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Wang X, Kong D, Huang T, Xu F, Tang MC, Deng Z, Lin S. Flavoprotein StnP2 Catalyzes the β-Carboline Formation during the Streptonigrin Biosynthesis. ACS Chem Biol 2022; 17:3499-3506. [PMID: 36409520 DOI: 10.1021/acschembio.2c00704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
β-Carboline (βC) alkaloids constitute a large family of indole alkaloids that exhibit diverse pharmacological properties, such as antitumor, antiviral, antiparasitic, and antimicrobial activities. Here, we report that a flavoprotein StnP2 catalyzes the dehydrogenation at C1-N2 of a tetrahydro-β-carboline (THβC) generating a 3,4-dihydro-β-carboline (DHβC), and the DHβC subsequently undergoes a spontaneous dehydrogenation to βC formation involved in the biosynthesis of the antitumor agent streptonigrin. Biochemical characterization showed that StnP2 catalyzed the highly regio- and stereo-selective dehydrogenation, and StnP2 exhibits promiscuity toward different THβCs. This study provides an alternative kind of enzyme catalyzing the biosynthesis of βC alkaloids and enhances the importance of flavoproteins.
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Affiliation(s)
- Xiaozheng Wang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Dekun Kong
- Biotechnology Research Center, Southwest University, No. 2 Tiansheng Road, Chongqing 400715, China
| | - Tingting Huang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Fei Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Man-Cheng Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Zixin Deng
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Shuangjun Lin
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.,Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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2
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Yu C, Wang H, Blaustein RA, Guo L, Ye Q, Fu Y, Fan J, Su X, Hartmann EM, Shen C. Pangenomic and functional investigations for dormancy and biodegradation features of an organic pollutant-degrading bacterium Rhodococcus biphenylivorans TG9. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 809:151141. [PMID: 34688761 DOI: 10.1016/j.scitotenv.2021.151141] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 10/14/2021] [Accepted: 10/18/2021] [Indexed: 06/13/2023]
Abstract
Environmental bacteria contain a wealth of untapped potential in the form of biodegradative genes. Leveraging this potential can often be confounded by a lack of understanding of fundamental survival strategies, like dormancy, for environmental stress. Investigating bacterial dormancy-to-degradation relationships enables improvement of bioremediation. Here, we couple genomic and functional assessment to provide context for key attributes of the organic pollutant-degrading strain Rhodococcus biphenylivorans TG9. Whole genome sequencing, pangenome analysis and functional characterization were performed to elucidate important genes and gene products, including antimicrobial resistance, dormancy, and degradation. Rhodococcus as a genus has strong potential for degradation and dormancy, which we demonstrate using R. biphenylivorans TG9 as a model. We identified four Resuscitation-promoting factor (Rpf) encoding genes in TG9 involved in dormancy and resuscitation. We demonstrate that R. biphenylivorans TG9 grows on fourteen typical organic pollutants, and exhibits a robust ability to degrade biphenyl and several congeners of polychlorinated biphenyls. We further induced TG9 into a dormant state and demonstrated pronounced differences in morphology and activity. Together, these results expand our understanding of the genus Rhodococcus and the relationship between dormancy and biodegradation in the presence of environmental stressors.
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Affiliation(s)
- Chungui Yu
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hui Wang
- College of Eco-Environmental Engineering, Guizhou Minzu University, Guiyang, Guizhou, China; Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Ryan Andrew Blaustein
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, USA
| | - Li Guo
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Qi Ye
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yulong Fu
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jiahui Fan
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Xiaomei Su
- College of Geography and Environmental Science, Zhejiang Normal University, Jinhua, Zhejiang, China; Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Erica Marie Hartmann
- Department of Civil and Environmental Engineering, Northwestern University, Evanston, IL, USA.
| | - Chaofeng Shen
- Department of Environmental Engineering, College of Environmental and Resource Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
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Dutta K, Shityakov S, Khalifa I. New Trends in Bioremediation Technologies Toward Environment-Friendly Society: A Mini-Review. Front Bioeng Biotechnol 2021; 9:666858. [PMID: 34409018 PMCID: PMC8365754 DOI: 10.3389/fbioe.2021.666858] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 05/26/2021] [Indexed: 01/29/2023] Open
Abstract
Today's environmental balance has been compromised by the unreasonable and sometimes dangerous actions committed by humans to maintain their dominance over the Earth's natural resources. As a result, oceans are contaminated by the different types of plastic trash, crude oil coming from mismanagement of transporting ships spilling it in the water, and air pollution due to increasing production of greenhouse gases, such as CO2 and CH4 etc., into the atmosphere. The lands, agricultural fields, and groundwater are also contaminated by the infamous chemicals viz., polycyclic aromatic hydrocarbons, pyrethroids pesticides, bisphenol-A, and dioxanes. Therefore, bioremediation might function as a convenient alternative to restore a clean environment. However, at present, the majority of bioremediation reports are limited to the natural capabilities of microbial enzymes. Synthetic biology with uncompromised supervision of ethical standards could help to outsmart nature's engineering, such as the CETCH cycle for improved CO2 fixation. Additionally, a blend of synthetic biology with machine learning algorithms could expand the possibilities of bioengineering. This review summarized current state-of-the-art knowledge of the data-assisted enzyme redesigning to actively promote new research on important enzymes to ameliorate the environment.
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Affiliation(s)
- Kunal Dutta
- Department of Human Physiology, Vidyasagar University, Medinipur, India
| | - Sergey Shityakov
- Department of Chemoinformatics, Infochemistry Scientific Center, Saint Petersburg National Research University of Information Technologies, Mechanics and Optics (ITMO University), Saint-Petersburg, Russia
| | - Ibrahim Khalifa
- Food Technology Department, Faculty of Agriculture, Benha University, Moshtohor, Egypt
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pahE, a Functional Marker Gene for Polycyclic Aromatic Hydrocarbon-Degrading Bacteria. Appl Environ Microbiol 2019; 85:AEM.02399-18. [PMID: 30478232 DOI: 10.1128/aem.02399-18] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 11/09/2018] [Indexed: 11/20/2022] Open
Abstract
The characterization of native polycyclic aromatic hydrocarbon (PAH)-degrading bacteria is significant for understanding the PAH degradation process in the natural environment and developing effective remediation technologies. Most previous investigations of PAH-degrading bacteria in environmental samples employ pahAc, which encodes the α-subunit of PAH ring-hydroxylating dioxygenase, as a functional marker gene. However, the poor phylogenetic resolution and nonspecificity of pahAc result in a misestimation of PAH-degrading bacteria. Here, we propose a PAH hydratase-aldolase-encoding gene, pahE, as a superior biomarker for PAH-degrading bacteria. Comparative phylogenetic analysis of the key enzymes involved in the upper pathway of PAH degradation indicated that pahE evolved dependently from a common ancestor. A phylogenetic tree constructed based on PahE is largely congruent with PahAc-based phylogenies, except for the dispersion of several clades of other non-PAH-degrading aromatic hydrocarbon dioxygenases present in the PahAc tree. Analysis of pure strains by PCR confirmed that pahE can specifically distinguish PAH-degrading bacteria, while pahAc cannot. Illumina sequencing of pahE and pahAc amplicons showed more genotypes and higher specificity and resolution for pahE Novel reads were also discovered among the pahE amplicons, suggesting the presence of novel PAH-degrading populations. These results suggest that pahE is a more powerful biomarker for exploring the ecological role and degradation potential of PAH-degrading bacteria in ecosystems, which is significant to the bioremediation of PAH pollution and environmental microbial ecology.IMPORTANCE PAH contamination has become a worldwide environmental issue because of the potential toxic effects on natural ecosystems and human health. Biotransformation and biodegradation are considered the main natural elimination forms of PAHs from contaminated sites. Therefore, the knowledge of the degradation potential of the microbial community in contaminated sites is crucial for PAH pollution bioremediation. However, the nonspecificity of pahAc as a functional marker of PAH-degrading bacteria has resulted neither in a reliable prediction of PAH degradation potential nor an accurate assessment of degradation. Here, we introduced pahE encoding the PAH hydratase-aldolase as a new and better functional marker gene of PAH-degrading bacteria. This study provides a powerful molecular tool to more effectively explore the ecological role and degradation potential of PAH-degrading bacteria in ecosystems, which is significant to the bioremediation of PAH pollution.
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Verma N, Kantiwal U, Nitika, Yadav YK, Teli S, Goyal D, Pandey J. Catalytic Promiscuity of Aromatic Ring-Hydroxylating Dioxygenases and Their Role in the Plasticity of Xenobiotic Compound Degradation. MICROORGANISMS FOR SUSTAINABILITY 2019. [DOI: 10.1007/978-981-13-7462-3_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Li T, Li S, Liang C, Zhu J, Liu M, Yang Y. Chemical shift assignments of RHE_RS02845, a NTF2-like domain-containing protein from Rhizobium etli. BIOMOLECULAR NMR ASSIGNMENTS 2018; 12:249-252. [PMID: 29572784 DOI: 10.1007/s12104-018-9817-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 03/20/2018] [Indexed: 06/08/2023]
Abstract
The nuclear transport factor 2 (NTF2) like superfamily includes members of the NTF2 family, delta-5-3-ketosteroid isomerases, and the beta subunit of ring hydroxygenases. This family plays important roles in both eukaryotic and prokaryotic cells, and is taken as a classic example of divergent evolution because proteins in this family exhibit diverse biological functions, although share common structural features. We cloned the gene RHE_RS02845 encoding a predicted NTF2-like domain-containing protein in Rhizobium etli, and prepared U-13C/15N-labeled protein samples for its three-dimensional NMR structural determination. Here, chemical shift assignments for both backbone and side-chain atoms are reported, which is prerequisite for further structural calculation and functional research using NMR spectroscopy.
