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Jiang W, Liu Y, Ke Z, Zhang L, Zhang M, Zhou Y, Wang H, Wu C, Qiu J, Hong Q. Substrate preference of carbamate hydrolase CehA reveals its environmental behavior. JOURNAL OF HAZARDOUS MATERIALS 2021; 403:123677. [PMID: 32835992 DOI: 10.1016/j.jhazmat.2020.123677] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/30/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
The cehA gene is the earliest reported and most widely found carbaryl hydrolase gene. CehA detoxifies carbaryl and other carbamate pesticides via de-esterification. Currently, there is no systematic research available on substrate preference or the mechanism of CehA action in different hosts. In this study, we found that CehA from different hosts is highly conserved, with more than 99% amino acid sequence similarity, and that transposable elements exist in both the upstream and downstream regions of cehA. By introducing point mutations into the cehA gene of Sphingobium sp. CFD-1, we obtained and heterologously expressed all reported CehA(CehAS) encoding genes. Assays to determine enzymatic properties and substrate profiles of CehAS showed that each CehA has a significant substrate preference for different carbamate insecticides. Specifically, CehA152Phe/Leu determines the catalytic preference for bicyclic carbamate substrates (carbofuran, carbaryl), while CehA494Thr/Ala and 570Thr/Ile determine the preference for monocyclic carbamate substrates (isoprocarb, propoxur) and linear carbamate substrates (oxamyl, aldicarb), respectively. Considering the existence of transposable elements in the flanking regions of cehA, we speculate that the cehA hosts may have acquired the hydrolysis ability, as well as substrate preference for carbamate pesticides, through horizontal gene transfer and genetic copying errors.
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Affiliation(s)
- Wankui Jiang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Yali Liu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Zhijian Ke
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Lu Zhang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Mingliang Zhang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Yidong Zhou
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Hui Wang
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Chenglong Wu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Jiguo Qiu
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China
| | - Qing Hong
- Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, Nanjing, Jiangsu 210095, PR China.
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Esquirol L, Peat TS, Sugrue E, Balotra S, Rottet S, Warden AC, Wilding M, Hartley CJ, Jackson CJ, Newman J, Scott C. Bacterial catabolism of s-triazine herbicides: biochemistry, evolution and application. Adv Microb Physiol 2020; 76:129-186. [PMID: 32408946 DOI: 10.1016/bs.ampbs.2020.01.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The synthetic s-triazines are abundant, nitrogen-rich, heteroaromatic compounds used in a multitude of applications including, herbicides, plastics and polymers, and explosives. Their presence in the environment has led to the evolution of bacterial catabolic pathways in bacteria that allow use of these anthropogenic chemicals as a nitrogen source that supports growth. Herbicidal s-triazines have been used since the mid-twentieth century and are among the most heavily used herbicides in the world, despite being withdrawn from use in some areas due to concern about their safety and environmental impact. Bacterial catabolism of the herbicidal s-triazines has been studied extensively. Pseudomonas sp. strain ADP, which was isolated more than thirty years after the introduction of the s-triazine herbicides, has been the model system for most of these studies; however, several alternative catabolic pathways have also been identified. Over the last five years, considerable detail about the molecular mode of action of the s-triazine catabolic enzymes has been uncovered through acquisition of their atomic structures. These structural studies have also revealed insights into the evolutionary origins of this newly acquired metabolic capability. In addition, s-triazine-catabolizing bacteria and enzymes have been used in a range of applications, including bioremediation of herbicides and cyanuric acid, introducing metabolic resistance to plants, and as a novel selectable marker in fermentation organisms. In this review, we cover the discovery and characterization of bacterial strains, metabolic pathways and enzymes that catabolize the s-triazines. We also consider the evolution of these new enzymes and pathways and discuss the practical applications that have been considered for these bacteria and enzymes. One Sentence Summary: A detailed understanding of bacterial herbicide catabolic enzymes and pathways offer new evolutionary insights and novel applied tools.
