Control of Sulfite Reductase Activity via Structural Flexibility and a Push-Pull Mechanism for Electron Transfer

这项工作旨在通过探索一种称为亚硫酸盐还原酶的酶的结构和功能，发现细菌如何代谢硫的基本机制。由于美国南部最近发生的洪水，商业养猪场的有毒硫副产品进入环境，造成环境污染，因此这一主题特别重要。该提案将有助于培养本科生和研究生水平的研究人员在科学方法和技术，其中实验室擅长。这些实验的结果将为我们了解硫代谢的基础科学提供信息，并为有毒硫化合物的生物修复技术进步提供见解。本提案中概述的实验旨在回答三个问题：1）亚硫酸盐还原酶如何作为大分子氧化还原酶机器发挥作用？2)两个亚硫酸还原酶亚基如何相互作用以允许有效的六电子转移？3)质子从哪里来平衡电子转移反应？该实验将使用各种生物物理技术，包括小角中子散射，中子衍射，X射线衍射和低温电子显微镜，以全面分析这种酶所采用的复杂相互作用和构象。该奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

This work aims to discover fundamental mechanisms for how bacteria metabolize sulfur by exploring the structure and function of an enzyme known as sulfite reductase. The topic is of particular importance owing to the rise of environmental pollution in the form of toxic sulfur byproducts from commercial pig farms that leech into the environment due to recent flooding in the southern United States. The proposal will help train undergraduate and graduate-level researchers in the scientific methods and techniques in which the laboratory excels. The results from these experiments will inform our understanding of the basic science of sulfur metabolism as well as provide insights into technological advances in bioremediation of toxic sulfur compounds. The experiments outlined in this proposal aim to answer three questions: 1) how does sulfite reductase function as a macromolecular oxidoreductase machine? 2) how do the two sulfite reductase subunits interact to allow for efficient six electron transfers? 3) from where do the protons come to balance the electron transfer reactions? The experiments will use a variety of biophysical techniques, including small angle neutron scattering, neutron diffraction, X-ray diffraction, and cryogenic electron microscopy to comprehensively analyze the complex interactions and conformations this enzyme adopts.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.