Collaborative Research: Understanding Electron Bifurcation in Methanogenic Archaea

有了这个奖项，生命过程化学计划资助奥本大学的埃弗特·杜因博士和华盛顿大学的约翰·利博士研究电子分岔的重要过程，这发生在生命系统将能量从一种形式转化为另一种形式时。在这个过程中，两个电子以相同的电势进入系统，但当它们离开时，其中一个的电势比另一个低得多。因此，电子分叉使得生物分子的上坡、高耗能的电子还原成为可能，因为伴随而来的是下坡氧化，从而平衡了能量消耗和生成。这一过程已经在生产生物燃料的古生菌产生和消耗甲烷的功能中被观察到，但也在其他形式的生命中被观察到，包括我们自己的身体。了解这一过程的工作原理可能有助于改善沼气的生产或帮助优化甲烷向生物柴油的转化，并有助于我们回答各种与健康有关的问题。这项研究对所有教育水平的学生成为下一代科学家的准备工作产生了更广泛的影响。该项目的合作性质涉及来自美国不同地理区域的小组，为学生获得跨学科和合作研究的技能创造了一个环境。电子分叉使酶能够通过同时产生具有高氧化还原电位的电子来产生具有极低氧化还原电位的电子。这消除了将前电子转移步骤与ATP水解相耦合的需要。分叉过程中总是包含一个醌或黄素基团。Duin和Leigh小组将研究氢化酶：异二硫还原酶复合物的电子分岔，它在铁硫簇中含有铁离子。该理论认为，一些铁硫簇在电子分岔过程中发挥了重要作用，它们向中心黄素提供电子，然后接受高电位或低电位电子。位点直接诱变将用于改变铁硫簇和黄素及其直接环境。这些变化对团簇和黄素的电子和磁性能的影响将通过吸收、电子顺磁共振和磁圆二色光谱来评估，分岔过程将通过确定团簇和黄素的氧化还原特性和氧化还原过程的动力学来检查。

With this award, the Chemistry of Life Processes Program is funding Dr. Evert Duin of Auburn University and Dr. John Leigh of the University of Washington to study the important process of electron bifurcation, which occurs when living systems convert energy from one form to another. In this process, two electrons enter the system with identical potential, but when they exit, one has a much lower potential than the other. Consequently, electron bifurcation makes possible an uphill, energy-demanding, electron reduction of a biological molecule because a downhill oxidation occurs concomitantly, which balances the energy consumption and generation. The process has been observed in the methane-producing and -consuming functions of Archaea, which produce biofuels, but also in other forms of life, including our own bodies. Understanding how this process works could be beneficial for improving the production of biogas or helping to optimize the conversion of methane to biodiesel and could help us answer a variety of health-related questions. The research has a further broader impact on the preparation of students at all educational levels to become the next generation of scientists. The collaborative nature of the project that involves groups from different geographic regions of the United States creates an environment in which the students acquire skills for interdisciplinary and collaborative research.Electron bifurcation enables enzymes to create electrons with a very low redox potential by simultaneously creating an electron with a high redox potential. This eliminates the need to couple the former electron transfer step to ATP hydrolysis. The bifurcation process always involves a quinone or flavin group. The Duin and Leigh groups will study the electron bifurcation by the hydrogenase:heterodisulfide reductase complex, which contains iron ions within iron-sulfur clusters. The theory is that some of the iron-sulfur clusters play an important part in the electron bifurcation process by donating electrons to the central flavin and then accepting either the high or low potential electrons. Site-direct mutagenesis will be used to make changes to the iron-sulfur clusters and to the flavins and their direct environment. The consequences of these changes on the electronic and magnetic properties of the clusters and flavins will be evaluated by absorption, electron paramagnetic resonance, and magnetic circular dichroism spectroscopies and the bifurcation process will be examined by determining the redox properties of the clusters and flavins and the kinetics of the redox processes.