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Affiliation(s)
- Lygie Esquirol
- Biocatalysis & Synthetic Biology Team, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia; Research School of Chemistry, Australian National University, Canberra, ACT, Australia
| | - Thomas S Peat
- CSIRO Biomedical Manufacturing, Parkville, VIC, Australia
| | - Elena Sugrue
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
| | - Sahil Balotra
- Biocatalysis & Synthetic Biology Team, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia
| | - Sarah Rottet
- Biocatalysis & Synthetic Biology Team, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia; Synthetic Biology Future Science Platform, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia
| | - Andrew C Warden
- Biocatalysis & Synthetic Biology Team, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia
| | - Matthew Wilding
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia; CSIRO Biomedical Manufacturing, Parkville, VIC, Australia; Synthetic Biology Future Science Platform, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia
| | - Carol J Hartley
- Biocatalysis & Synthetic Biology Team, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia
| | - Colin J Jackson
- Research School of Chemistry, Australian National University, Canberra, ACT, Australia
| | - Janet Newman
- CSIRO Biomedical Manufacturing, Parkville, VIC, Australia
| | - Colin Scott
- Biocatalysis & Synthetic Biology Team, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia; Synthetic Biology Future Science Platform, CSIRO Land & Water, Black Mountain Science and Innovation Park, Canberra, ACT, Australia
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Ang TF, Maiangwa J, Salleh AB, Normi YM, Leow TC. Dehalogenases: From Improved Performance to Potential Microbial Dehalogenation Applications. Molecules 2018; 23:E1100. [PMID: 29735886 PMCID: PMC6100074 DOI: 10.3390/molecules23051100] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 04/07/2018] [Accepted: 04/09/2018] [Indexed: 11/16/2022] Open
Abstract
The variety of halogenated substances and their derivatives widely used as pesticides, herbicides and other industrial products is of great concern due to the hazardous nature of these compounds owing to their toxicity, and persistent environmental pollution. Therefore, from the viewpoint of environmental technology, the need for environmentally relevant enzymes involved in biodegradation of these pollutants has received a great boost. One result of this great deal of attention has been the identification of environmentally relevant bacteria that produce hydrolytic dehalogenases—key enzymes which are considered cost-effective and eco-friendly in the removal and detoxification of these pollutants. These group of enzymes catalyzing the cleavage of the carbon-halogen bond of organohalogen compounds have potential applications in the chemical industry and bioremediation. The dehalogenases make use of fundamentally different strategies with a common mechanism to cleave carbon-halogen bonds whereby, an active-site carboxylate group attacks the substrate C atom bound to the halogen atom to form an ester intermediate and a halide ion with subsequent hydrolysis of the intermediate. Structurally, these dehalogenases have been characterized and shown to use substitution mechanisms that proceed via a covalent aspartyl intermediate. More so, the widest dehalogenation spectrum of electron acceptors tested with bacterial strains which could dehalogenate recalcitrant organohalides has further proven the versatility of bacterial dehalogenators to be considered when determining the fate of halogenated organics at contaminated sites. In this review, the general features of most widely studied bacterial dehalogenases, their structural properties, basis of the degradation of organohalides and their derivatives and how they have been improved for various applications is discussed.
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Affiliation(s)
- Thiau-Fu Ang
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Jonathan Maiangwa
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Abu Bakar Salleh
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Institute of Bioscience, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Yahaya M Normi
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
| | - Thean Chor Leow
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Enzyme and Microbial Technology Research Centre, Centre of Excellence, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
- Institute of Bioscience, University Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
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Goldsmith M, Tawfik DS. Enzyme engineering: reaching the maximal catalytic efficiency peak. Curr Opin Struct Biol 2017; 47:140-150. [PMID: 29035814 DOI: 10.1016/j.sbi.2017.09.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/04/2017] [Accepted: 09/20/2017] [Indexed: 01/01/2023]
Abstract
The practical need for highly efficient enzymes presents new challenges in enzyme engineering, in particular, the need to improve catalytic turnover (kcat) or efficiency (kcat/KM) by several orders of magnitude. However, optimizing catalysis demands navigation through complex and rugged fitness landscapes, with optimization trajectories often leading to strong diminishing returns and dead-ends. When no further improvements are observed in library screens or selections, it remains unclear whether the maximal catalytic efficiency of the enzyme (the catalytic 'fitness peak') has been reached; or perhaps, an alternative combination of mutations exists that could yield additional improvements. Here, we discuss fundamental aspects of the process of catalytic optimization, and offer practical solutions with respect to overcoming optimization plateaus.
