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Updated: Jun 2, 2026
13:31
Generation of Enterobacter sp. YSU Auxotrophs Using Transposon Mutagenesis
Published on: October 31, 2014
Retro-nitroreductase, a putative evolutionary precursor to Enterobacter cloacae strain 96-3 nitroreductase
R L Koder1, O Oyedele, A F Miller
1Department of Chemistry, The University of Kentucky, Lexington 40506-0055, USA.
Antioxidants & Redox Signaling
|January 5, 2002
Summary
Enterobacter cloacae nitroreductase (NR) was thought to be highly efficient due to its environment. However, a newly characterized enzyme, retro-nitroreductase, shows similar activity, suggesting high efficiency is a general trait of these bacterial nitroreductases.
Area of Science:
- Biochemistry
- Enzymology
- Microbiology
Background:
- Enterobacter cloacae strain 96-3 nitroreductase (NR) is a flavoenzyme that reduces nitroaromatic compounds.
- NR was believed to have evolved enhanced efficiency due to environmental exposure to nitroaromatics.
- Previous studies suggested NR's high catalytic efficiency stemmed from its isolation source.
Purpose of the Study:
- To investigate if environmental factors significantly enhance nitroreductase efficiency.
- To clone and biochemically characterize a nitroreductase from a clinical isolate of Enterobacter cloacae.
- To compare the catalytic efficiency of NR with a homologous enzyme from a strain not exposed to high nitroaromatic concentrations.
Main Methods:
- Cloning of a nitroreductase gene from a clinical Enterobacter cloacae isolate.
- Biochemical characterization of the newly identified nitroreductase (retro-nitroreductase).
- Comparative analysis of enzyme kinetics, including NADH oxidation and dinitrobenzyl alcohol reduction.
Main Results:
- A novel nitroreductase, retro-nitroreductase, was identified with 96.7% sequence identity to NR.
- Retro-nitroreductase exhibited a twofold lower catalytic efficiency for NADH oxidation compared to NR.
- The reduction of dinitrobenzyl alcohol showed no significant difference in efficiency between NR and retro-nitroreductase.
Conclusions:
- The high catalytic activity of Enterobacter cloacae nitroreductase (NR) is likely a general characteristic of the enzyme family, not solely due to environmental adaptation.
- Environmental factors may not be the primary driver for the enhanced nitroreduction efficiency observed in NR.
- Further research into the general properties of Enterobacter cloacae nitroreductases is warranted.
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