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Citation
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HERO ID
4132425
Reference Type
Journal Article
Title
Iron-Dependent Enzyme Catalyzes the Initial Step in Biodegradation of N-Nitroglycine by Variovorax sp. Strain JS1663
Author(s)
Mahan, KM; Zheng, H; Fida, TT; Parry, RJ; Graham, DE; Spain, JC
Year
2017
Is Peer Reviewed?
Yes
Journal
Applied and Environmental Microbiology
ISSN:
0099-2240
EISSN:
1098-5336
Volume
83
Issue
15
Language
English
PMID
28526789
DOI
10.1128/AEM.00457-17
Web of Science Id
WOS:000406655100004
URL
http://
://WOS:000406655100004
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Abstract
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. 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. This is the first instance of a PAS domain present in a denitration enzyme. The 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.IMPORTANCE The production of antibiotics and other allelopathic chemicals is a major aspect of chemical ecology. The biodegradation of such chemicals can play an important ecological role in mitigating or eliminating the effects of such compounds. N-Nitroglycine (NNG) is produced by the Gram-positive filamentous soil bacterium Streptomyces noursei This study reports the isolation of a Gram-negative soil bacterium, Variovorax sp. strain JS1663, that is able to use NNG as a sole growth substrate. The proposed degradation pathway occurs via a β-elimination reaction that releases nitrite from NNG. The novel NNG lyase requires iron(II) for activity. The identification of a novel enzyme and catabolic pathway provides evidence of a substantial and underappreciated flux of the antibiotic in natural ecosystems. Understanding the NNG biodegradation pathway will help identify other enzymes that cleave the N-N bond and facilitate the development of enzymes to cleave similar bonds in synthetic nitramine explosives.
Tags
IRIS
•
Nitrate/Nitrite
Broad LitSearch 2016/1/1 - 2017/12/5
Refs found by LitSearch but not ATSDR/IARC
PubMed
WoS
Refs found only by 2017 LitSearch or Citation Mapping
Ref Types 12/2017
All Others
LitSearch Update 2016-2017
PubMed
WoS
•
RDX (121-82-4)
Database Searches November 2017
Pubmed 11/17
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