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Affiliation(s)
- Tao Li
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shuangli Li
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chunjie Liang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jiang Zhu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Yunhuang Yang
- State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Center for Magnetic Resonance, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, 430071, China.
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Yavas A, Icgen B. Diversity of the Aromatic-Ring-Hydroxylating Dioxygenases in the Monoaromatic Hydrocarbon Degraders Held by a Common Ancestor. BULLETIN OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2018; 101:410-416. [PMID: 29752518 DOI: 10.1007/s00128-018-2350-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/02/2018] [Indexed: 05/02/2023]
Abstract
Aromatic ring hydroxylating dioxygenases (ARHDs), harboured by a variety of bacteria, catalyze the initial reaction in the degradation of a wide range of toxic environmental contaminants like aromatic and polycyclic aromatic hydrocarbons (PAHs). Regardless of the source, bacteria harbouring RHDs play major role in the removal of these toxic contaminants. The diversity of ARHDs in contaminated sites is supposed to be huge. However, most of the ARHD diversity studies are based on the PAH degraders and the ARHD diversity in the monoaromatic hydrocarbon degraders has not fully explored yet. In this study, therefore, the ARHD gene from nine different genara of the monoaromatic hydrocarbon degraders including Raoultella, Stenotrophomons, Staphylococcus, Acinetobacter, Pseudomonas, Serratia, Comamonas, Pantoea, and Micrococcus was analysed through polymerase chain reactions and sequencing. The sequence alignments of the ARHD amplicons with 81%-99% homologies were found to be highly related and held by divergent evolution from a common ancestor.
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Affiliation(s)
- Alper Yavas
- Department of Biotechnology, Middle East Technical University, 06800, Ankara, Turkey
| | - Bulent Icgen
- Department of Biotechnology, Middle East Technical University, 06800, Ankara, Turkey.
- Department of Environmental Engineering, Middle East Technical University, 06800, Ankara, Turkey.
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Khara P, Roy M, Chakraborty J, Dutta A, Dutta TK. Characterization of a topologically unique oxygenase from Sphingobium sp. PNB capable of catalyzing a broad spectrum of aromatics. Enzyme Microb Technol 2018; 111:74-80. [DOI: 10.1016/j.enzmictec.2017.10.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 08/25/2017] [Accepted: 10/16/2017] [Indexed: 11/25/2022]
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10
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Fu B, Xu T, Cui Z, Ng HL, Wang K, Li J, Li QX. Mutation of Phenylalanine-223 to Leucine Enhances Transformation of Benzo[a]pyrene by Ring-Hydroxylating Dioxygenase of Sphingobium sp. FB3 by increasing Accessibility of the Catalytic Site. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:1206-1213. [PMID: 29336152 DOI: 10.1021/acs.jafc.7b05018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Burning of agricultural biomass generates polycyclic aromatic hydrocarbons (PAHs) including the carcinogen benzo[a]pyrene, of which the catabolism is primarily initiated by a ring-hydroxylating dioxygenase (RHD). This study explores catalytic site accessibility and its role in preferential catabolism of some PAHs over others. The genes flnA1f, flnA2f, flnA3, and flnA4, encoding the oxygenase α and β subunits, ferredoxin, and ferredoxin reductase, respectively, of the RHD enzyme complex (FlnA) were cloned from Sphingobium sp. FB3 and coexpressed in E. coli BL21. The FlnA effectively transformed fluoranthene but not benzo[a]pyrene. Substitution of the bulky phenylalanine-223 by leucine reduces the steric constraint in the substrate entrance to make the catalytic site of FlnA more accessible to large substrates, as visualized by 3D modeling, and allows the FlnA mutant to efficiently transform benzo[a]pyrene. Accessibility of the catalytic site to PAHs is a mechanism of RHD substrate specificity. The results shed light on why some PAHs are more recalcitrant than others.
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Affiliation(s)
- Bo Fu
- Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University , 2 Yuanmingyuan West Road, Beijing 100193, China
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
| | - Ting Xu
- Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University , 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Zhongli Cui
- Department of Microbiology, College of Life Sciences, Key Laboratory for Microbiological Engineering of Agricultural Environment of Ministry of Agriculture, Nanjing Agricultural University , Nanjing, Jiangsu 201195, China
| | - Ho Leung Ng
- Department of Biochemistry & Molecular Biophysics, Kansas State University , Manhattan, Kansas 66506, United States
| | - Kai Wang
- Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University , 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Ji Li
- Beijing Key Laboratory of Biodiversity and Organic Farming, College of Resources and Environmental Sciences, China Agricultural University , 2 Yuanmingyuan West Road, Beijing 100193, China
| | - Qing X Li
- Department of Molecular Biosciences and Bioengineering, University of Hawaii at Manoa , Honolulu, Hawaii 96822, United States
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Varjani SJ, Joshi RR, Senthil Kumar P, Srivastava VK, Kumar V, Banerjee C, Praveen Kumar R. Polycyclic Aromatic Hydrocarbons from Petroleum Oil Industry Activities: Effect on Human Health and Their Biodegradation. ENERGY, ENVIRONMENT, AND SUSTAINABILITY 2018. [DOI: 10.1007/978-981-10-7413-4_9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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12
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Hawrot-Paw M, Koniuszy A, Mikiciuk M, Izwikow M, Stawicki T, Sędłak P. Analysis of ecotoxic influence of waste from the biomass gasification process. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2017; 24:15022-15030. [PMID: 28493186 PMCID: PMC5486619 DOI: 10.1007/s11356-017-9011-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 04/10/2017] [Indexed: 06/07/2023]
Abstract
The purpose of this research was evaluation of the effect of soil contamination with waste coming from biomass gasification on chosen indicators of its biological activity, growth and development of spring barley, and change of physiological parameters of the plant. Chromatographic content and basic rheological parameters of the substances under research were also analyzed. Liquid wastes, tar, and mixture of tar and engine oil were introduced to the soil in the amount of 100 mg kg-1 DM soil. Based on the conducted research, it was ascertained that the changes in the number and activity of soil microorganisms were determined by the type of waste and its dose. Individual groups of microorganisms showed different sensitivity to the presence of pollution; however, the impact of tar and engine oil mixture was generally more disadvantageous. Presence of contaminants in the soil limited the growth of roots and aboveground parts of spring barley, especially when the dose was 10,000 mg kg-1 DM soil. The unfavorable impact of waste on photosynthesis efficiency on assimilation pigment synthesis and water content in the plant was recorded.
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Affiliation(s)
- Małgorzata Hawrot-Paw
- Department of Agrotechnical Systems Engineering, West Pomeranian University of Technology, Papieża Pawła VI 1, 71-459, Szczecin, Poland.
| | - Adam Koniuszy
- Department of Agrotechnical Systems Engineering, West Pomeranian University of Technology, Papieża Pawła VI 1, 71-459, Szczecin, Poland
| | - Małgorzata Mikiciuk
- Department of Plant Physiology and Biochemistry, West Pomeranian University of Technology, Słowackiego 17, 71-434, Szczecin, Poland
| | - Monika Izwikow
- Department of Agrotechnical Systems Engineering, West Pomeranian University of Technology, Papieża Pawła VI 1, 71-459, Szczecin, Poland
| | - Tomasz Stawicki
- Department of Agrotechnical Systems Engineering, West Pomeranian University of Technology, Papieża Pawła VI 1, 71-459, Szczecin, Poland
| | - Paweł Sędłak
- Department of Agrotechnical Systems Engineering, West Pomeranian University of Technology, Papieża Pawła VI 1, 71-459, Szczecin, Poland
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Recovery and Utilization of Lignin Monomers as Part of the Biorefinery Approach. ENERGIES 2016. [DOI: 10.3390/en9100808] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Lan Y, Zou Y, Huang T, Wang X, Brock NL, Deng Z, Lin S. Indole methylation protects diketopiperazine configuration in the maremycin biosynthetic pathway. Sci China Chem 2016. [DOI: 10.1007/s11426-016-0026-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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George KW, Hay AG. Bacterial strategies for growth on aromatic compounds. ADVANCES IN APPLIED MICROBIOLOGY 2016; 74:1-33. [PMID: 21459192 DOI: 10.1016/b978-0-12-387022-3.00005-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Although the biodegradation of aromatic compounds has been studied for over 40 years, there is still much to learn about the strategies bacteria employ for growth on novel substrates. Elucidation of these strategies is crucial for predicting the environmental fate of aromatic pollutants and will provide a framework for the development of engineered bacteria and degradation pathways. In this chapter, we provide an overview of studies that have advanced our knowledge of bacterial adaptation to aromatic compounds. We have divided these strategies into three broad categories: (1) recruitment of catabolic genes, (2) expression of "repair" or detoxification proteins, and (3) direct alteration of enzymatic properties. Specific examples from the literature are discussed, with an eye toward the molecular mechanisms that underlie each strategy.
