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Guo L, Ouyang X, Wang W, Qiu X, Zhao YL, Xu P, Tang H. Fine-tuning an aromatic ring-hydroxylating oxygenase to degrade high molecular weight polycyclic aromatic hydrocarbon. J Biol Chem 2024; 300:107343. [PMID: 38705395 PMCID: PMC11176777 DOI: 10.1016/j.jbc.2024.107343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/25/2024] [Accepted: 04/29/2024] [Indexed: 05/07/2024] Open
Abstract
Rieske nonheme iron aromatic ring-hydroxylating oxygenases (RHOs) play pivotal roles in determining the substrate preferences of polycyclic aromatic hydrocarbon (PAH) degraders. However, their potential to degrade high molecular weight PAHs (HMW-PAHs) has been relatively unexplored. NarA2B2 is an RHO derived from a thermophilic Hydrogenibacillus sp. strain N12. In this study, we have identified four "hotspot" residues (V236, Y300, W316, and L375) that may hinder the catalytic capacity of NarA2B2 when it comes to HMW-PAHs. By employing structure-guided rational enzyme engineering, we successfully modified NarA2B2, resulting in NarA2B2 variants capable of catalyzing the degradation of six different types of HMW-PAHs, including pyrene, fluoranthene, chrysene, benzo[a]anthracene, benzo[b]fluoranthene, and benzo[a]pyrene. Three representative variants, NarA2B2W316I, NarA2B2Y300F-W316I, and NarA2B2V236A-W316I-L375F, not only maintain their abilities to degrade low-molecular-weight PAHs (LMW-PAHs) but also exhibited 2 to 4 times higher degradation efficiency for HMW-PAHs in comparison to another isozyme, NarAaAb. Computational analysis of the NarA2B2 variants predicts that these modifications alter the size and hydrophobicity of the active site pocket making it more suitable for HMW-PAHs. These findings provide a comprehensive understanding of the relationship between three-dimensional structure and functionality, thereby opening up possibilities for designing improved RHOs that can be more effectively used in the bioremediation of PAHs.
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Affiliation(s)
- Lihua Guo
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Xingyu Ouyang
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Weiwei Wang
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Xiaoyu Qiu
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Yi-Lei Zhao
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, and School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China.
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Guo L, Ouyang X, Wang W, Huang Y, Qiu X, Xu P, Tang H. Characterization of a novel aromatic ring-hydroxylating oxygenase, NarA2B2, from thermophilic Hydrogenibacillus sp. strain N12. Appl Environ Microbiol 2023; 89:e0086523. [PMID: 37819076 PMCID: PMC10617421 DOI: 10.1128/aem.00865-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 08/11/2023] [Indexed: 10/13/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are harmful to human health due to their carcinogenic, teratogenic, and mutagenic effects. A thermophilic Hydrogenibacillus sp. strain N12 capable of degrading a variety of PAHs and derivatives was previously isolated. In this study, an aromatic ring-hydroxylating oxygenase, NarA2B2, was identified from strain N12, with substrate specificity including naphthalene, phenanthrene, dibenzothiophene, fluorene, acenaphthene, carbazole, biphenyl, and pyrene. NarA2B2 was proposed to add one or two atoms of molecular oxygen to the substrate and catalyze biphenyl at C-2, 2 or C-3, 4 positions with different characteristics than before. The key catalytic amino acids, H222, H227, and D379, were identified as playing a pivotal role in the formation of the 2-his-1-carboxylate facial triad. Furthermore, we conducted molecular docking and molecular dynamics simulations, notably, D219 enhanced the stability of the iron center by forming two stable hydrogen bonds with H222, while the mutation of F216, T223, and H302 modulated the catalytic activity by altering the pocket's size and shape. Compared to the wild-type (WT) enzyme, the degradation ratios of acenaphthene by F216A, T223A, and H302A had an improvement of 23.08%, 26.87%, and 29.52%, the degradation ratios of naphthalene by T223A and H302A had an improvement of 51.30% and 65.17%, while the degradation ratio of biphenyl by V236A had an improvement of 77.94%. The purified NarA2B2 was oxygen-sensitive when it was incubated with L-ascorbic acid in an anaerobic environment, and its catalytic activity was restored in vitro. These results contribute to a better understanding of the molecular mechanism responsible for PAHs' degradation in thermophilic microorganisms.IMPORTANCE(i) A novel aromatic ring-hydroxylating oxygenase named NarA2B2, capable of degrading multiple polycyclic aromatic hydrocarbons and derivatives, was identified from the thermophilic microorganism Hydrogenibacillus sp. N12. (ii) The degradation characteristics of NarA2B2 were characterized by adding one or two atoms of molecular oxygen to the substrate. Unlike the previous study, NarA2B2 catalyzed biphenyl at C-2, 2 or C-3, 4 positions. (iii) Catalytic sites of NarA2B2 were conserved, and key amino acids F216, D219, H222, T223, H227, V236, F243, Y300, H302, W316, F369, and D379 played pivotal roles in catalysis, as confirmed by protein structure prediction, molecular docking, molecular dynamics simulations, and point mutation.
