Monomers and Dimers of Cytochrome c in Apoptotic Peroxidase Activity

该奖项由化学部生命过程化学项目资助布鲁斯E.蒙大拿大学的Bowler研究了细胞色素c蛋白质三维结构的变化如何将其功能从移动电子的蛋白质改变为加速膜脂质（脂肪）与过氧化氢反应的蛋白质。后一种所谓的过氧化物酶活性在重要的生物化学途径中提供了早期信号。该项目还将为本科生和研究生提供广泛的结构、生物化学和生物物理方法方面的培训。作为该项目的一部分，Bowler博士和他的学生正在开发在低资源环境中有效的实践课程材料，以加强与米苏拉的spectrUM科学中心合作的部落学校的STEM教育。要进行的研究的假设来自一种新的X射线衍射结构的酵母异-1-细胞色素c绑定到洗涤剂CYMAL-6。在CYMAL-6的存在下，异-1-细胞色素c结晶为结构域交换的二聚体，CYMAL-6结合在口袋中，将其烃链置于血红素铁旁边。Bowler博士的实验室正在通过测量单体与二聚体细胞色素c的过氧化物酶活性来测试这种二聚体结构对过氧化物酶活性很重要的假设，确定心磷脂纳米盘催化二聚体形成的能力，并测试脂质类似物稳定二聚体的能力。结晶和不同的脂质类似物的结构研究也正在尝试更充分地定义二聚体的脂质结合口袋。这项工作是用三种进化上不同形式的细胞色素c进行的，酵母、蜘蛛猴和人类的细胞色素c。突变的脂质结合口袋附近的两个表面环的影响，结合口袋的可及性和过氧化物酶活性的细胞色素c也正在调查，以确定如何从酵母进化到人类优化细胞色素c的过氧化物酶活性。最后，细胞色素c的二聚体结构表明，一个广泛的组赖氨酸残基控制的静电结合的细胞色素c的心磷脂。正在进行细胞色素c变体与这些赖氨酸消除的结合研究，以确定细胞色素c表面上的静电对接位点的程度。

This award from the Chemistry of Life Processes Program within the Chemistry Division is funding Dr. Bruce E. Bowler from the University of Montana to investigate how changes in the three-dimensional structure of a protein known as cytochrome c changes its function from a protein that moves electron around to one that speeds up the reaction of membrane lipids (fats) with hydrogen peroxide. This latter, so-called, peroxidase activity provides an early signal in important biochemical pathways. This project will also provide training for undergraduate student and graduate students in a broad array of structural, biochemical and biophysical methods. As part of this project, Dr. Bowler and his students are developing hands-on curricular materials, effective in low resource environments, to enhance STEM education at tribal schools in collaboration with the spectrUM science center in Missoula. The hypotheses for the research to be carried out derive from a novel X-ray diffraction structure of yeast iso-1-cytochrome c bound to the detergent CYMAL-6. In the presence of CYMAL-6, iso-1-cytochrome c crystallizes as a domain-swapped dimer with CYMAL-6 bound in a pocket placing its hydrocarbon chain next to the heme iron. Dr. Bowler's lab is testing the hypothesis that this dimeric structure is important for peroxidase activity by measuring the peroxidase activity of monomeric versus dimeric cytochrome c, determining the ability of cardiolipin nanodiscs to catalyze the formation of dimer, and also testing the ability of lipid analogs to stabilize the dimer. Crystallization and structural studies with different lipid analogs also is being attempted to more fully define the lipid binding pocket of the dimer. The work is being carried out with three evolutionally diverse forms of cytochrome c, those of yeast, spider monkey and human. The effects of mutations to two surface loops near the lipid binding pocket, on the accessibility of the binding pocket and the peroxidase activity of cytochrome c also is being investigated to determine how evolution from yeast to humans has optimized cytochrome c for peroxidase activity. Finally the dimeric structure of cytochrome c indicates that a broad group of lysine residues control the electrostatic binding of cytochrome c to cardiolipin. Binding studies on cytochrome c variants with these lysines eliminated is being conducted to determine the extent of the electrostatic docking site on the surface of cytochrome c.