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Affiliation(s)
- Moshe Goldsmith
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel.
| | - Dan S Tawfik
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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Guo Y, Zhao P, Zhang W, Li X, Chen X, Chen D. Catalytic improvement and structural analysis of atrazine chlorohydrolase by site-saturation mutagenesis. Biosci Biotechnol Biochem 2016; 80:1336-43. [DOI: 10.1080/09168451.2016.1156481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Abstract
To improve the catalytic activity of atrazine chlorohydrolase (AtzA), amino acid residues involved in substrate binding (Gln71) and catalytic efficiency (Val12, Ile393, and Leu395) were targeted to generate site-saturation mutagenesis libraries. Seventeen variants were obtained through Haematococcus pluvialis-based screening, and their specific activities were 1.2–5.2-fold higher than that of the wild type. For these variants, Gln71 tended to be substituted by hydrophobic amino acids, Ile393 and Leu395 by polar ones, especially arginine, and Val12 by alanine, respectively. Q71R and Q71M significantly decreased the Km by enlarging the substrate-entry channel and affecting N-ethyl binding. Mutations at sites 393 and 395 significantly increased the kcat/Km, probably by improving the stability of the dual β-sheet domain and the whole enzyme, owing to hydrogen bond formation. In addition, the contradictory relationship between the substrate affinity improvement by Gln71 mutation and the catalytic efficiency improvement by the dual β-sheet domain modification was discussed.
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Affiliation(s)
- Yuan Guo
- College of Life Sciences, Nankai University, Tianjin, China
| | - Panjie Zhao
- College of Life Sciences, Nankai University, Tianjin, China
| | - Wenhao Zhang
- College of Life Sciences, Nankai University, Tianjin, China
| | - Xiaolong Li
- College of Life Sciences, Nankai University, Tianjin, China
| | - Xiwen Chen
- College of Life Sciences, Nankai University, Tianjin, China
| | - Defu Chen
- College of Life Sciences, Nankai University, Tianjin, China
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Zhang L, Chen H, Li Y, Li Y, Wang S, Su J, Liu X, Chen D, Chen X. Evaluation of the agronomic performance of atrazine-tolerant transgenic japonica rice parental lines for utilization in hybrid seed production. PLoS One 2014; 9:e108569. [PMID: 25275554 PMCID: PMC4183513 DOI: 10.1371/journal.pone.0108569] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 09/01/2014] [Indexed: 11/18/2022] Open
Abstract
Currently, the purity of hybrid seed is a crucial limiting factor when developing hybrid japonica rice (Oryza sativa L.). To chemically control hybrid seed purity, we transferred an improved atrazine chlorohydrolase gene (atzA) from Pseudomonas ADP into hybrid japonica parental lines (two maintainers, one restorer), and Nipponbare, by using Agrobacterium-mediated transformation. We subsequently selected several transgenic lines from each genotype by using PCR, RT-PCR, and germination analysis. In the presence of the investigated atrazine concentrations, particularly 150 µM atrazine, almost all of the transgenic lines produced significantly larger seedlings, with similar or higher germination percentages, than did the respective controls. Although the seedlings of transgenic lines were taller and gained more root biomass compared to the respective control plants, their growth was nevertheless inhibited by atrazine treatment compared to that without treatment. When grown in soil containing 2 mg/kg or 5 mg/kg atrazine, the transgenic lines were taller, and had higher total chlorophyll contents than did the respective controls; moreover, three of the strongest transgenic lines completely recovered after 45 days of growth. After treatment with 2 mg/kg or 5 mg/kg of atrazine, the atrazine residue remaining in the soil was 2.9–7.0% or 0.8–8.7% respectively, for transgenic lines, and 44.0–59.2% or 28.1–30.8%, respectively, for control plants. Spraying plants at the vegetative growth stage with 0.15% atrazine effectively killed control plants, but not transgenic lines. Our results indicate that transgenic atzA rice plants show tolerance to atrazine, and may be used as parental lines in future hybrid seed production.
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Affiliation(s)
- Luhua Zhang
- Laboratory of Molecular Genetics, College of Life Sciences, Nankai University, Tianjin, China
| | - Haiwei Chen
- Laboratory of Molecular Genetics, College of Life Sciences, Nankai University, Tianjin, China
| | - Yanlan Li
- Laboratory of Molecular Genetics, College of Life Sciences, Nankai University, Tianjin, China
| | - Yanan Li
- Laboratory of Molecular Genetics, College of Life Sciences, Nankai University, Tianjin, China
| | | | - Jinping Su
- Tianjin Crop Research Institute, Tianjin, China
| | - Xuejun Liu
- Tianjin Crop Research Institute, Tianjin, China
| | - Defu Chen
- Laboratory of Molecular Genetics, College of Life Sciences, Nankai University, Tianjin, China
- * E-mail: (DC); (XC)
| | - Xiwen Chen
- Laboratory of Molecular Genetics, College of Life Sciences, Nankai University, Tianjin, China
- * E-mail: (DC); (XC)
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