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Affiliation(s)
- Lihua Guo
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xingyu Ouyang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Weiwei Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Yiqun Huang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Xiaoyu Qiu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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3
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Tian J, Boggs DG, Donnan PH, Barroso GT, Garcia AA, Dowling DP, Buss JA, Bridwell-Rabb J. The NADH recycling enzymes TsaC and TsaD regenerate reducing equivalents for Rieske oxygenase chemistry. J Biol Chem 2023; 299:105222. [PMID: 37673337 PMCID: PMC10579966 DOI: 10.1016/j.jbc.2023.105222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 08/22/2023] [Accepted: 08/31/2023] [Indexed: 09/08/2023] Open
Abstract
Many microorganisms use both biological and nonbiological molecules as sources of carbon and energy. This resourcefulness means that some microorganisms have mechanisms to assimilate pollutants found in the environment. One such organism is Comamonas testosteroni, which metabolizes 4-methylbenzenesulfonate and 4-methylbenzoate using the TsaMBCD pathway. TsaM is a Rieske oxygenase, which in concert with the reductase TsaB consumes a molar equivalent of NADH. Following this step, the annotated short-chain dehydrogenase/reductase and aldehyde dehydrogenase enzymes TsaC and TsaD each regenerate a molar equivalent of NADH. This co-occurrence ameliorates the need for stoichiometric addition of reducing equivalents and thus represents an attractive strategy for integration of Rieske oxygenase chemistry into biocatalytic applications. Therefore, in this work, to overcome the lack of information regarding NADH recycling enzymes that function in partnership with Rieske non-heme iron oxygenases (Rieske oxygenases), we solved the X-ray crystal structure of TsaC to a resolution of 2.18 Å. Using this structure, a series of substrate analog and protein variant combination reactions, and differential scanning fluorimetry experiments, we identified active site features involved in binding NAD+ and controlling substrate specificity. Further in vitro enzyme cascade experiments demonstrated the efficient TsaC- and TsaD-mediated regeneration of NADH to support Rieske oxygenase chemistry. Finally, through in-depth bioinformatic analyses, we illustrate the widespread co-occurrence of Rieske oxygenases with TsaC-like enzymes. This work thus demonstrates the utility of these NADH recycling enzymes and identifies a library of short-chain dehydrogenase/reductase enzyme prospects that can be used in Rieske oxygenase pathways for in situ regeneration of NADH.
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Affiliation(s)
- Jiayi Tian
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - David G Boggs
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Patrick H Donnan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Gage T Barroso
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Daniel P Dowling
- Department of Chemistry, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Joshua A Buss
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
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Tian J, Liu J, Knapp M, Donnan PH, Boggs DG, Bridwell-Rabb J. Custom tuning of Rieske oxygenase reactivity. Nat Commun 2023; 14:5858. [PMID: 37730711 PMCID: PMC10511449 DOI: 10.1038/s41467-023-41428-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 08/27/2023] [Indexed: 09/22/2023] Open
Abstract
Rieske oxygenases use a Rieske-type [2Fe-2S] cluster and a mononuclear iron center to initiate a range of chemical transformations. However, few details exist regarding how this catalytic scaffold can be predictively tuned to catalyze divergent reactions. Therefore, in this work, using a combination of structural analyses, as well as substrate and rational protein-based engineering campaigns, we elucidate the architectural trends that govern catalytic outcome in the Rieske monooxygenase TsaM. We identify structural features that permit a substrate to be functionalized by TsaM and pinpoint active-site residues that can be targeted to manipulate reactivity. Exploiting these findings allowed for custom tuning of TsaM reactivity: substrates are identified that support divergent TsaM-catalyzed reactions and variants are created that exclusively catalyze dioxygenation or sequential monooxygenation chemistry. Importantly, we further leverage these trends to tune the reactivity of additional monooxygenase and dioxygenase enzymes, and thereby provide strategies to custom tune Rieske oxygenase reaction outcomes.
