College of Environmental, Zhejiang University of Technology, Hangzhou, 310032, PR China.
College of Biological and Environmental Engineering, Zhejiang Shuren University, Hangzhou, 310021, PR China.
Chemosphere. 2020 Aug;253:126739. doi: 10.1016/j.chemosphere.2020.126739. Epub 2020 Apr 12.
Biological denitrification is a promising and green technology for air pollution control. To investigate the nitric oxide reductase (NOR) that dominates NO reduction efficiency in biological purification, the heterologous prokaryotic expression system of the norB gene, which encodes the core peptide of the catalytic reduction structure in the NOR from Achromobacter denitrificans strain TB, was constructed in Escherichia coli BL21 (DE3). Results showed that the 1218 bp-long norB gene was expressed at the highest level under 1.0 mM IPTG for 5 h at 30 °C, and the relative expression abundance of norB in recombinant E. coli was increased by 16.6 times compared with that of the wild-type TB. However, the NO reduction efficiency and NOR activity of strain TB was 2.7 and 1.83 times higher than those of recombinant E. coli, respectively. On the basis of genomic reassembly and protein structure modeling, the core peptide of the NOR catalytic reduction structure from Achromobacter sp. TB can independently exert NO reduction. The low NO degradation efficiency of recombinant E. coli may be due to the lack of a NorC-like structure that increases the enzyme activity of the NorB protein. The results of this study can be used as basis for further research on the structure and function of NOR.
生物反硝化是一种有前途的绿色大气污染控制技术。为了研究在生物净化中主导 NO 还原效率的一氧化氮还原酶（NOR），构建了异源原核表达系统，以大肠杆菌 BL21（DE3）表达来自 Achromobacter denitrificans TB 菌株的 NOR 核心肽编码基因 norB。结果表明，在 30°C 下，用 1.0 mM IPTG 诱导 5 小时，可获得最长为 1218 bp 的 norB 基因的最高表达水平，与野生型 TB 相比，重组大肠杆菌中 norB 的相对表达丰度增加了 16.6 倍。然而，TB 菌株的 NO 还原效率和 NOR 活性分别比重组大肠杆菌高 2.7 和 1.83 倍。基于基因组重组装和蛋白质结构建模，Achromobacter sp. TB 的 NOR 催化还原结构的核心肽可独立发挥 NO 还原作用。重组大肠杆菌中 NO 降解效率较低可能是由于缺乏增加 NorB 蛋白酶活性的类似 NorC 的结构。本研究结果可为 NOR 的结构和功能的进一步研究提供依据。
