Nitroreductase from Salmonella typhimurium: characterization and catalytic activity

Abstract

The biocatalytic activity of nitroreductase from Salmonella typhimurium (NRSal) was investigated for the reduction of alpha,beta-unsaturated carbonyl compounds, nitroalkenes, and nitroaromatics. The synthesized gene was subcloned into a pET28 overexpression system in E.coli BL21 strain, and the corresponding expressed protein was purified to homogeneity with 15% protein mass yield and 41% of total activity recovery. NRSal showed broad substrate acceptance for various nitro compounds such as 1-nitrocyclohexene and aliphatic nitroalkenes (alkene reductase activity), as well as nitrobenzene (nitroreductase activity), with substrate conversion efficiency of > 95%. However, the reduction of enones was generally low, proceeding albeit with high stereoselectivity. The efficient biocatalytic reduction of substituted nitroalkenes provides a route for the preparation of the corresponding nitroalkanes. NRSal also demonstrated the first single isolated enzyme-catalyzed reduction of nitrobenzene to aniline through the formation of nitrosobenzene and phenylhydroxylamine as intermediates. However, chemical condensation of the two intermediates to produce azoxybenzene currently limits the yield of aniline.

Microbial community structure and function of Nitrobenzene reduction biocathode in response to carbon source switchover

“…9B) among 6 classes of Actinobacteria, Cyanobacteria (phylum), Clostridia, Planctomycetacia, b-proteobacteria, d-proteobacteria and g-proteobacteria. The OYE-like FMN was the first flavin-dependent enzyme that displayed nitroreductase activity (Yanto et al, 2010). Each monomer of OYE contains FMN as a non-covalently bound cofactor and uses NADPH as electrons donor.…”

Understanding the Broad Substrate Repertoire of Nitroreductase Based on Its Kinetic Mechanism

“…In particular, the NR of Mycobacterium smegmatis (NR-Ms) converts the nitro group of benzothiazinone to an amine (20). The NR from Salmonella typhimurium (NR-Sal) displays both nitroreductase and enoate reductase activity, transforming nitrobenzene to nitrosobenzene, phenylhydroxylamine, and even the fully reduced product aniline (13). Similarly, the first NR of Klebsiella sp.…”

“…The broad substrate repertoire of nitroreductase makes it an attractive enzyme for bioremediation of nitroaromatics and for producing valuable pharmacological reagents because this one enzyme could be used to transform a variety of related compounds (6,13). A number of enzymes are known that transform diverse substrates, including certain cytochrome P450s (22,23), and pentaerythritol tetranitrate reductase (24,25).…”

“…Aromatic amines would be valuable synthons, and there are a few instances in which amine products have been detected (12,13,20,21). In particular, the NR of Mycobacterium smegmatis (NR-Ms) converts the nitro group of benzothiazinone to an amine (20).…”

Quinone- and nitroreductase reactions of Thermotoga maritima peroxiredoxin–nitroreductase hybrid enzyme

“…reductase [4], and Salmonella typhimurium nitroreductase [5], or 52 with E. coli NAD(P)H-dependent minor nitroreductase-B [6], e.g.,…”