JBIC Journal of Biological Inorganic Chemistry ( IF 2.7 ) Pub Date : 2020-09-14 , DOI: 10.1007/s00775-020-01820-0 Francesco Musiani 1 , Valquiria Broll 1 , Elisa Evangelisti 1 , Stefano Ciurli 1
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Abstract
Ammonia monooxygenase is a copper-dependent membrane-bound enzyme that catalyzes the first step of nitrification in ammonia-oxidizing bacteria to convert ammonia to hydroxylamine, through the reductive insertion of a dioxygen-derived O atom in an N–H bond. This reaction is analogous to that carried out by particulate methane monooxygenase, which catalyzes the conversion of methane to methanol. The enzymatic activity of ammonia monooxygenase must be modulated to reduce the release of nitrogen-based soil nutrients for crop production into the atmosphere or underground waters, a phenomenon known to significantly decrease the efficiency of primary production as well as increase air and water pollution. The structure of ammonia monooxygenase is not available, rendering the rational design of enzyme inhibitors impossible. This study describes a successful attempt to build a structural model of ammonia monooxygenase, and its accessory proteins AmoD and AmoE, from Nitrosomonas europaea, taking advantage of the high sequence similarity with particulate methane monooxygenase and the homologous PmoD protein, for which crystal structures are instead available. The results obtained not only provide the structural details of the proteins ternary and quaternary structures, but also suggest a location for the copper-containing active site for both ammonia and methane monooxygenases, as well as support a proposed structure of a CuA-analogue dinuclear copper site in AmoD and PmoD.
Graphic abstract
中文翻译：
铜依赖性氨单加氧酶的模型结构。
摘要
氨单加氧酶是一种铜依赖性的膜结合酶，通过还原性地在N–H键中插入源自双氧的O原子，催化氨氧化细菌中硝化的第一步，将氨转化为羟胺。该反应类似于由颗粒甲烷单加氧酶进行的反应，该酶催化甲烷向甲醇的转化。必须调节氨单加氧酶的酶促活性，以减少用于作物生产的氮基土壤养分释放到大气或地下水中，这种现象已知会大大降低初级生产的效率并增加空气和水的污染。氨单加氧酶的结构不可用，因此无法合理设计酶抑制剂。欧洲亚硝化单胞菌，利用与颗粒甲烷单加氧酶和同源PmoD蛋白的高序列相似性，替代地可获得晶体结构。获得的结果不仅提供了蛋白质三元和四元结构的结构细节，而且还为氨和甲烷单加氧酶的含铜活性位点提供了位置，并支持了拟议的CuA-类似物双核铜的结构。 AmoD和PmoD中的网站。
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