Collaborative Research: Bacterial manganese(IV) oxide biomineralization: Mechanism of Mn(II,III) oxidation by the multicopper oxidase complex

合作研究：细菌氧化锰（IV）生物矿化：多铜氧化酶复合物氧化锰（II，III）的机制

• 批准号: 1410353
• 负责人: Thomas Spiro
• 金额: $ 25.92万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1410353&HistoricalAwards=false
• 关键词: Collaborative; Research; Bacterial; manganese; IV

With this award, the Chemistry of Life Processes Program is funding Dr. Bradley Tebo of Oregon Health and Science University and Dr. Thomas Spiro of the University of Washington for a collaborative research investigation of how manganese is oxidized in living systems. The substances formed in this oxidation are various forms of manganese oxide. These minerals are some of the strongest oxidants found in the environment and play important roles in both a biological and a geological sense. They are often called "scavengers of the sea" because of their great ability to absorb toxic substances. The chemical details of the biological oxidation of manganese ions and formation of manganese oxides by enzymes are not yet elucidated. The research of Dr. Tebo and Dr. Spiro examines the role of a specific enzyme, multicopper manganese oxidase, or MCO, that is derived from a bacterium that lives in the ocean. In previous research, the investigators were able to isolate the enzyme and, in the process, found that additional proteins seem necessary for the manganese oxidation. The current research addresses the nature of these newly discovered "helper" proteins and the chemistry catalyzed by MCO and the helper proteins; the results can be used to shed light on how the bacterium converts manganese in seawater to the mineral exerts its important role in detoxifying seawater. The work impacts our understanding of several areas of science including oceanography, geology, biology and biochemistry. Another broad impact is through the inclusion of students at all educational levels, including high school, in the research. The investigators disseminate insights obtained from research to the general public through a science-in-art project.A collaborative approach involving the two groups from different universities is being used to study the mechanism of bacterial manganese Mn(II) oxidation and manganese oxide production by the multicopper Mn oxidase (MCO) from Bacillus sp. PL-12. The formation of manganese oxide by bacterial oxidation of dissolved Mn(II) is important in aquatic and soil environments and is a key pathway in the global Mn cycle, which supports life through the Mn catalytic centers of many enzymes. This process has received increased technological interest because it leads to highly-reactive, nanoparticulate minerals, which can break down organic molecules and adsorb other metal ions, thereby controlling the distribution and bioavailability of many toxic and essential elements. An interdisciplinary effort using tools from chemistry, biochemistry and biophysics is being used to elucidate the mechanism of manganese oxidation by MCO. The biochemical mechanism by which this oxidation, as well as MnO2 mineralization, occurs is poorly understood. Multicopper oxidase enzymes have been implicated as catalysts for the Mn(II) oxidation in many model systems for Mn(II)-oxidizing bacteria, including the recently purified Mn oxidase complex from Bacillus sp. PL-12. In this project, the structure and mechanism by which the Mn oxidase complex from Bacillus sp. carries out two sequential one-electron oxidation steps and mineralize Mn is being elucidated. The specific objectives of the research are: 1) to characterize the copper centers of the Mn oxidase complex; 2) to determine the course of Mn oxidation and oxygen entry; 3) to characterize polynuclear intermediates formed on the pathway to MnO2; 4) to describe the role of ancillary proteins required for the expression of the active complex; and 5) to elucidate the structure of the enzyme complex and emerging oxides. X-ray crystallography and spectroscopic methods are being used in conjunction with basic biochemistry techniques to achieve these objectives.

有了这个奖项，生命过程化学项目资助俄勒冈健康与科学大学的Bradley Tebo博士和华盛顿大学的Thomas Spiro博士合作研究锰在生命系统中是如何氧化的。在这种氧化过程中形成的物质是各种形式的氧化锰。这些矿物质是在环境中发现的最强氧化剂，在生物和地质意义上都起着重要作用。它们通常被称为“海洋清道夫”，因为它们吸收有毒物质的能力很强。锰离子生物氧化和酶生成锰氧化物的化学细节尚未阐明。特博博士和斯皮罗博士的研究考察了一种特殊的酶——多铜锰氧化酶（MCO）的作用，这种酶来自一种生活在海洋中的细菌。在之前的研究中，研究人员能够分离出这种酶，并在此过程中发现，锰氧化似乎需要额外的蛋白质。目前的研究解决了这些新发现的“辅助”蛋白的性质和MCO和辅助蛋白催化的化学；这些结果可以用来揭示细菌如何将海水中的锰转化为矿物质，在海水解毒中发挥重要作用。这项工作影响了我们对几个科学领域的理解，包括海洋学、地质学、生物学和生物化学。另一个广泛的影响是通过将包括高中在内的所有教育水平的学生纳入研究。研究人员通过艺术科学项目向公众传播从研究中获得的见解。来自不同大学的两个小组正在采用合作方法研究芽孢杆菌sp. PL-12的多铜锰氧化酶（MCO）对细菌锰锰（II）氧化和锰氧化物生产的机制。细菌氧化溶解的锰（II）形成氧化锰在水生和土壤环境中是重要的，并且是全球锰循环的关键途径，通过许多酶的锰催化中心支持生命。这一过程已经获得了越来越多的技术兴趣，因为它可以产生高活性的纳米颗粒矿物，这些矿物可以分解有机分子并吸附其他金属离子，从而控制许多有毒元素和必需元素的分布和生物利用度。利用化学、生物化学和生物物理学的工具，一项跨学科的努力正在被用来阐明锰被MCO氧化的机制。这种氧化以及MnO2矿化发生的生化机制尚不清楚。在许多Mn（II）氧化细菌的模型系统中，多铜氧化酶被认为是Mn（II）氧化的催化剂，包括最近从芽孢杆菌sp. PL-12中纯化的Mn氧化酶复合物。本课题研究了芽孢杆菌中锰氧化酶复合体的结构和机制，该复合体通过两个连续的单电子氧化步骤来矿化锰。本研究的具体目的是：1)表征Mn氧化酶复合物的铜中心；2)确定Mn的氧化过程和氧的进入；3)表征生成MnO2途径上形成的多核中间体；4)描述活性复合物表达所需的辅助蛋白的作用；5)阐明酶配合物的结构和新出现的氧化物。x射线晶体学和光谱学方法正在与基本的生物化学技术相结合，以实现这些目标。