signals the onset of apoptosis. The molecular features of cytochrome c that underpin its functional transition from ETC to peroxidase activity remain sparsely defined. Cytochrome c is distinguished from other heme-binding proteins by its use of a conserved CXXCH sequence motif to covalently bind heme via stable thioether bonds. This covalent attachment requires the mitochondrial intermembrane space (IMS) enzyme, holo cytochrome c synthase (HCCS). Although HCCS function is fundamental to all eukaryotic respiration, the structure of HCCS is unknown and thus molecular insight into its mechanism of attaching heme to cytochrome c is lacking. Furthermore, it remains unknown how heme is trafficked to HCCS in the IMS from its site of synthesis within the mitochondrial matrix. We propose comparative studies between human cells and Plasmodium parasites that invade heme-rich human erythrocytes to tackle the following key challenges: 1) to define the molecular features of cytochrome c that mediate its transition between ETC and peroxidase activities; 2) to elucidate the three-dimensional structure of HCCS and unravel its molecular mechanism of heme attachment to cytochrome c; and 3) to determine the mechanism of heme acquisition by HCCS. This work will advance fundamental understanding of mitochondrial heme metabolism in humans and a critical human pathogen and provide a platform for longer-term integrative studies of heme metabolism that will test and extend the lessons learned from our initial focus on cytochrome c.

项目摘要/摘要 血红素是一种古老的生物辅因子，在线粒体氧化还原化学、能量等方面起着关键作用。 从人类到微生物病原体的所有真核细胞的生产和信号传递。尽管功能强大 在依赖血红素方面的相似之处，不同的真核生物进化出了不同的分子适应 血红素代谢以满足特定的细胞需求。比较和对比线粒体亚铁血红素的主要特征 因此，新陈代谢可以揭示血红素运输和利用的一般规律，也可以揭示独特的 突出真核生物进化多样性的适应。阐明这些一般原则将会 增加对与血红素相关的线粒体功能障碍的了解，这些功能障碍是人类主要疾病的基础。 对血红素代谢功能差异的了解可以被用来开发新的病原体特异性 避免人体毒性的疗法。在这份提案中，我们列出了我们研究计划的长期目标 深入了解线粒体血红素代谢的关键生化特性和机制 也是人类的一种主要病原体。在未来五年实现这一目标时，我们将把重点放在 细胞色素c的生物发生和功能的分子机制研究 易处理的血红素结合蛋白，具有主要的未解决的机制特征，体现了 真核生物间线粒体血红素代谢及其保守性和多样性。细胞色素c有 线粒体电子传输链(ETC)中保守的基本功能，但也发挥着重要的作用， 作为过氧化物酶的单独作用，发出细胞凋亡开始的信号。细胞色素c的分子特征 支持其从ETC到过氧化物酶活性的功能转换的定义仍然很少。细胞色素c是 与其他血红素结合蛋白不同的是，它使用保守的CXXCH序列基序来共价 通过稳定的硫醚键结合血红素。这种共价连接需要线粒体膜间间隙 (IMS)酶，全息细胞色素c合成酶(HCCS)。尽管HCCS功能是所有真核生物的基础 呼吸作用，HCCS的结构尚不清楚，因此对其附着血红素的机制的分子洞察 对细胞色素c缺乏。此外，尚不清楚血红素是如何从ITS贩运到IMS中的HCCS的 线粒体基质中的合成部位。我们建议对人类细胞和 侵入富含血红素的人红细胞的疟原虫，以应对以下关键挑战：1) 确定细胞色素c在ETC和过氧化物酶活性之间传递的分子特征； 2)阐明HCCS的三维结构，揭示其与血红素作用的分子机制 与细胞色素c的结合；3)确定HCCS获取血红素的机制。这项工作将 对人类和一个关键人类线粒体血红素代谢的基础研究进展 病原体，并为测试和扩展血红素代谢的长期综合研究提供平台 从我们最初对细胞色素c的关注中吸取的教训。