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Title: Iron-Dependent Enzyme Catalyzes the Initial Step in Biodegradation of N -Nitroglycine by Variovorax sp. Strain JS1663

Nitramines are key constituents of most of the explosives currently in use and consequently contaminate soil and groundwater at many military facilities around the world. Toxicity from nitramine contamination poses a health risk to plants and animals. Thus, understanding how nitramines are biodegraded is critical to environmental remediation. The biodegradation of synthetic nitramine compounds such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) has been studied for decades, but little is known about the catabolism of naturally produced nitramine compounds. Here in this study, we report the isolation of a soil bacterium, Variovorax sp. strain JS1663, that degrades N-nitroglycine (NNG), a naturally produced nitramine, and the key enzyme involved in its catabolism. Variovorax sp. JS1663 is a Gram-negative, non-spore-forming motile bacterium isolated from activated sludge based on its ability to use NNG as a sole growth substrate under aerobic conditions. A single gene (nnlA) encodes an iron-dependent enzyme that releases nitrite from NNG through a proposed β-elimination reaction. Bioinformatics analysis of the amino acid sequence of NNG lyase identified a PAS (Per-Arnt-Sim) domain. PAS domains can be associated with heme cofactors and function as signal sensors in signaling proteins. Finally, this is the first instance of a PAS domain present in a denitration enzyme. Themore » NNG biodegradation pathway should provide the basis for the identification of other enzymes that cleave the N—N bond and facilitate the development of enzymes to cleave similar bonds in RDX, nitroguanidine, and other nitramine explosives.« less
Authors:
ORCiD logo [1] ;  [2] ;  [2] ;  [3] ; ORCiD logo [1] ;  [4]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
  2. Georgia Inst. of Technology, Atlanta, GA (United States). Environmental Engineering Program
  3. Rice Univ., Houston, TX (United States). Dept. of Chemistry and Biochemistry and Cell Biology
  4. Georgia Inst. of Technology, Atlanta, GA (United States). Environmental Engineering Program; Univ. of West Florida, Pensacola, FL (United States). Center for Environmental Diagnostics and Bioremediation
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Applied and Environmental Microbiology
Additional Journal Information:
Journal Volume: 83; Journal Issue: 15; Journal ID: ISSN 0099-2240
Publisher:
American Society for Microbiology
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; N-nitroglycine; Streptomyces noursei; Variovorax sp. strain JS1663; naturally occurring nitro compound; nitramine degradation
OSTI Identifier:
1408014