Functional Implications of Heme-packing Motives in c-type Cytochromes

c 型细胞色素中血红素包装基序的功能意义

• 批准号: 5451573
• 负责人: Professor Dr. Oliver Einsle
• 金额: --
• 依托单位: Institut für Biochemie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2005
• 资助国家: 德国
• 起止时间: 2004-12-31 至 2007-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5451573?language=en
• 关键词: Functional; Implications; Heme; packing; Motives

Cytochromes are ubiquitous metalloproteins that play an essential role as redox enzymes or electron carriers in various metabolic pathways of organisms from all kingdoms of life. Among them, the subtype c is characterized by a covalent attachment of the cofactor heme to the protein chain. Cytochromes c often contain a large number of cofactors relative to the protein chain and play crucial roles in bacterial metabolic pathways, either as electron carriers or as redox enzymes. Hereby the arrangement of cofactors shows recurring motives of heme packing among different proteins, even in the absence of any detectable sequence homology. Being evolutionarily con-served, these packing motives are obviously of functional significance, but due to the strong cou-pling of multiple metal centers their properties are difficult to investigate using spectroscopic methods. In order to facilitate functional analyses we have set out to identify possible dihemic model systems for heme-heme interaction motives from the cytochrome-c-rich genome of Geobacter sulfurreducens or its relatives which are accessible to mutational studies and have interpretable spectroscopic properties. We have obtained a first model system, DHC2, determined its crystal structure and initiated spectroscopic analyses. Here we propose to identify and characterize further suitable model proteins and analyze their properties in a systematic, mutational study correlating spectroscopy, electrochemistry and crystallographic analysis. From simple model systems we want to develop a fundamental understanding of heme interaction and subsequently transfer this knowl-edge to larger and more complex proteins.

细胞色素是普遍存在的金属蛋白，在所有生命领域的生物体的各种代谢途径中作为氧化还原酶或电子载体发挥着重要作用。其中，c亚型的特点是辅因子血红素与蛋白质链共价连接。细胞色素 c 通常含有大量与蛋白质链相关的辅助因子，在细菌代谢途径中发挥着至关重要的作用，无论是作为电子载体还是作为氧化还原酶。因此，即使没有任何可检测到的序列同源性，辅助因子的排列也显示了不同蛋白质之间血红素堆积的重复动机。由于进化上保守，这些堆积动机显然具有功能意义，但由于多个金属中心的强耦合，它们的性质很难使用光谱方法进行研究。为了促进功能分析，我们已经着手从硫还原地杆菌或其亲属的富含细胞色素c的基因组中识别血红素-血红素相互作用动机的可能的二向模型系统，这些系统可用于突变研究并具有可解释的光谱特性。我们已经获得了第一个模型系统 DHC2，确定了其晶体结构并开始了光谱分析。在这里，我们建议进一步鉴定和表征合适的模型蛋白质，并在与光谱学、电化学和晶体学分析相关的系统突变研究中分析其特性。我们希望从简单的模型系统出发，对血红素相互作用有一个基本的了解，然后将这些知识转移到更大、更复杂的蛋白质上。