Biochemical characteristics of a nitroreductase with diverse substrate specificity from Streptomyces mirabilis DUT001. (2nd October 2018)

• Record Type: Journal Article
• Authors: Yang, Jun; Bai, Jing; Qu, Mingbo; Xie, Bo; Yang, Qing
• Is Part Of: Biotechnology and applied biochemistry. Volume 66:Number 1(2019)
• Page Start: 33
• Page End: 42
• Publication Date: 2018-10-02
• Subjects: biotransformation -- diverse substrate specificity -- flavin mononucleotide reduction -- nitro compounds, nitroreductase -- Streptomyces; Biotechnology -- Periodicals; Biochemical engineering -- Periodicals; Biochemistry -- Periodicals; Biochemistry -- Periodicals; Genetic Techniques -- Periodicals; Microbiological Techniques -- Periodicals; 660.6
• DOI: 10.1002/bab.1692
• Languages: English
• ISSNs: 0885-4513

Abstract

Abstract: A nitroreductase‐encoded gene from an efficient nitro‐reducing bacterium Streptomyces mirabilis DUT001, named snr, was cloned and heterogeneously expressed in Escherichia coli . The purified Streptomyces nitroreductase SNR was a homodimer with an apparent subunit molecular weight of 24 kDa and preferred NADH to NADPH as a cofactor. By enzyme incubation and isothermal calorimetry experiments, flavin mononucleotide (FMN) was found to be the preferred flavin cofactor; the binding process was exothermic and primarily enthalpy driven. The enzyme can reduce multiple nitro compounds and flavins, including antibacterial drug nitrofurazone, priority pollutants 2, 4‐dinitrotoluene and 2, 4, 6‐trinitrotoluene, as well as key chemical intermediates 3‐nitrophthalimide, 4‐nitrophthalimide, and 4‐nitro‐1, 8‐naphthalic anhydride. Among the substrates tested, the highest activity of k cat(app) / K m(app) (0.234 μM −1 Sec −1 ) was observed for the reduction of FMN. Multiple sequence alignment revealed that the high FMN reduction activity of SNR may be due to the absence of a helix, constituting the entrance to the substrate pocket in other nitroreductases.