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Affiliation(s)
- Kevin W George
- Field of Environmental Toxicology, Cornell University Ithaca, New York, USA; Department of Microbiology, Wing Hall, Cornell University Ithaca, New York, USA
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16
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Biochemical Characterization of Inducible ‘Reductase’ Component of Benzoate Dioxygenase and Phthalate Isomer Dioxygenases from Pseudomonas aeruginosa strain PP4. Appl Biochem Biotechnol 2015. [DOI: 10.1007/s12010-015-1744-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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17
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Identification of a gene cluster associated with triclosan catabolism. Biodegradation 2015; 26:235-46. [DOI: 10.1007/s10532-015-9730-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Accepted: 04/16/2015] [Indexed: 11/26/2022]
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18
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Liao RZ, Siegbahn PEM. Mechanism and selectivity of the dinuclear iron benzoyl-coenzyme A epoxidase BoxB. Chem Sci 2015; 6:2754-2764. [PMID: 28706665 PMCID: PMC5489048 DOI: 10.1039/c5sc00313j] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/02/2015] [Indexed: 12/22/2022] Open
Abstract
DFT calculations are used to elucidate the reaction mechanism and selectivity of BoxB catalyzed benzoyl-CoA epoxidation.
Benzoyl-CoA epoxidase is a dinuclear iron enzyme that catalyzes the epoxidation reaction of the aromatic ring of benzoyl-CoA with chemo-, regio- and stereo-selectivity. It has been suggested that this enzyme may also catalyze the deoxygenation reaction of epoxide, suggesting a unique bifunctionality among the diiron enzymes. We report a density functional theory study of this enzyme aimed at elucidating its mechanism and the various selectivities. The epoxidation is suggested to start with the binding of the O2 molecule to the diferrous center to generate a diferric peroxide complex, followed by concerted O–O bond cleavage and epoxide formation. Two different pathways have been located, leading to (2S,3R)-epoxy and (2R,3S)-epoxy products, with barriers of 17.6 and 20.4 kcal mol–1, respectively. The barrier difference is 2.8 kcal mol–1, corresponding to a diastereomeric excess of about 99 : 1. Further isomerization from epoxide to phenol is found to have quite a high barrier, which cannot compete with the product release step. After product release into solution, fast epoxide–oxepin isomerization and racemization can take place easily, leading to a racemic mixture of (2S,3R) and (2R,3S) products. The deoxygenation of epoxide to regenerate benzoyl-CoA by a diferrous form of the enzyme proceeds via a stepwise mechanism. The C2–O bond cleavage happens first, coupled with one electron transfer from one iron center to the substrate, to form a radical intermediate, which is followed by the second C3–O bond cleavage. The first step is rate-limiting with a barrier of only 10.8 kcal mol–1. Further experimental studies are encouraged to verify our results.
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Affiliation(s)
- Rong-Zhen Liao
- Key Laboratory for Large-Format Battery Materials and System , Ministry of Education , School of Chemistry and Chemical Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China .
| | - Per E M Siegbahn
- Department of Organic Chemistry , Arrhenius Laboratory , Stockholm University , SE-10691 Stockholm , Sweden .
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19
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Zanello P. The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part II. {[Fe2S2](SγCys)4} proteins. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.08.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Brossi MJDL, Mendes LW, Germano MG, Lima AB, Tsai SM. Assessment of bacterial bph gene in Amazonian dark earth and their adjacent soils. PLoS One 2014; 9:e99597. [PMID: 24927167 PMCID: PMC4057261 DOI: 10.1371/journal.pone.0099597] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 05/16/2014] [Indexed: 11/27/2022] Open
Abstract
Amazonian Anthrosols are known to harbour distinct and highly diverse microbial communities. As most of the current assessments of these communities are based on taxonomic profiles, the functional gene structure of these communities, such as those responsible for key steps in the carbon cycle, mostly remain elusive. To gain insights into the diversity of catabolic genes involved in the degradation of hydrocarbons in anthropogenic horizons, we analysed the bacterial bph gene community structure, composition and abundance using T-RFLP, 454-pyrosequencing and quantitative PCR essays, respectively. Soil samples were collected in two Brazilian Amazon Dark Earth (ADE) sites and at their corresponding non-anthropogenic adjacent soils (ADJ), under two different land use systems, secondary forest (SF) and manioc cultivation (M). Redundancy analysis of T-RFLP data revealed differences in bph gene structure according to both soil type and land use. Chemical properties of ADE soils, such as high organic carbon and organic matter, as well as effective cation exchange capacity and pH, were significantly correlated with the structure of bph communities. Also, the taxonomic affiliation of bph gene sequences revealed the segregation of community composition according to the soil type. Sequences at ADE sites were mostly affiliated to aromatic hydrocarbon degraders belonging to the genera Streptomyces, Sphingomonas, Rhodococcus, Mycobacterium, Conexibacter and Burkholderia. In both land use sites, shannon's diversity indices based on the bph gene data were higher in ADE than ADJ soils. Collectively, our findings provide evidence that specific properties in ADE soils shape the structure and composition of bph communities. These results provide a basis for further investigations focusing on the bio-exploration of novel enzymes with potential use in the biotechnology/biodegradation industry.
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Affiliation(s)
- Maria Julia de Lima Brossi
- Cellular and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, Brazil
- * E-mail:
| | - Lucas William Mendes
- Cellular and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, Brazil
| | | | - Amanda Barbosa Lima
- Cellular and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, Brazil
| | - Siu Mui Tsai
- Cellular and Molecular Biology Laboratory, Center for Nuclear Energy in Agriculture, University of São Paulo, Piracicaba, SP, Brazil
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Borzenkov IA, Zhurina MV, Tarasov AL, Belyaev SS, Dyubanov VG. Microbial potential for cleaning the oiled iron scale. APPL BIOCHEM MICRO+ 2014. [DOI: 10.1134/s0003683814030028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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22
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Sathyanarayanan N, Nagendra HG. Genome wide survey and molecular modeling of hypothetical proteins containing 2Fe-2S and FMN binding domains suggests Rieske Dioxygenase Activity highlighting their potential roles in bioremediation. Bioinformation 2014; 10:68-75. [PMID: 24616557 PMCID: PMC3937578 DOI: 10.6026/97320630010068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 01/26/2014] [Indexed: 12/02/2022] Open
Abstract
‘Conserved hypothetical’ proteins pose a challenge not just for functional genomics, but also to biology in general. As long as there
are hundreds of conserved proteins with unknown function in model organisms such as Escherichia coli, Bacillus subtilis or
Saccharomyces cerevisiae, any discussion towards a ‘complete’ understanding of these biological systems will remain a wishful
thinking. Insilico approaches exhibit great promise towards attempts that enable appreciating the plausible roles of these
hypothetical proteins. Among the majority of genomic proteins, two-thirds in unicellular organisms and more than 80% in
metazoa, are multi-domain proteins, created as a result of gene duplication events. Aromatic ring-hydroxylating dioxygenases, also
called Rieske dioxygenases (RDOs), are class of multi-domain proteins that catalyze the initial step in microbial aerobic
degradation of many aromatic compounds. Investigations here address the computational characterization of hypothetical proteins
containing Ferredoxin and Flavodoxin signatures. Consensus sequence of each class of oxidoreductase was obtained by a
phylogenetic analysis, involving clustering methods based on evolutionary relationship. A synthetic sequence was developed by
combining the consensus, which was used as the basis to search for their homologs via BLAST. The exercise yielded 129 multidomain
hypothetical proteins containing both 2Fe-2S (Ferredoxin) and FNR (Flavodoxin) domains. In the current study, 17 proteins
with N-terminus FNR domain and C-terminus 2Fe-2S domain are characterized, through homology modelling and docking
exercises which suggest dioxygenase activity indicate their plausible roles in degradation of aromatic moieties.
