Endomembrane Structure and Function Research Group, Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, OX3 0BP, UK.
Molecular Microbiology Research Group, Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield, S1 1WB, UK.
Sci Rep. 2023 Sep 15;13(1):15337. doi: 10.1038/s41598-023-42224-9.
Methane is a potent greenhouse gas, which has contributed to approximately a fifth of global warming since pre-industrial times. The agricultural sector produces significant methane emissions, especially from livestock, waste management and rice cultivation. Rice fields alone generate around 9% of total anthropogenic emissions. Methane is produced in waterlogged paddy fields by methanogenic archaea, and transported to the atmosphere through the aerenchyma tissue of rice plants. Thus, bioengineering rice with catalysts to detoxify methane en route could contribute to an efficient emission mitigation strategy. Particulate methane monooxygenase (pMMO) is the predominant methane catalyst found in nature, and is an enzyme complex expressed by methanotrophic bacteria. Recombinant expression of pMMO has been challenging, potentially due to its membrane localization, multimeric structure, and polycistronic operon. Here we show the first steps towards the engineering of plants for methane detoxification with the three pMMO subunits expressed in the model systems tobacco and Arabidopsis. Membrane topology and protein-protein interactions were consistent with correct folding and assembly of the pMMO subunits on the plant ER. Moreover, a synthetic self-cleaving polypeptide resulted in simultaneous expression of all three subunits, although low expression levels precluded more detailed structural investigation. The work presents plant cells as a novel heterologous system for pMMO allowing for protein expression and modification.
甲烷是一种强效温室气体，自工业化前时代以来，其导致了约全球升温的五分之一。农业部门产生了大量的甲烷排放，特别是来自牲畜、废物管理和水稻种植。仅水稻田就产生了约 9%的人为甲烷排放总量。在水田的淹水环境中，产甲烷古菌产生甲烷，然后通过水稻植株的通气组织输送到大气中。因此，用催化剂对水稻进行生物工程改造以去除途中的甲烷，可以作为一种有效的减排策略。颗粒态甲烷单加氧酶（pMMO）是自然界中主要的甲烷催化剂，是一种由甲烷营养菌表达的酶复合物。由于其膜定位、多聚体结构和多顺反子操纵子，重组表达 pMMO 具有挑战性。在这里，我们展示了用三种 pMMO 亚基在烟草和拟南芥模型系统中进行植物甲烷解毒工程的初步步骤。膜拓扑结构和蛋白质-蛋白质相互作用与 pMMO 亚基在植物内质网上的正确折叠和组装一致。此外，一种合成的自我切割多肽导致了所有三个亚基的同时表达，尽管低表达水平排除了更详细的结构研究。这项工作将植物细胞作为一种新的 pMMO 异源系统，可以进行蛋白质表达和修饰。