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Affiliation(s)
- Jiayi Tian
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Jianxin Liu
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Madison Knapp
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Patrick H Donnan
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - David G Boggs
- Department of Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
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5
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García MM, García de Llasera MP. Electrophoretic characterization of cellular and extracellular proteins from Selenastrum capricornutum cultures degrading benzo(a)pyrene and their identification by UPLC-ESI-TOF mass spectrometry. CHEMOSPHERE 2023:139284. [PMID: 37348613 DOI: 10.1016/j.chemosphere.2023.139284] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 06/13/2023] [Accepted: 06/19/2023] [Indexed: 06/24/2023]
Abstract
Selenastrum capricornutum efficiently degrades benzo(a)pyrene (BaP) but few proteins related to BaP degradation have been identified in this microalgae. So far, it has only been suggested that it could degrade BaP via the monooxygenase and/or dioxygenase pathways. To know more about this fact, in this work, cultures of S. capricornutum incubated with BaP were used to obtain the molecular weights (MWs) of proteins existing in its extra- and cellular extracts by electrophoresis and UPLC-ESI(+)-TOF MS analysis. The results of this proteomic approach indicated that BaP markedly induces the MWs: 6-20, 30, 45, and 65 kDa in cells; 6-20, 30.3, 38-45, and 55 kDa in liquid medium. So, these proteins could be related to BaP biodegradation. An identified protein with monooxygenase activity and rubredoxins (Rds) show to be related to BaP degradation: Rds could participate, together with the monooxygenase in the electron transfer during the formation of monohydroxylated-BaP metabolites. Rds may be also associated with a dioxygenase system that degrades BaP to form dihydrodiol-BaP metabolites. A multi-pass membrane protein was identified too, and it can regulate the transport of molecules like enzymes from inside the cell to the outside environment. At the same time, the presence of a dihydrolipoamide acetyltransferase validated the stress caused by the exposure to BaP. It is noteworthy that these findings provide valuable and original information on the characterization of the proteins of S. capricornutum cultures degrading BaP, whose enzymes have so far not been known. It is important to highlight that the functions of the identified proteins can help in understanding the metabolic and environmental behavior of this microalgae, and the extracts containing the degrading enzymes could be utilized in bioremediation applications.
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Affiliation(s)
- Manuel Méndez García
- Facultad de Química, Departamento de Química Analítica, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D. F., 04510, Mexico
| | - Martha Patricia García de Llasera
- Facultad de Química, Departamento de Química Analítica, Universidad Nacional Autónoma de México, Ciudad Universitaria, México, D. F., 04510, Mexico.
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6
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Lu Y, Wang M, Yu C, Wu Q, Mao Z, Li H, Ren L, Zeng J, Xing P, Zhou LJ, Wan S, Wu QL. Unexpected enrichment of antibiotic resistance genes and organic remediation genes in high-altitude lakes at Eastern Tibetan Plateau. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 874:162554. [PMID: 36870490 DOI: 10.1016/j.scitotenv.2023.162554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/07/2023] [Accepted: 02/25/2023] [Indexed: 06/18/2023]
Abstract
Elevation has a strong effect on aquatic microbiome. However, we know little about the effects of elevation on functional genes, especially antibiotic resistance genes (ARGs) and organic remediation genes (ORGs) in freshwater ecosystems. In this study, we analyzed five classes of functional genes including ARGs, metal resistance genes (MRGs), ORGs, bacteriophages, and virulence genes between two high-altitude lakes (HALs) and two low-altitude lakes (LALs) in Mountain Siguniang at Eastern Tibetan Plateau by means of GeoChip 5.0. No differences (Student's t-test, p > 0.05) of gene richness including ARGs, MRGs, ORGs, bacteriophages, and virulence genes in HALs and LALs were found. The abundance of most ARGs and ORGs was higher in HALs than in LALs. For MRGs, the abundance of macro metal resistance genes of potassium, calcium, and aluminum was higher in HALs than in LALs (Student's t-test, p < 0.05; all Cohen's d > 0.8). The abundance of some heavy metal resistance genes of lead and mercury was lower in HALs than in LALs (Student's t-test, p < 0.05; all Cohen's d < -0.8). The composition of these functional genes in HALs differed significantly from in LALs. The functional gene network in HALs was also more complex than that in LALs. We speculate that enrichment of ARGs and ORGs in HALs is related to different microbial communities, exogenous ARGs, and enriched persistent organic pollutants through long-range atmospheric transport driven by the Indian monsoon. This study highlights the unexpected enrichment of ARGs, MRGs, and ORGs in remote lakes at high elevations.