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Affiliation(s)
- Nitish Sathyanarayanan
- Department of Biotechnology, Sir M. Visvesvaraya Institute of Technology, Krishnadevarayanagar, Hunasamaranahalli, Bangalore 562 157 ; (Present Address) National Center for Biological Sciences, Tata Institute for Fundamental Research, GKVK Campus, Bellary Road, Bangalore 560065
| | - Holenarsipur Gundurao Nagendra
- Department of Biotechnology, Sir M. Visvesvaraya Institute of Technology, Krishnadevarayanagar, Hunasamaranahalli, Bangalore 562 157
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Khara P, Roy M, Chakraborty J, Ghosal D, Dutta TK. Functional characterization of diverse ring-hydroxylating oxygenases and induction of complex aromatic catabolic gene clusters in Sphingobium sp. PNB. FEBS Open Bio 2014; 4:290-300. [PMID: 24918041 PMCID: PMC4048848 DOI: 10.1016/j.fob.2014.03.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 03/03/2014] [Accepted: 03/03/2014] [Indexed: 11/27/2022] Open
Abstract
Sphingobium sp. PNB, like other sphingomonads, has multiple ring-hydroxylating oxygenase (RHO) genes. Three different fosmid clones have been sequenced to identify the putative genes responsible for the degradation of various aromatics in this bacterial strain. Comparison of the map of the catabolic genes with that of different sphingomonads revealed a similar arrangement of gene clusters that harbors seven sets of RHO terminal components and a sole set of electron transport (ET) proteins. The presence of distinctly conserved amino acid residues in ferredoxin and in silico molecular docking analyses of ferredoxin with the well characterized terminal oxygenase components indicated the structural uniqueness of the ET component in sphingomonads. The predicted substrate specificities, derived from the phylogenetic relationship of each of the RHOs, were examined based on transformation of putative substrates and their structural homologs by the recombinant strains expressing each of the oxygenases and the sole set of available ET proteins. The RHO AhdA1bA2b was functionally characterized for the first time and was found to be capable of transforming ethylbenzene, propylbenzene, cumene, p-cymene and biphenyl, in addition to a number of polycyclic aromatic hydrocarbons. Overexpression of aromatic catabolic genes in strain PNB, revealed by real-time PCR analyses, is a way forward to understand the complex regulation of degradative genes in sphingomonads.
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Affiliation(s)
| | | | | | | | - Tapan K. Dutta
- Department of Microbiology, Bose Institute, P-1/12 C.I.T. Scheme VII M, Kolkata 700054, India
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Purification and characterization of salicylate 5-hydroxylase, a three-component monooxygenase from Ralstonia sp. strain U2. Appl Microbiol Biotechnol 2013; 98:671-9. [DOI: 10.1007/s00253-013-4914-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 03/08/2013] [Accepted: 04/07/2013] [Indexed: 10/26/2022]
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Murdoch RW, Hay AG. Genetic and chemical characterization of ibuprofen degradation by Sphingomonas Ibu-2. MICROBIOLOGY (READING, ENGLAND) 2013; 159:621-632. [PMID: 23329679 PMCID: PMC4083657 DOI: 10.1099/mic.0.062273-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 11/05/2012] [Accepted: 01/14/2013] [Indexed: 01/03/2023]
Abstract
Sphingomonas Ibu-2 has the unusual ability to cleave the acid side chain from the pharmaceutical ibuprofen and related arylacetic acid derivatives to yield corresponding catechols under aerobic conditions via a previously uncharacterized mechanism. Screening a chromosomal library of Ibu-2 DNA in Escherichia coli EPI300 allowed us to identify one fosmid clone (pFOS3G7) that conferred the ability to metabolize ibuprofen to isobutylcatechol. Characterization of pFOS3G7 loss-of-function transposon mutants permitted identification of five ORFs, ipfABDEF, whose predicted amino acid sequences bore similarity to the large and small units of an aromatic dioxygenase (ipfAB), a sterol carrier protein X (SCPx) thiolase (ipfD), a domain of unknown function 35 (DUF35) protein (ipfE) and an aromatic CoA ligase (ipfF). Two additional ORFs, ipfH and ipfI, which encode putative ferredoxin reductase and ferredoxin components of an aromatic dioxygenase system, respectively, were also identified on pFOS3G7. Complementation of a markerless loss-of-function ipfD deletion mutant restored catechol production as did complementation of the ipfF Tn mutant. Expression of subcloned ipfABDEF alone in E. coli did not impart full metabolic activity unless coexpressed with ipfHI. CoA ligation followed by ring oxidation is common to phenylacetic acid pathways. However, the need for a putative SCPx thiolase (IpfD) and DUF35 protein (IpfE) in aerobic arylacetic acid degradation is unprecedented. This work provides preliminary insights into the mechanism behind this novel arylacetic acid-deacylating, catechol-generating activity.
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Affiliation(s)
- Robert W. Murdoch
- Graduate Program in Environmental Toxicology, Institute for Comparative and Environmental Toxicology, Cornell University, Ithaca, NY 14850, USA
| | - Anthony G. Hay
- Graduate Program in Environmental Toxicology, Institute for Comparative and Environmental Toxicology, Cornell University, Ithaca, NY 14850, USA
- Department of Microbiology, B53A Wing Hall, Cornell University, Ithaca, NY 14850, USA
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Xu F, Kong D, He X, Zhang Z, Han M, Xie X, Wang P, Cheng H, Tao M, Zhang L, Deng Z, Lin S. Characterization of streptonigrin biosynthesis reveals a cryptic carboxyl methylation and an unusual oxidative cleavage of a N-C bond. J Am Chem Soc 2013; 135:1739-48. [PMID: 23301954 DOI: 10.1021/ja3069243] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Streptonigrin (STN, 1) is a highly functionalized aminoquinone alkaloid with broad and potent antitumor activity. Here, we reported the biosynthetic gene cluster of STN identified by genome scanning of a STN producer Streptomyces flocculus CGMCC4.1223. This cluster consists of 48 genes determined by a series of gene inactivations. On the basis of the structures of intermediates and shunt products accumulated from five specific gene inactivation mutants and feeding experiments, the biosynthetic pathway was proposed, and the sequence of tailoring steps was preliminarily determined. In this pathway, a cryptic methylation of lavendamycin was genetically and biochemically characterized to be catalyzed by a leucine carboxyl methyltransferase StnF2. A [2Fe-2S](2+) cluster-containing aromatic ring dioxygenase StnB1/B2 system was biochemically characterized to catalyze a regiospecific cleavage of the N-C8' bond of the indole ring of the methyl ester of lavendamycin. This work provides opportunities to illuminate the enzymology of novel reactions involved in this pathway and to create, using genetic and chemo-enzymatic methods, new streptonigrinoid analogues as potential therapeutic agents.
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Affiliation(s)
- Fei Xu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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27
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Sathyanarayanan N, Nagendra HG. Analysis of multi-domain hypothetical proteins containing iron-sulphur clusters and fad ligands reveal rieske dioxygenase activity suggesting their plausible roles in bioremediation. Bioinformation 2012; 8:1154-61. [PMID: 23275712 PMCID: PMC3530884 DOI: 10.6026/97320630081154] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2012] [Accepted: 11/05/2012] [Indexed: 11/23/2022] Open
Abstract
'Conserved hypothetical' proteins pose a challenge not just for functional genomics, but also to biology in general. As long as there are hundreds of conserved proteins with unknown function in model organisms such as Escherichia coli, Bacillus subtilis or Saccharomyces cerevisiae, any discussion towards a 'complete' understanding of these biological systems will remain a wishful thinking. Insilico approaches exhibit great promise towards attempts that enable appreciating the plausible roles of these hypothetical proteins. Among the majority of genomic proteins, two-thirds in unicellular organisms and more than 80% in metazoa, are multi-domain proteins, created as a result of gene duplication events. Aromatic ring-hydroxylating dioxygenases, also called Rieske dioxygenases (RDOs), are class of multi-domain proteins that catalyze the initial step in microbial aerobic degradation of many aromatic compounds. Investigations here address the computational characterization of hypothetical proteins containing Ferredoxin and Flavodoxin signatures. Consensus sequence of each class of oxidoreductase was obtained by a phylogenetic analysis, involving clustering methods based on evolutionary relationship. A synthetic sequence was developed by combining the consensus, which was used as the basis to search for their homologs via BLAST. The exercise yielded 129 multidomain hypothetical proteins containing both 2Fe-2S (Ferredoxin) and FNR (Flavodoxin) domains. In the current study, 40 proteins with N-terminus 2Fe-2S domain and C-terminus FNR domain are characterized, through homology modelling and docking exercises which suggest dioxygenase activity indicating their plausible roles in degradation of aromatic moieties.
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Affiliation(s)
- Nitish Sathyanarayanan
- Department of Biotechnology, Sir M. Visvesvaraya Institute of Technology, Krishnadevarayanagar, Hunasamaranahalli, Bangalore 562 157
| | - Holenarasipur Gundurao Nagendra
- Department of Biotechnology, Sir M. Visvesvaraya Institute of Technology, Krishnadevarayanagar, Hunasamaranahalli, Bangalore 562 157
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28
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Epoxy Coenzyme A Thioester pathways for degradation of aromatic compounds. Appl Environ Microbiol 2012; 78:5043-51. [PMID: 22582071 DOI: 10.1128/aem.00633-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aromatic compounds (biogenic and anthropogenic) are abundant in the biosphere. Some of them are well-known environmental pollutants. Although the aromatic nucleus is relatively recalcitrant, microorganisms have developed various catabolic routes that enable complete biodegradation of aromatic compounds. The adopted degradation pathways depend on the availability of oxygen. Under oxic conditions, microorganisms utilize oxygen as a cosubstrate to activate and cleave the aromatic ring. In contrast, under anoxic conditions, the aromatic compounds are transformed to coenzyme A (CoA) thioesters followed by energy-consuming reduction of the ring. Eventually, the dearomatized ring is opened via a hydrolytic mechanism. Recently, novel catabolic pathways for the aerobic degradation of aromatic compounds were elucidated that differ significantly from the established catabolic routes. The new pathways were investigated in detail for the aerobic bacterial degradation of benzoate and phenylacetate. In both cases, the pathway is initiated by transforming the substrate to a CoA thioester and all the intermediates are bound by CoA. The subsequent reactions involve epoxidation of the aromatic ring followed by hydrolytic ring cleavage. Here we discuss the novel pathways, with a particular focus on their unique features and occurrence as well as ecological significance.
