Biochemistry of the Anaerobic Dehalogenation of Chlorinated Aromatics

这项研究着眼于一种可以解毒卤代有机污染物（如多氯联苯）的微生物，即Desulfitobacteria。多氯联苯被列为“十二种肮脏的”持久性有机污染物（POP），虽然被禁止，但仍存在于环境中，对动物健康和环境造成持久的损害。长期目标是帮助实现2001年联合国条约关于逐步淘汰并最终消除这些持久性有机污染物的目标。因此，更好地了解如何加速这些化合物的自然生物降解将对社会具有重要价值。通过一个被称为脱盐呼吸的过程，这些微生物在获得代谢能量的同时生物降解卤化化合物。当脱硫菌感知到卤化化合物的存在时，它们会产生一系列蛋白质，使它们能够去除氯取代基，这是其解毒的第一步。多种技术被用于研究脱盐呼吸，包括酶学、分子生物学和遗传学、光谱学和电化学。本项目的第一个目的是阐明脱卤酶的催化机理，去除氯取代基。为了实现这一目标，将阐明脱卤酶催化循环中的每个步骤，并确定金属辅助因子（维生素B12和铁硫簇）的作用。第二个目标是研究转录调节蛋白（CprK），该蛋白控制何时以及产生多少脱盐呼吸蛋白。当CprK结合卤化化合物的稀释溶液时，它附着在特定的DNA调控序列上，并加速脱盐呼吸系统成分的生产速度。转录调节蛋白（CprK）与异种生物之间以及CprK与DNA序列之间的相互作用将被研究。该项目还包括促进教学、培训和学习的计划；加强内布拉斯加大学的研究基础设施；并广泛传播研究成果。

This study looks at a genus of microbes, Desulfitobacteria, that can detoxify halogenated organic pollutants such as polychlorinated biphenyls (PCBs). PCBs are listed as a "dirty dozen" persistent organic pollutant (POP) that, although banned, remain in the environment and cause lasting damage to animal health and the environment. The long-term goal is to help achieve the aim of a 2001 United Nations treaty to phase out and eventually eliminate these POPs. Thus a better understanding of how to accelerate the natural biodegradation of such compounds would be of significant value to society. Through a process known as dehalorespiration, these microbes biodegrade halogenated compounds while gaining metabolic energy. When Desulfitobacteria sense the presence of a halogenated compound, they produce a host of proteins that enable them to remove the chlorine substituent, which is the first step in its detoxification. A manifold of techniques are used to study dehalorespiration, including enzymology, molecular biology and genetics, spectroscopy, and electrochemistry. The first objective of this project is to elucidate the catalytic mechanism of the dehalogenase enzyme, which removes the chlorine substituent. To achieve this aim, each of the steps in the dehalogenase catalytic cycle will be elucidated and the role of the metal cofactors (vitamin B12 and the iron-sulfur clusters) will be determined. The second objective is to study the transcriptional regulatory protein (CprK) that controls when and how much of the dehalorespiration proteins are produced. When CprK binds dilute solutions of the halogenated compound, it attaches to a specific DNA regulatory sequence and accelerates the rate of production of the components of the dehalorespiration system. Interactions between the transcriptional regulatory protein (CprK) and the xenobiotic and between CprK and the DNA sequence will be studied. This project also includes plans to promoting teaching, training and learning; to enhance the University of Nebraska research infrastructure; and to broadly disseminate the research results.