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Affiliation(s)
- Yiwei Lu
- School of Life Sciences, Institute of Life Science and Green Development, Hebei University, Baoding 071002, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Man Wang
- School of Life Sciences, Institute of Life Science and Green Development, Hebei University, Baoding 071002, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Chunyan Yu
- School of Life Sciences, Institute of Life Science and Green Development, Hebei University, Baoding 071002, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Qiong Wu
- School of Life Sciences, Institute of Life Science and Green Development, Hebei University, Baoding 071002, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Zhendu Mao
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Huabing Li
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Lijuan Ren
- Department of Ecology, Jinan University, Guangzhou 510632, China
| | - Jin Zeng
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Peng Xing
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
| | - Li-Jun Zhou
- State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.
| | - Shiqiang Wan
- School of Life Sciences, Institute of Life Science and Green Development, Hebei University, Baoding 071002, China
| | - Qinglong L Wu
- Center for Evolution and Conservation Biology, Southern Marine Sciences and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China; State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
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7
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Tian J, Garcia AA, Donnan PH, Bridwell-Rabb J. Leveraging a Structural Blueprint to Rationally Engineer the Rieske Oxygenase TsaM. Biochemistry 2023. [PMID: 37188334 DOI: 10.1021/acs.biochem.3c00150] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Rieske nonheme iron oxygenases use two metallocenters, a Rieske-type [2Fe-2S] cluster and a mononuclear iron center, to catalyze oxidation reactions on a broad range of substrates. These enzymes are widely used by microorganisms to degrade environmental pollutants and to build complexity in a myriad of biosynthetic pathways that are industrially interesting. However, despite the value of this chemistry, there is a dearth of understanding regarding the structure-function relationships in this enzyme class, which limits our ability to rationally redesign, optimize, and ultimately exploit the chemistry of these enzymes. Therefore, in this work, by leveraging a combination of available structural information and state-of-the-art protein modeling tools, we show that three "hotspot" regions can be targeted to alter the site selectivity, substrate preference, and substrate scope of the Rieske oxygenase p-toluenesulfonate methyl monooxygenase (TsaM). Through mutation of six to 10 residues distributed between three protein regions, TsaM was engineered to behave as either vanillate monooxygenase (VanA) or dicamba monooxygenase (DdmC). This engineering feat means that TsaM was rationally engineered to catalyze an oxidation reaction at the meta and ortho positions of an aromatic substrate, rather than its favored native para position, and that TsaM was redesigned to perform chemistry on dicamba, a substrate that is not natively accepted by the enzyme. This work thus contributes to unlocking our understanding of structure-function relationships in the Rieske oxygenase enzyme class and expands foundational principles for future engineering of these metalloenzymes.
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Affiliation(s)
- Jiayi Tian
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | | | - Patrick H Donnan
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Jennifer Bridwell-Rabb
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, United States
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8
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Yesankar PJ, Patil A, Kapley A, Qureshi A. Catalytic resilience of multicomponent aromatic ring-hydroxylating dioxygenases in Pseudomonas for degradation of polycyclic aromatic hydrocarbons. World J Microbiol Biotechnol 2023; 39:166. [PMID: 37076735 DOI: 10.1007/s11274-023-03617-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/11/2023] [Indexed: 04/21/2023]
Abstract
Hydrophobic organic compounds, either natural or introduced through anthropogenic activities, pose a serious threat to all spheres of life, including humankind. These hydrophobic compounds are recalcitrant and difficult to degrade by the microbial system; however, microbes have also evolved their metabolic and degradative potential. Pseudomonas species have been reported to have a multipotential role in the biodegradation of aromatic hydrocarbons through aromatic ring-hydroxylating dioxygenases (ARHDs). The structural complexity of different hydrophobic substrates and their chemically inert nature demands the explicit role of evolutionary conserved multicomponent enzyme ARHDs. These enzymes catalyze ring activation and subsequent oxidation by adding two molecular oxygen atoms onto the vicinal carbon of the aromatic nucleus. This critical metabolic step in the aerobic mode of degradation of polycyclic aromatic hydrocarbons (PAHs) catalyzed by ARHDs can also be explored through protein molecular docking studies. Protein data analysis enables an understanding of molecular processes and monitoring complex biodegradation reactions. This review summarizes the molecular characterization of five ARHDs from Pseudomonas species already reported for PAH degradation. Homology modeling for the amino acid sequences encoding the catalytic α-subunit of ARHDs and their docking analyses with PAHs suggested that the enzyme active sites show flexibility around the catalytic pocket for binding of low molecular weight (LMW) and high molecular weight (HMW) PAH substrates (naphthalene, phenanthrene, pyrene, benzo[α]pyrene). The alpha subunit harbours variable catalytic pockets and broader channels, allowing relaxed enzyme specificity toward PAHs. ARHD's ability to accommodate different LMW and HMW PAHs demonstrates its 'plasticity', meeting the catabolic demand of the PAH degraders.
