Particulate methane monooxygenase

描述(申请人提供)：甲烷营养细菌利用甲烷作为其唯一的碳和能源来源。其代谢途径的第一步是甲烷单加氧酶(MMO)系统将甲烷氧化为甲醇。在甲烷排放量增加的时代，作为唯一的生物甲烷汇，甲烷氧化菌是缓解全球变暖对人类健康有害影响的潜在手段。此外，甲烷氧化菌可以氧化甲烷以外的底物，包括卤代烃，并已成为生物修复应用的目标。自然界中最主要的MMO是颗粒甲烷单加氧酶(PMMO)，它是一种低聚的、完整的膜金属酶。该项目的长期目标是了解pMMO及其同系物是如何激活O2以氧化甲烷和其他底物的。尽管最近发现了pMMO活性部位，但围绕pMMO结构和功能的主要问题仍有待解决。拟议的研究将集中于阐明铜活性中心的原子结构，氧化甲烷的活性物种的性质，底物、产物和还原剂结合位置的细节，以及跨膜结构域的作用。此外，还将对独特的pMMO同系物进行表征。实验方法涉及天然pMMO、重组pMMO、重组pMMO亚单位和结构域以及相关酶的重组结构域的光谱、机理、生化和结晶学表征。

DESCRIPTION (provided by applicant): Methanotrophic bacteria utilize methane as their sole source of carbon and energy. The first step in their metabolic pathway is the oxidation of methane to methanol by methane monooxygenase (MMO) enzyme systems. As the only biological methane sink in an era of increased methane emissions, methanotrophs are a potential means to mitigate the deleterious effects of global warming on human health. In addition, methanotrophs can oxidize substrates besides methane, including halogenated hydrocarbons, and have been targeted for bioremediation applications. The predominant MMO in nature is particulate methane monooxygenase (pMMO), an oligomeric, integral membrane metalloenzyme. The long term goal of this project is to understand how pMMO and its homologs activate O2 for oxidation of methane and other substrates. Despite the recent identification of the pMMO active site, major questions surrounding pMMO structure and function remain to be addressed. The proposed research will focus on elucidating the atomic structure of the copper active site, the nature of the reactive species that oxidizes methane, the details of substrate, product, and reductant binding sites, and the role of the transmembrane domains. In addition, characterization of unique pMMO homologs will be pursued. The experimental approach involves spectroscopic, mechanistic, biochemical, and crystallographic characterization of native pMMO, recombinant pMMO, recombinant pMMO subunits and domains, and recombinant domains from related enzymes.