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Cotinine Hydroxylase CotA Initiates Biodegradation of Wastewater Micropollutant Cotinine in Nocardioides sp. Strain JQ2195
- Source :
- Applied and Environmental Microbiology. 87
- Publication Year :
- 2021
- Publisher :
- American Society for Microbiology, 2021.
-
Abstract
- Cotinine is a stable toxic contaminant, produced as a by-product of smoking. It is of emerging concern due to its global distribution in aquatic environments. Microorganisms have the potential to degrade cotinine; however, the genetic mechanisms of this process are unknown. Nocardioides sp. strain JQ2195 is a pure-culture strain that has been reported to degrade cotinine at micropollutant concentrations. This strain utilizes cotinine as its sole carbon and nitrogen source. In this study, a 50-kb gene cluster (designated cot), involved in cotinine degradation, was predicted based on genomic and transcriptomic analyses. A novel three-component cotinine hydroxylase gene (designated cotA1A2A3), which initiated cotinine catabolism, was identified and characterized. CotA from Shinella sp. strain HZN7 was heterologously expressed and purified and was shown to convert cotinine into 6-hydroxycotinine. H218O-labeling and electrospray ionization-mass spectrometry (ESI-MS) analysis confirmed that the hydroxyl group incorporated into 6-hydroxycotinine was derived from water. This study provides new molecular insights into the microbial metabolism of heterocyclic chemical pollutants. IMPORTANCE In the human body, cotinine is the major metabolite of nicotine, and 10 to 15% of generated cotinine is excreted in urine. Cotinine is a structural analogue of nicotine and is much more stable than nicotine. Increased tobacco consumption has led to high environmental concentrations of cotinine, which may have detrimental effects on aquatic ecosystems and human health. Nocardioides sp. strain JQ2195 is a unique cotinine-degrading bacterium. However, the underlying genetic and biochemical foundations of cotinine degradation are still unknown. In this study, a 50-kb gene cluster (designated cot) was identified by genomic and transcriptomic analyses as being involved in the degradation of cotinine. A novel three-component cotinine hydroxylase gene (designated cotA1A2A3) catalyzed cotinine to 6-hydroxy-cotinine. This study provides new molecular insights into the microbial degradation and enzymatic transformation of cotinine.
- Subjects :
- 0301 basic medicine
Ecology
biology
Catabolism
Metabolite
Microbial metabolism
010501 environmental sciences
biology.organism_classification
01 natural sciences
Applied Microbiology and Biotechnology
Nicotine
03 medical and health sciences
chemistry.chemical_compound
030104 developmental biology
Biochemistry
chemistry
Gene cluster
medicine
Microbial biodegradation
Cotinine
Bacteria
0105 earth and related environmental sciences
Food Science
Biotechnology
medicine.drug
Subjects
Details
- ISSN :
- 10985336 and 00992240
- Volume :
- 87
- Database :
- OpenAIRE
- Journal :
- Applied and Environmental Microbiology
- Accession number :
- edsair.doi...........71aa54130b70c7af13d1bdb321ca3a3e