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29
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Characterization of biphenyl dioxygenase sequences and activities encoded by the metagenomes of highly polychlorobiphenyl-contaminated soils. Appl Environ Microbiol 2012; 78:2706-15. [PMID: 22327590 DOI: 10.1128/aem.07381-11] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Total extracted DNA from two heavily polychlorobiphenyl-contaminated soils was analyzed with respect to biphenyl dioxygenase sequences and activities. This was done by PCR amplification and cloning of a DNA segment encoding the active site of the enzyme. The translated sequences obtained fell into three similarity clusters (I to III). Sequence identities were high within but moderate or low between the clusters. Members of clusters I and II showed high sequence similarities with well-known biphenyl dioxygenases. Cluster III showed low (43%) sequence identity with a biphenyl dioxygenase from Rhodococcus jostii RHA1. Amplicons from the three clusters were used to reconstitute and express complete biphenyl dioxygenase operons. In most cases, the resulting hybrid dioxygenases were detected in cell extracts of the recombinant hosts. At least 83% of these enzymes were catalytically active. Several amino acid exchanges were identified that critically affected activity. Chlorobiphenyl turnover by the enzymes containing the prototype sequences of clusters I and II was characterized with 10 congeners that were major, minor, or not constituents of the contaminated soils. No direct correlations were observed between on-site concentrations and rates of productive dioxygenations of these chlorobiphenyls. The prototype enzymes displayed markedly different substrate and product ranges. The cluster II dioxygenase possessed a broader substrate spectrum toward the assayed congeners, whereas the cluster I enzyme was superior in the attack of ortho-chlorinated aromatic rings. These results demonstrate the feasibility of the applied approach to functionally characterize dioxygenase activities of soil metagenomes via amplification of incomplete genes.
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30
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Multiplicity of genes for aromatic ring-hydroxylating dioxygenases in Mycobacterium isolate KMS and their regulation. Biodegradation 2012; 23:585-96. [DOI: 10.1007/s10532-012-9535-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
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Abstract
Aromatic compounds are both common growth substrates for microorganisms and prominent environmental pollutants. The crucial step in their degradation is overcoming the resonance energy that stabilizes the ring structure. The classical strategy for degradation comprises an attack by oxygenases that hydroxylate and finally cleave the ring with the help of activated molecular oxygen. Here, we describe three alternative strategies used by microorganisms to degrade aromatic compounds. All three of these methods involve the use of CoA thioesters and ring cleavage by hydrolysis. However, these strategies are based on different ring activation mechanisms that consist of either formation of a non-aromatic ring-epoxide under oxic conditions, or reduction of the aromatic ring under anoxic conditions using one of two completely different systems.
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Teufel R, Gantert C, Voss M, Eisenreich W, Haehnel W, Fuchs G. Studies on the mechanism of ring hydrolysis in phenylacetate degradation: a metabolic branching point. J Biol Chem 2011; 286:11021-34. [PMID: 21296885 DOI: 10.1074/jbc.m110.196667] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The widespread, long sought-after bacterial aerobic phenylalanine/phenylacetate catabolic pathway has recently been elucidated. It proceeds via coenzyme A (CoA) thioesters and involves the epoxidation of the aromatic ring of phenylacetyl-CoA, subsequent isomerization to an uncommon seven-membered C-O-heterocycle (oxepin-CoA), and non-oxygenolytic ring cleavage. Here we characterize the hydrolytic oxepin-CoA ring cleavage catalyzed by the bifunctional fusion protein PaaZ. The enzyme consists of a C-terminal (R)-specific enoyl-CoA hydratase domain (formerly MaoC) that cleaves the ring and produces a highly reactive aldehyde and an N-terminal NADP(+)-dependent aldehyde dehydrogenase domain that oxidizes the aldehyde to 3-oxo-5,6-dehydrosuberyl-CoA. In many phenylacetate-utilizing bacteria, the genes for the pathway exist in a cluster that contains an NAD(+)-dependent aldehyde dehydrogenase in place of PaaZ, whereas the aldehyde-producing hydratase is encoded outside of the cluster. If not oxidized immediately, the reactive aldehyde condenses intramolecularly to a stable cyclic derivative that is largely prevented by PaaZ fusion in vivo. Interestingly, the derivative likely serves as the starting material for the synthesis of antibiotics (e.g. tropodithietic acid) and other tropone/tropolone related compounds as well as for ω-cycloheptyl fatty acids. Apparently, bacteria made a virtue out of the necessity of disposing the dead-end product with ring hydrolysis as a metabolic branching point.
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Affiliation(s)
- Robin Teufel
- Lehrstuhl Mikrobiologie, Fakultät Biologie, Universität Freiburg, Freiburg, Germany
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García LL, Rivas-Marín E, Floriano B, Bernhardt R, Ewen KM, Reyes-Ramírez F, Santero E. ThnY is a ferredoxin reductase-like iron-sulfur flavoprotein that has evolved to function as a regulator of tetralin biodegradation gene expression. J Biol Chem 2010; 286:1709-18. [PMID: 21068394 DOI: 10.1074/jbc.m110.184648] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previous genetic studies in Sphingomonas macrogolitabida strain TFA have established that expression of genes involved in tetralin biodegradation (thn genes) requires the function of the LysR type activator ThnR and also ThnY. Sequence comparison indicated that ThnY is homologous to bacterial oxygenase-coupled NAD(P)H-dependent ferredoxin reductases. However, ThnY showed substitutions in highly conserved positions of the pyridine nucleotide binding domain of these ferredoxin reductases. ThnY expression is co-regulated with all other genes required for tetralin biodegradation, and presumably thnY is part of the thnCA3A4RY operon. ThnY has been purified, and its biochemical and functional properties were characterized. ThnY was found to be a monomeric orange-brown iron-sulfur flavoprotein (estimated mass of 37,000 Da) containing one non-covalently attached flavin adenine dinucleotide and one plant type ferredoxin 2Fe-2S cluster. It can be efficiently reduced by dithionite, but reduction by pyridine nucleotides was very poor. Consistently, ThnY-dependent reduction of cytochrome c, ferricyanide, or 2,6-dichlorophenolindophenol using NAD(P)H as the electron donor was undetectable or very weak. The addition of ThnY to electrophoretic mobility shift assays containing ThnR and a probe bearing two thn divergent promoters resulted in a 3-fold increase in protein-DNA complex formation affinity, which indicates that ThnY directly promotes thn transcription activation by ThnR.
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Affiliation(s)
- Laura Ledesma García
- Centro Andaluz de Biología del Desarrollo, Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Carretera de Utrera Km. 1, 41013 Seville, Spain
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Identification and characterization of genes involved in naphthalene degradation in Rhodococcus opacus R7. Appl Microbiol Biotechnol 2010; 87:297-308. [PMID: 20195856 DOI: 10.1007/s00253-010-2497-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 02/05/2010] [Accepted: 02/06/2010] [Indexed: 10/19/2022]
Abstract
Rhodococcus opacus R7 is a naphthalene-degrading microorganism which is also able to grow on o-xylene. This work describes the isolation and analysis of two new genomic regions in which genes involved in naphthalene (nar gene cluster) and salicylate (gen gene cluster) degradation are located. In the nar gene cluster we found: two genes encoding the large (narAa) and the small (narAb) components of the naphthalene dioxygenase, three genes (rub1, rub2, rub1bis) encoding three rubredoxins, an orf (orf7) associated to the complex encoding a protein of unknown function, two regulatory genes (narR1, narR2), a gene (narB) encoding the naphthalene dihydrodiol dehydrogenase and six orfs (orf1, orf2, orf3, orf4, orf5, orf6) encoding proteins of unknown function. In the gen gene cluster, we found the following genes: two genes encoding the salicylate CoA ligase and the salicylate CoA synthetase (genA and genB), respectively, a gene (genC) encoding a salicylate hydroxylase, a gene (genH) encoding a gentisate 1,2-dioxygenase, a gene (genI) encoding a 3-maleylpyruvate isomerase, and a gene (genL) encoding a protein of unknown function. The transcription of some genes of R. opacus R7 strain grown on different substrates was also investigated to evaluate the expression of the two gene clusters after cDNA preparations.
