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质，它们作为氧化还原酶或电子载体在所有生命界生物的各种代谢途径中发挥着重要作用。其中，亚型c的特征在于辅因子血红素与蛋白质链的共价连接。细胞色素c通常含有大量与蛋白质链相关的辅因子，并且在细菌代谢途径中发挥关键作用，无论是作为电子载体还是作为氧化还原酶。因此，辅因子的排列显示了不同蛋白质之间血红素包装的重复动机，即使在没有任何可检测的序列同源性的情况下。这些堆积动机在进化上是保守的，显然具有功能意义，但由于多金属中心的强耦合，它们的性质很难用光谱方法研究。为了便于功能分析，我们已经着手确定可能的二血模型系统血红素血红素相互作用的动机，从细胞色素c丰富的基因组的Geclampus sulfurreducens或其亲属，可访问的突变研究，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，确定了它的晶体结构，并开始光谱分析。在这里，我们提出了进一步确定和表征合适的模型蛋白质，并分析其性质的系统，突变的研究相关光谱学，电化学和晶体学分析。从简单的模型系统，我们希望发展一个基本的理解血红素相互作用，并随后将这一知识转移到更大，更复杂的蛋白质。