The Evolutionary Origin and Potential of Newly Recruited Enzymes

新招募的酶的进化起源和潜力

• 批准号: 7808743
• 负责人: SHELLEY D. COPLEY
• 金额: $ 28.9万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7808743
• 关键词: Active Sites; Address; Affect; Agriculture; Animal Model; Antibiotic Resistance; Antibiotics; Bacteria; Benign; Binding; Biochemical; Bioremediations; Catalysis; Cells; Chemicals; Chlorine; Cleaved cell; Degradation Pathway; Development; Dioxygenases; Elements; Engineering; Enzymes; Escherichia coli; Evolution; Family; Genetic; Genomics; Glutathione; Household; Human; Hydrogen; Hydroxylation; Industry; Iron; Knowledge; Life; Metabolic Pathway; Methods; Microbe; Mutation; Outcome; Oxidoreductase; Pathway interactions; Pentachlorophenol; Pentachlorophenol monooxygenase; Pharmacologic Substance; Phenol 2-monooxygenase; Play; Process; Proteins; Quinone Reductases; Reaction; Recruitment Activity; Resistance; Role; Scientist; Soil; Source; Staging; Structure; Sulfur; System; Toxin; Work; catalyst; chemical reaction; chemical release; dehalogenation; design; enzyme activity; improved; interest; member; microorganism; novel; pollutant; protein structure function; public health relevance

DESCRIPTION (provided by applicant): The evolution of enzymes was a critical element of the emergence of life on Earth and its subsequent divergence to occupy a vast range of ecological niches. Most enzymes have impressive catalytic capabilities that have been honed over 3.8 billion years of evolution. We are interested in the early stages of evolution of new enzymes. This application addresses enzymes that appear to have been recently recruited to serve new functions in the pathway for degradation of pentachlorophenol (PCP) in Sphingobium chlorophenolicum, a bacterium isolated from soil heavily contaminated with PCP. S. chlorophenolicum appears to have patched together a poorly functioning pathway for degradation of PCP using enzymes from at least two previously existing pathways. This experimental system provides us with a window on the evolution of a new metabolic pathway at a very early stage in the process. This application focuses on the initial three enzymes in the pathway that limit the flux through the PCP degradation pathway. PCP hydroxylase catalyzes the hydroxylation of PCP to form the toxic intermediate, tetrachlorobenzoquinone (TCBQ). TCBQ reductase catalyzes the reduction of TCBQ to tetrachlorohydroquinone (TCHQ). TCHQ dehalogenase catalyzes two successive reductive dehalogenation reactions that remove chlorines, allowing the ring to be cleaved. Our aims are 1) to obtain structures of PCP hydroxylase and TCHQ dehalogenase; 2) to explore the evolutionary origin and a possible additional function of TCBQ reductase; 3) to evolve improved versions of all three enzymes; and 4) to determine how the improved enzymes affect the ability of the bacterium to degrade PCP. The outcome of this work will be a better understanding of the sources from which new enzymes can arise, and the quality of catalysis achieved during the initial stages of evolution of a new enzyme. PUBLIC HEALTH RELEVANCE: We will better understand the prospects for evolution of pathways to degrade toxic pollutants and the problems associated with development of antibiotic resistance by recruitment of enzymes that detoxify antibiotics. In addition, this work will inform efforts to engineer enzymes and bacteria to produce chemicals and pharmaceuticals or to degrade pollutants under environmentally benign conditions.

描述(申请人提供)：酶的进化是地球上生命出现及其随后的分化占据广泛的生态位的关键因素。大多数酶都具有令人印象深刻的催化能力，这种能力经过38亿年的进化而得到磨练。我们对新酶进化的早期阶段很感兴趣。这项申请涉及的酶似乎是最近招募的，在降解五氯酚(PCP)的途径中发挥新功能的Sphingobium氯苯酚，这是一种从被PCP严重污染的土壤中分离出来的细菌。氯苯硫杆菌似乎利用至少两条先前存在的途径中的酶，拼接了一条功能不佳的降解五氯苯酚的途径。这个实验系统为我们提供了一个窗口，在这个过程的非常早期阶段就进化出一种新的代谢途径。这一应用主要集中在限制通过PCP降解途径的通量的途径中的最初三种酶。PCP羟基酶催化PCP羟基化生成有毒中间体四氯苯醌(TCBQ)。TCBQ还原酶催化四氯对苯二酚(TCHQ)的还原。TCHQ脱卤酶催化两个连续的还原脱卤化反应，去除氯，使环被裂解。我们的目标是1)获得PCP羟基酶和TCHQ脱卤酶的结构；2)探索TCBQ还原酶的进化起源和可能的额外功能；3)进化这三种酶的改进版本；以及4)确定改进的酶如何影响细菌降解PCP的能力。这项工作的结果将是更好地了解新酶可以产生的来源，以及在新酶进化的初始阶段所实现的催化质量。与公共卫生相关：我们将更好地了解降解有毒污染物的途径的演变前景，以及通过补充解毒抗生素的酶来发展抗生素耐药性所带来的问题。此外，这项工作将为设计酶和细菌以生产化学品和药品或在环境友好的条件下降解污染物的努力提供信息。