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Characterization of 2T engine oil degrading indigenous bacteria, isolated from high altitude (Mussoorie), India. World J Microbiol Biotechnol 2010. [DOI: 10.1007/s11274-010-0316-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Peng RH, Xiong AS, Xue Y, Fu XY, Gao F, Zhao W, Tian YS, Yao QH. A profile of ring-hydroxylating oxygenases that degrade aromatic pollutants. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2010; 206:65-94. [PMID: 20652669 DOI: 10.1007/978-1-4419-6260-7_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Numerous aromatic compounds are pollutants to which exposure exists or is possible, and are of concern because they are mutagenic, carcinogenic, or display other toxic characteristics. Depending on the types of dioxygenation reactions of which microorganisms are capable, they utilize ring-hydroxylating oxygenases (RHOs) to initiate the degradation and detoxification of such aromatic compound pollutants. Gene families encoding for RHOs appear to be most common in bacteria. Oxygenases are important in degrading both natural and synthetic aromatic compounds and are particularly important for their role in degrading toxic pollutants; for this reason, it is useful for environmental scientists and others to understand more of their characteristics and capabilities. It is the purpose of this review to address RHOs and to describe much of their known character, starting with a review as to how RHOs are classified. A comprehensive phylogenetic analysis has revealed that all RHOs are, in some measure, related, presumably by divergent evolution from a common ancestor, and this is reflected in how they are classified. After we describe RHO classification schemes, we address the relationship between RHO structure and function. Structural differences affect substrate specificity and product formation. In the alpha subunit of the known terminal oxygenase of RHOs, there is a catalytic domain with a mononuclear iron center that serves as a substrate-binding site and a Rieske domain that retains a [2Fe-2S] cluster that acts as an entity of electron transfer for the mononuclear iron center. Oxygen activation and substrate dihydroxylation occurring at the catalytic domain are dependent on the binding of substrate at the active site and the redox state of the Rieske center. The electron transfer from NADH to the catalytic pocket of RHO and catalyzing mechanism of RHOs is depicted in our review and is based on the results of recent studies. Electron transfer involving the RHO system typically involves four steps: NADH-ferredoxin reductase receives two electrons from NADH; ferredoxin binds with NADH-ferredoxin reductase and accepts electron from it; the reduced ferredoxin dissociates from NADH-ferredoxin reductase and shuttles the electron to the Rieske domain of the terminal oxygenase; the Rieske cluster donates electrons to O2 through the mononuclear iron. On the basis of crystal structure studies, it has been proposed that the broad specificity of the RHOs results from the large size and specific topology of its hydrophobic substrate-binding pocket. Several amino acids that determine the substrate specificity and enantioselectivity of RHOs have been identified through sequence comparison and site-directed mutagenesis at the active site. Exploiting the crystal structure data and the available active site information, engineered RHO enzymes have been and can be designed to improve their capacity to degrade environmental pollutants. Such attempts to enhance degradation capabilities of RHOs have been made. Dioxygenases have been modified to improve the degradation capacities toward PCBs, PAHs, dioxins, and some other aromatic hydrocarbons. We hope that the results of this review and future research on enhancing RHOs will promote their expanded usage and effectiveness for successfully degrading environmental aromatic pollutants.
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Affiliation(s)
- Ri-He Peng
- Shanghai Key Laboratory of Agricultural Genetics and Breeding, Agro-Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, 2901 Beidi Rd, Shanghai, People's Republic of China
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Morimoto S, Fujii T. A new approach to retrieve full lengths of functional genes from soil by PCR-DGGE and metagenome walking. Appl Microbiol Biotechnol 2009; 83:389-96. [PMID: 19370345 DOI: 10.1007/s00253-009-1992-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2009] [Revised: 03/26/2009] [Accepted: 03/27/2009] [Indexed: 10/20/2022]
Abstract
Metagenomes are a vast genetic resource, and various approaches have been developed to explore them. Here, we present a new approach to retrieve full lengths of functional genes from soil DNA using PCR-denaturing gradient gel electrophoresis (DGGE) followed by metagenome walking. Partial fragments of benzoate 1,2-dioxygenase alpha subunit gene (benA) were detected from a 3-chlorobenzoate (3CB)-dosed soil by PCR-DGGE, and one DGGE band induced by 3CB was used as a target fragment for metagenome walking. The walking retrieved the flanking regions of the target fragment from the soil DNA, resulting in recovery of the full length of benA and also downstream gene (benB). The same strategy retrieved another gene, tfdC, and a complete tfdC and two downstream genes were obtained from the same soil. PCR-DGGE allows screening for target genes based on their potential for degrading contaminants in the environment. This feature provides an advantage over other existing metagenomic approaches.
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Affiliation(s)
- Sho Morimoto
- National Institute for Agro-Environmental Sciences, 3-1-3 Kannondai, Tsukuba, Ibaraki, 305-8604, Japan.
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Characterization of a ring-hydroxylating dioxygenase from phenanthrene-degrading Sphingomonas sp. strain LH128 able to oxidize benz[a]anthracene. Appl Microbiol Biotechnol 2009; 83:465-75. [PMID: 19172265 DOI: 10.1007/s00253-009-1858-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2008] [Revised: 01/03/2009] [Accepted: 01/05/2009] [Indexed: 10/21/2022]
Abstract
Sphingomonas sp. strain LH128 was isolated from a polycyclic aromatic hydrocarbon (PAH)-contaminated soil using phenanthrene as the sole source of carbon and energy. A dioxygenase complex, phnA1fA2f, encoding the alpha and beta subunit of a terminal dioxygenase responsible for the initial attack on PAHs, was identified and isolated from this strain. PhnA1f showed 98%, 78%, and 78% identity to the alpha subunit of PAH dioxygenase from Novosphingobium aromaticivorans strain F199, Sphingomonas sp. strain CHY-1, and Sphingobium yanoikuyae strain B1, respectively. When overexpressed in Escherichia coli, PhnA1fA2f was able to oxidize low-molecular-weight PAHs, chlorinated biphenyls, dibenzo-p-dioxin, and the high-molecular-weight PAHs benz[a]anthracene, chrysene, and pyrene. The action of PhnA1fA2f on benz[a]anthracene produced two benz[a]anthracene dihydrodiols.
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Enzymatic properties of terephthalate 1,2-dioxygenase of Comamonas sp. strain E6. Biosci Biotechnol Biochem 2008; 72:2335-41. [PMID: 18776687 DOI: 10.1271/bbb.80236] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The tphA1 II and tphA2 II A3 II genes of Comamonas sp. E6 perhaps code for the terephthalate (TPA) 1,2-dioxygenase (TPADO). To characterize E6 TPADO, these genes were expressed in a His-tagged form in Escherichia coli, and the recombinant proteins were purified. TPADO activity was reconstituted from TphA1 II and TphA2 II A3 II, indicating that TPADO consists of a reductase (TphA1 II) and a terminal oxygenase component (TphA2 II and TphA3 II). TphA1(II) contains FAD, and the presence of a plant-type [2Fe-2S] cluster was suggested. These results indicate that TPADO is a class IB aromatic ring-hydroxylating dioxygenase. NADH and NADPH were effective as electron donors for TphA1 II, but NADPH appeared to be the physiological electron donor, based on the kinetic parameters. TPADO showed activity only toward TPA, and Fe2+ was required for it. The Km values for TPA and the Vmax were determined to be 72+/-6 microM and 9.87+/-0.06 U/mg respectively.
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Peng RH, Xiong AS, Xue Y, Fu XY, Gao F, Zhao W, Tian YS, Yao QH. Microbial biodegradation of polyaromatic hydrocarbons. FEMS Microbiol Rev 2008; 32:927-55. [PMID: 18662317 DOI: 10.1111/j.1574-6976.2008.00127.x] [Citation(s) in RCA: 392] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are widespread in various ecosystems and are pollutants of great concern due to their potential toxicity, mutagenicity and carcinogenicity. Because of their hydrophobic nature, most PAHs bind to particulates in soil and sediments, rendering them less available for biological uptake. Microbial degradation represents the major mechanism responsible for the ecological recovery of PAH-contaminated sites. The goal of this review is to provide an outline of the current knowledge of microbial PAH catabolism. In the past decade, the genetic regulation of the pathway involved in naphthalene degradation by different gram-negative and gram-positive bacteria was studied in great detail. Based on both genomic and proteomic data, a deeper understanding of some high-molecular-weight PAH degradation pathways in bacteria was provided. The ability of nonligninolytic and ligninolytic fungi to transform or metabolize PAH pollutants has received considerable attention, and the biochemical principles underlying the degradation of PAHs were examined. In addition, this review summarizes the information known about the biochemical processes that determine the fate of the individual components of PAH mixtures in polluted ecosystems. A deeper understanding of the microorganism-mediated mechanisms of catalysis of PAHs will facilitate the development of new methods to enhance the bioremediation of PAH-contaminated sites.
