Mechanisms of Energy Conservation in Bifurcating Electron Transfer Flavoproteins

分叉电子转移黄素蛋白的能量守恒机制

基本信息

批准号：
1808433
负责人：
Anne-Frances Miller
金额：
$ 47.1万
依托单位：
University of Kentucky Research Foundation
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2018
资助国家：
美国
起止时间：
2018-07-01 至 2021-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1808433&HistoricalAwards=false
关键词：
Mechanisms Energy Conservation Bifurcating Electron

项目摘要

Just as electrical wires carry power to every room in our houses, cells have dedicated proteins carrying a current of electrons from reactions that generate electrons to vital reactions that require them. This project addresses a newly-recognized class of 'electron transferring flavoproteins' (Etfs) that act as energy brokers, trading quantity for quality by accepting pairs of modest-energy electrons and concentrating their energy onto just one of the pair to produce one high-energy electron. Crucially, this biochemical 'step-up station' makes it possible for cells to fix nitrogen gas from air to generate their own fertilizer, making food production possible where it otherwise would not be. The project seeks to understand HOW these Etfs accomplish this complex process. The research seeks to learn what is special about the site at which energy is reallocated among the two electrons by studying the molecule on which this happens (this flavin is a derivative of the riboflavin vitamin B2). The research also seeks to identify safety mechanisms built into the protein scaffold that allow such demanding transformations to occur within a benign, non-toxic protein. Thus the work aims to articulate the underlying principles of the process, so that they can be designed into human-made devices and materials, to increase our ability to use solar power and boost the efficiency and versatility with which we use electrical energy in general. Flavins are just one example of many plant pigments that present powerful chemical properties along with glorious colors. The project scientists share their enthusiasm for pigments via a series of workshops and a course on plant pigments, fibers and fragrances in which participants create a fiber art project using natural materials while learning about the chemical principles underlying plant colors. This creative chemistry course gives all participants a chance to design experiments and integrate science and art.A long-familiar family of proteins has recently been found to have a surprising capacity to re-allocate energy among pairs of electrons acquired from NADH, yielding one with more reducing power than the NADH source (electron transfer bifurcation, or 'bifurcation'). This research establishes which of the two flavins plays which of the contrasting roles identified in the newly-purified bifurcating electron transferring flavoprotein (Etf), and then seeks to understand what aspects of the protein environment are responsible for each of the different activities (conventional electron transfer vs. bifurcation). Spectroelectrochemical titrations measure the extent to which individual amino acids change the flavin reduction potentials (Eo) in proteins bearing amino acid substitutions, and spectroscopic studies elucidate changes in flavin covalent bonding, hydrogen bonding and protonation states, mapping out the active site's role in producing bifurcating activity. Residues to be targeted include a cysteine common to all the Etfs associated with nitrogen fixation but not conserved in others. Thus the research may reveal the protein context needed in order to exploit flavins' capacity for this reactivity while suppressing side-effects. The objective is to elucidate principles underlying the versatility and efficiency of bifurcation, for implementation beyond biochemistry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

就像电线为我们房屋中的每个房间携带动力一样，细胞也具有专用蛋白质，这些蛋白质带有来自反应的电流，这些反应会产生电子到需要它们的重要反应。该项目介绍了新认可的一类“电子转移黄蛋蛋白”（ETF），该类别充当能源经纪人，通过接受一对适中的能量电子并将其能量集中到其中一对以产生一个高能量电子，从而将质量交易数量用于质量。至关重要的是，这个生化的“加速站”使细胞可以从空气中固定氮气来产生自己的肥料，从而使粮食生产成为可能。该项目试图了解这些ETF如何完成这一复杂过程。该研究试图通过研究发生这种情况的分子（该黄素是核黄素维生素B2的衍生物），了解两个电子中能量在两个电子中重新分配的地方的特殊之处。该研究还旨在确定蛋白质支架内置的安全机制，使这种苛刻的转化发生在良性的无毒蛋白质中。因此，这项工作旨在阐明该过程的基本原理，以便可以将它们设计到人造的设备和材料中，以提高我们使用太阳能并提高我们使用电能的效率和多功能性的能力。黄素只是许多植物色素的一个例子，它们具有强大的化学特性以及光荣的颜色。该项目科学家通过一系列研讨会以及有关植物色素，纤维和香水的课程分享了他们对颜料的热情，参与者使用天然材料创建纤维艺术项目，同时了解植物颜色的化学原理。该创意化学课程使所有参与者都有设计实验并整合科学和艺术的机会。最近发现，长期熟悉的蛋白质家族具有令人惊讶的能力，可以重新分配从NADH获得的电子成对的能量，从而产生比NADH源更低的能力（电子转移bifurcation Bifurcation，或'Bifurcation，或'Bifurcation'）。这项研究确定了两种黄素中的哪种扮演哪个在新纯化的分叉电子转移黄皮蛋白（ETF）中确定的对比作用，然后试图了解蛋白质环境的哪些方面是造成每种不同活性的原因（常规电子转移与传统电子转移）。光谱电化学滴定测量单个氨基酸在带有氨基酸取代的蛋白质中改变黄素还原电位（EO）的程度，以及光谱研究阐明了黄素共价键合，氢键和原质粘合状态的变化，从而绘制了活跃部位在活跃部位产生的生物生产活性的作用。靶向靶向的残留物包括与氮固定相关的所有ETF共有的半胱氨酸，但在其他ETF中不保守。因此，该研究可能揭示了为了在抑制副作用的同时利用黄素的能力来利用黄素的能力所需的蛋白质环境。目的是阐明分叉的多功能性和效率的基本原则，以实施超越生物化学。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子优点和更广泛影响的评估来评估的审查标准。