Heterologous expression and functional study of nitric oxide reductase catalytic reduction peptide from Achromobacter denitrificans strain TB.

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.