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Affiliation(s)
- Ri-He Peng
- Shanghai Key Laboratory of Agricultural Genetics and Breeding, Agro-Biotechnology Research Institute, Shanghai Academy of Agricultural Sciences, Shanghai, China
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Parales RE, Parales JV, Pelletier DA, Ditty JL. Diversity of microbial toluene degradation pathways. ADVANCES IN APPLIED MICROBIOLOGY 2008; 64:1-73, 2 p following 264. [PMID: 18485280 DOI: 10.1016/s0065-2164(08)00401-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- R E Parales
- Department of Microbiology, University of California, Davis, California 95616, USA
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Benzoyl-coenzyme A thioesterase of Azoarcus evansii: properties and function. Arch Microbiol 2008; 190:451-60. [PMID: 18542924 DOI: 10.1007/s00203-008-0393-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Revised: 04/23/2008] [Accepted: 05/19/2008] [Indexed: 10/22/2022]
Abstract
The aerobic benzoate metabolism in Azoarcus evansii follows an unusual route. The intermediates of the pathway are processed as coenzyme A (CoA) thioesters and the cleavage of the aromatic ring is non-oxygenolytic. The enzymes of this pathway are encoded by the box gene cluster which harbors a gene, orf1, coding for a putative thioesterase. Benzoyl-CoA thioesterase activity (20 nmol min(-1) mg(-1) protein) was present in cells grown aerobically on benzoate, but was lacking in cells grown on other aromatic or aliphatic substrates under oxic or anoxic conditions. The gene was cloned and overexpressed in Escherichia coli to produce a C-terminal His-tag fusion protein. The recombinant enzyme was a homotetramer of 16 kDa subunits. It catalyzed not only the hydrolysis of benzoyl-CoA, but also of 2,3-dihydro-2,3-dihydroxybenzoyl-CoA, the second intermediate in the pathway. The enzyme exhibited higher activity with mono-substituted derivatives of benzoyl-CoA, showing highest activity with 4-hydroxybenzoyl-CoA. Di-substituted derivatives of benzoyl-CoA, phenylacetyl-CoA, and aliphatic CoA thioesters were not hydrolyzed but some acted as inhibitors. The thioesterase appears to protect the cell from CoA pool depletion. It may constitute the prototype of a new subfamily within the hotdog fold enzyme superfamily.
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Two angular dioxygenases contribute to the metabolic versatility of dibenzofuran-degrading Rhodococcus sp. strain HA01. Appl Environ Microbiol 2008; 74:3812-22. [PMID: 18441103 DOI: 10.1128/aem.00226-08] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Rhodococcus sp. strain HA01, isolated through its ability to utilize dibenzofuran (DBF) as the sole carbon and energy source, was also capable, albeit with low activity, of transforming dibenzo-p-dioxin (DD). This strain could also transform 3-chlorodibenzofuran (3CDBF), mainly by angular oxygenation at the ether bond-carrying carbon (the angular position) and an adjacent carbon atom, to 4-chlorosalicylate as the end product. Similarly, 2-chlorodibenzofuran (2CDBF) was transformed to 5-chlorosalicylate. However, lateral oxygenation at the 3,4-positions was also observed and yielded the novel product 2-chloro-3,4-dihydro-3,4-dihydroxydibenzofuran. Two gene clusters encoding enzymes for angular oxygenation (dfdA1A2A3A4 and dbfA1A2) were isolated, and expression of both was observed during growth on DBF. Heterologous expression revealed that both oxygenase systems catalyze angular oxygenation of DBF and DD but exhibited complementary substrate specificity with respect to CDBF transformation. While DfdA1A2A3A4 oxygenase, with high similarity to DfdA1A2A3A4 oxygenase from Terrabacter sp. strain YK3, transforms 3CDBF by angular dioxygenation at a rate of 29% +/- 4% that of DBF, 2CDBF was not transformed. In contrast, DbfA1A2 oxygenase, with high similarity to the DbfA1A2 oxygenase from Terrabacter sp. strain DBF63, exhibited complementary activity with angular oxygenase activity against 2CDBF but negligible activity against 3CDBF. Thus, Rhodococcus sp. strain HA01 constitutes the first described example of a bacterial strain where coexpression of two angular dioxygenases was observed. Such complementary activity allows for the efficient transformation of chlorinated DBFs.
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Kim SH, Hisano T, Iwasaki W, Ebihara A, Miki K. Crystal structure of the flavin reductase component (HpaC) of 4-hydroxyphenylacetate 3-monooxygenase from Thermus thermophilus HB8: Structural basis for the flavin affinity. Proteins 2008; 70:718-30. [PMID: 17729270 DOI: 10.1002/prot.21534] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The two-component enzyme, 4-hydroxyphenylacetate 3-monooxygenase, catalyzes the conversion of 4-hydroxyphenylacetate to 3,4-dihydroxyphenylacetate. In the overall reaction, the oxygenase component (HpaB) introduces a hydroxyl group into the benzene ring of 4-hydroxyphenylacetate using molecular oxygen and reduced flavin, while the reductase component (HpaC) provides free reduced flavins for HpaB. The crystal structures of HpaC from Thermus thermophilus HB8 in the ligand-free form, the FAD-containing form, and the ternary complex with FAD and NAD(+) were determined. In the ligand-free form, two large grooves are present at the dimer interface, and are occupied by water molecules. A structural analysis of HpaC containing FAD revealed that FAD has a low occupancy, indicating that it is not tightly bound to HpaC. This was further confirmed in flavin dissociation experiments, showing that FAD can be released from HpaC. The structure of the ternary complex revealed that FAD and NAD(+) are bound in the groove in the extended and folded conformation, respectively. The nicotinamide ring of NAD(+) is sandwiched between the adenine ring of NAD(+) and the isoalloxazine ring of FAD. The distance between N5 of the isoalloxazine ring and C4 of the nicotinamide ring is about 3.3 A, sufficient to permit hydride transfer. The structures of these three states are essentially identical, however, the side chains of several residues show small conformational changes, indicating an induced fit upon binding of NADH. Inactivity with respect to NADPH can be explained as instability of the binding of NADPH with the negatively charged 2'-phosphate group buried inside the complex, as well as a possible repulsive effect by the dipole of helix alpha1. A comparison of the binding mode of FAD with that in PheA2 from Bacillus thermoglucosidasius A7, which contains FAD as a prosthetic group, reveals remarkable conformational differences in a less conserved loop region (Gly83-Gly94) involved in the binding of the AMP moiety of FAD. These data suggest that variations in the affinities for FAD in the reductases of the two-component flavin-diffusible monooxygenase family may be attributed to difference in the interaction between the AMP moiety of FAD and the less conserved loop region which possibly shows structural divergence.
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Affiliation(s)
- Seong-Hoon Kim
- SPring-8 Center, RIKEN Harima Institute, Koto 1-1-1, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
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Phenylacetate metabolism in thermophiles: characterization of phenylacetate-CoA ligase, the initial enzyme of the hybrid pathway in Thermus thermophilus. Curr Microbiol 2008; 57:27-32. [PMID: 18414813 DOI: 10.1007/s00284-008-9147-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Accepted: 02/13/2008] [Indexed: 10/22/2022]
Abstract
Phenylacetate-CoA ligase (E.C. 6.2.1.30), the initial enzyme in the metabolism of phenylacetate, was studied in Thermus thermophilus strain HB27. Enzymatic activity was upregulated during growth on phenylacetate or phenylalanine. The phenylacetate-CoA ligase gene (paaK) was cloned and heterologously expressed in Escherichia coli and the recombinant protein was purified. The enzyme catalyzed phenylacetate + CoA + MgATP --> phenylacetyl-CoA + AMP + MgPP(i) with a V(max) of 24 micromol/min/mg protein at a temperature optimum of 75 degrees C. The apparent K(m) values for ATP, CoA, and phenylacetate were 6, 30, and 50 microM: , respectively. The protein was highly specific toward phenylacetate and showed only low activity with 4-hydroxyphenylacetate. Despite an amino acid sequence identity of >50% with its mesophilic homologues, phenylacetate-CoA ligase was heat stable. The genome contained further homologues of genes, which are postulated to be involved in the CoA ester-dependent metabolic pathway of phenylacetate (hybrid pathway). Enzymes of this thermophile are expected to be robust and might be useful for further studies of this yet unresolved pathway.
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Kweon O, Kim SJ, Baek S, Chae JC, Adjei MD, Baek DH, Kim YC, Cerniglia CE. A new classification system for bacterial Rieske non-heme iron aromatic ring-hydroxylating oxygenases. BMC BIOCHEMISTRY 2008; 9:11. [PMID: 18387195 PMCID: PMC2358900 DOI: 10.1186/1471-2091-9-11] [Citation(s) in RCA: 101] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2008] [Accepted: 04/03/2008] [Indexed: 11/18/2022]
Abstract
BACKGROUND Rieske non-heme iron aromatic ring-hydroxylating oxygenases (RHOs) are multi-component enzyme systems that are remarkably diverse in bacteria isolated from diverse habitats. Since the first classification in 1990, there has been a need to devise a new classification scheme for these enzymes because many RHOs have been discovered, which do not belong to any group in the previous classification. Here, we present a scheme for classification of RHOs reflecting new sequence information and interactions between RHO enzyme components. RESULT We have analyzed a total of 130 RHO enzymes in which 25 well-characterized RHO enzymes were used as standards to test our hypothesis for the proposed classification system. From the sequence analysis of electron transport chain (ETC) components of the standard RHOs, we extracted classification keys that reflect not only the phylogenetic affiliation within each component but also relationship among components. Oxygenase components of standard RHOs were phylogenetically classified into 10 groups with the classification keys derived from ETC components. This phylogenetic classification scheme was converted to a new systematic classification consisting of 5 distinct types. The new classification system was statistically examined to justify its stability. Type I represents two-component RHO systems that consist of an oxygenase and an FNRC-type reductase. Type II contains other two-component RHO systems that consist of an oxygenase and an FNRN-type reductase. Type III represents a group of three-component RHO systems that consist of an oxygenase, a [2Fe-2S]-type ferredoxin and an FNRN-type reductase. Type IV represents another three-component systems that consist of oxygenase, [2Fe-2S]-type ferredoxin and GR-type reductase. Type V represents another different three-component systems that consist of an oxygenase, a [3Fe-4S]-type ferredoxin and a GR-type reductase. CONCLUSION The new classification system provides the following features. First, the new classification system analyzes RHO enzymes as a whole. RwithSecond, the new classification system is not static but responds dynamically to the growing pool of RHO enzymes. Third, our classification can be applied reliably to the classification of incomplete RHOs. Fourth, the classification has direct applicability to experimental work. Fifth, the system provides new insights into the evolution of RHO systems based on enzyme interaction.
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Affiliation(s)
- Ohgew Kweon
- Microbiology Division, National Center for Toxicological Research/U.S. FDA, Jefferson, AR 72079, USA
| | - Seong-Jae Kim
- Microbiology Division, National Center for Toxicological Research/U.S. FDA, Jefferson, AR 72079, USA
| | - Songjoon Baek
- Division of Personalized Nutrition & Medicine, National Center for Toxicological Research/U.S. FDA, Jefferson, AR 72079, USA
| | - Jong-Chan Chae
- Biotechnology Center for Agriculture and the Environment, Cook College, Rutgers University, New Brunswick, NJ 08901, USA
| | - Michael D Adjei
- Department of Health Norfolk Department of Public Health Bureau of Laboratories, Norfolk, VA 23510, USA
| | - Dong-Heon Baek
- Department of Oral Microbiology and Immunology, School of Dentistry, Dankook University, Chonan 330-714, Republic of Korea
| | - Young-Chang Kim
- School of Life Science, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
| | - Carl E Cerniglia
- Microbiology Division, National Center for Toxicological Research/U.S. FDA, Jefferson, AR 72079, USA
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Boxhammer S, Glaser S, Kühl A, Wagner AK, Schmidt CL. Characterization of the recombinant Rieske [2Fe-2S] proteins HcaC and YeaW from E. coli. Biometals 2008; 21:459-67. [PMID: 18286376 DOI: 10.1007/s10534-008-9134-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 02/05/2008] [Indexed: 11/25/2022]
Abstract
Three genes within the genome of E. coli K12 are predicted to encode proteins containing the typical Rieske iron-sulfur cluster-binding motifs. Two of these, hcaC and yeaW, were overexpressed in E. coli BL21 and Tuner (DE3) pLacI. The recombinant proteins were purified and analyzed by UV/Vis- and EPR-spectroscopy. HcaC and YeaW display the typical redox-dependent UV/Vis-spectra of iron-sulfur proteins. The EPR spectrum of reduced HcaC shows characteristic g-values of a Rieske cluster whereas the g-values for YeaW are close to the upper limit for this type of iron-sulfur cluster. Both iron-sulfur clusters could be reduced by dithionite, but not by ascorbate, confirming their classification as low-potential Rieske proteins as derived from the amino acid sequences. A phylogenetic analysis of the two proteins reveals that HcaC clearly segregates with the Rieske ferredoxins of class IIB oxygenases whereas the classification of YeaW remains doubtful.
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Affiliation(s)
- S Boxhammer
- Center for Structural and Cell Biology in Medicine, Institute of Biochemistry, University of Lübeck, Ratzeburger Allee 160, Lubeck, Germany
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Jouanneau Y, Micoud J, Meyer C. Purification and characterization of a three-component salicylate 1-hydroxylase from Sphingomonas sp. strain CHY-1. Appl Environ Microbiol 2007; 73:7515-21. [PMID: 17905882 PMCID: PMC2168081 DOI: 10.1128/aem.01519-07] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the bacterial degradation of polycyclic aromatic hydrocarbons (PAHs), salicylate hydroxylases catalyze essential reactions at the junction between the so-called upper and lower catabolic pathways. Unlike the salicylate 1-hydroxylase from pseudomonads, which is a well-characterized flavoprotein, the enzyme found in sphingomonads appears to be a three-component Fe-S protein complex, which so far has not been characterized. Here, the salicylate 1-hydroxylase from Sphingomonas sp. strain CHY-1 was purified, and its biochemical and catalytic properties were characterized. The oxygenase component, designated PhnII, exhibited an alpha3beta3 heterohexameric structure and contained one Rieske-type [2Fe-2S] cluster and one mononuclear iron per alpha subunit. In the presence of purified reductase (PhnA4) and ferredoxin (PhnA3) components, PhnII catalyzed the hydroxylation of salicylate to catechol with a maximal specific activity of 0.89 U/mg and showed an apparent Km for salicylate of 1.1 +/- 0.2 microM. The hydroxylase exhibited similar activity levels with methylsalicylates and low activity with salicylate analogues bearing additional hydroxyl or electron-withdrawing substituents. PhnII converted anthranilate to 2-aminophenol and exhibited a relatively low affinity for this substrate (Km, 28 +/- 6 microM). 1-Hydroxy-2-naphthoate, which is an intermediate in phenanthrene degradation, was not hydroxylated by PhnII, but it induced a high rate of uncoupled oxidation of NADH. It also exerted strong competitive inhibition of salicylate hydroxylation, with a Ki of 0.68 microM. The properties of this three-component hydroxylase are compared with those of analogous bacterial hydroxylases and are discussed in light of our current knowledge of PAH degradation by sphingomonads.
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Affiliation(s)
- Yves Jouanneau
- LCBM/iRTSV, CEA-Grenoble, F-38054 Grenoble Cedex 9, France.
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de Cárcer DA, Martín M, Karlson U, Rivilla R. Changes in bacterial populations and in biphenyl dioxygenase gene diversity in a polychlorinated biphenyl-polluted soil after introduction of willow trees for rhizoremediation. Appl Environ Microbiol 2007; 73:6224-32. [PMID: 17693557 PMCID: PMC2075012 DOI: 10.1128/aem.01254-07] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study was to analyze the structural and functional changes occurring in a polychlorinated-biphenyl (PCB)-contaminated soil ecosystem after the introduction of a suitable host plant for rhizoremediation (Salix viminalis). We have studied the populations and phylogenetic distribution of key bacterial groups (Alpha- and Betaproteobacteria, Acidobacteria, and Actinobacteria) and the genes encoding iron-sulfur protein alpha (ISPalpha) subunits of the toluene/biphenyl dioxygenases in soil and rhizosphere by screening gene libraries using temperature gradient gel electrophoresis. The results, based on the analysis of 415 clones grouped into 133 operational taxonomic units that were sequence analyzed (>128 kbp), show that the rhizospheric bacterial community which evolved from the native soil community during the development of the root system was distinct from the soil community for all groups studied except for the Actinobacteria. Proteobacteria were enriched in the rhizosphere and dominated both in rhizosphere and soil. There was a higher than expected abundance of Betaproteobacteria in the native and in the planted PCB-polluted soil. The ISPalpha sequences retrieved indicate a high degree of catabolic and phylogenetic diversity. Many sequences clustered with biphenyl dioxygenase sequences from gram-negative bacteria. A distinct cluster that was composed of sequences from this study, some previously described environmental sequences, and a putative ISPalpha from Sphingomonas wittichii RW1 seems to contain greater diversity than the presently recognized toluene/biphenyl dioxygenase subfamily. Moreover, the rhizosphere selected for two ISPalpha sequences that accounted for almost 60% of the gene library and were very similar to sequences harbored by Pseudomonas species.
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Weelink SAB, Tan NCG, Ten Broeke H, van Doesburg W, Langenhoff AAM, Gerritse J, Stams AJM. Physiological and phylogenetic characterization of a stable benzene-degrading, chlorate-reducing microbial community. FEMS Microbiol Ecol 2007; 60:312-21. [PMID: 17386037 DOI: 10.1111/j.1574-6941.2007.00289.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene degradation. Denaturing gradient gel electrophoresis of part of the 16S rRNA gene, cloning and sequencing showed that the culture had a stable composition after the seventh transfer. Five bacterial clones were further analyzed. Two clones corresponded to bacteria closely related to Alicycliphilus denitrificans K601. The three other clones corresponded to bacteria closely related to Zoogloea resiniphila PIV-3A2w, Mesorhizobium sp. WG and Stenotrophomonas acidaminiphila. DGGE analysis of cultures grown with different electron donors and acceptors indicated that the bacterium related to Alicycliphilus denitrificans K601 is able to degrade benzene coupled to chlorate reduction. The role of the other bacteria could not be conclusively determined. The bacterium related to Mesorhizobium sp. WG can be enriched with benzene and oxygen, but not with acetate and chlorate, while the bacterium related to Stenotrophomonas acidaminophila grows with acetate and chlorate, but not with benzene and oxygen. As oxygen is produced during chlorate reduction, an aerobic pathway of benzene degradation is most likely.
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Affiliation(s)
- Sander A B Weelink
- Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands
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