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Affiliation(s)
- Prerna J Yesankar
- Environmental Biotechnology and Genomics Division, CSIR-National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur, 440 020, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India
| | - Ayurshi Patil
- Environmental Biotechnology and Genomics Division, CSIR-National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur, 440 020, India
| | - Atya Kapley
- Environmental Biotechnology and Genomics Division, CSIR-National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur, 440 020, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India
| | - Asifa Qureshi
- Environmental Biotechnology and Genomics Division, CSIR-National Environmental Engineering Research Institute (NEERI), Nehru Marg, Nagpur, 440 020, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002, India.
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9
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Engineering Rieske oxygenase activity one piece at a time. Curr Opin Chem Biol 2023; 72:102227. [PMID: 36410250 PMCID: PMC9939785 DOI: 10.1016/j.cbpa.2022.102227] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/04/2022] [Accepted: 10/11/2022] [Indexed: 11/19/2022]
Abstract
Enzyme engineering plays a central role in the development of biocatalysts for biotechnology, chemical and pharmaceutical manufacturing, and environmental remediation. Rational design of proteins has historically relied on targeting active site residues to confer a protein with desirable catalytic properties. However, additional "hotspots" are also known to exist beyond the active site. Structural elements such as subunit-subunit interactions, entrance tunnels, and flexible loops influence enzyme catalysis and serve as potential "hotspots" for engineering. For the Rieske oxygenases, which use a Rieske cluster and mononuclear iron center to catalyze a challenging set of reactions, these outside of the active site regions are increasingly being shown to drive catalytic outcomes. Therefore, here, we highlight recent work on structurally characterized Rieske oxygenases that implicates architectural pieces inside and outside of the active site as key dictators of catalysis, and we suggest that these features may warrant attention in efforts aimed at Rieske oxygenase engineering.
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10
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Rogers MS, Gordon AM, Rappe TM, Goodpaster JD, Lipscomb JD. Contrasting Mechanisms of Aromatic and Aryl-Methyl Substituent Hydroxylation by the Rieske Monooxygenase Salicylate 5-Hydroxylase. Biochemistry 2023; 62:507-523. [PMID: 36583545 PMCID: PMC9854337 DOI: 10.1021/acs.biochem.2c00610] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The hydroxylase component (S5HH) of salicylate-5-hydroxylase catalyzes C5 ring hydroxylation of salicylate but switches to methyl hydroxylation when a C5 methyl substituent is present. The use of 18O2 reveals that both aromatic and aryl-methyl hydroxylations result from monooxygenase chemistry. The functional unit of S5HH comprises a nonheme Fe(II) site located 12 Å across a subunit boundary from a one-electron reduced Rieske-type iron-sulfur cluster. Past studies determined that substrates bind near the Fe(II), followed by O2 binding to the iron to initiate catalysis. Stopped-flow-single-turnover reactions (STOs) demonstrated that the Rieske cluster transfers an electron to the iron site during catalysis. It is shown here that fluorine ring substituents decrease the rate constant for Rieske electron transfer, implying a prior reaction of an Fe(III)-superoxo intermediate with a substrate. We propose that the iron becomes fully oxidized in the resulting Fe(III)-peroxo-substrate-radical intermediate, allowing Rieske electron transfer to occur. STO using 5-CD3-salicylate-d8 occurs with an inverse kinetic isotope effect (KIE). In contrast, STO of a 1:1 mixture of unlabeled and 5-CD3-salicylate-d8 yields a normal product isotope effect. It is proposed that aromatic and aryl-methyl hydroxylation reactions both begin with the Fe(III)-superoxo reaction with a ring carbon, yielding the inverse KIE due to sp2 → sp3 carbon hybridization. After Rieske electron transfer, the resulting Fe(III)-peroxo-salicylate intermediate can continue to aromatic hydroxylation, whereas the equivalent aryl-methyl intermediate formation must be reversible to allow the substrate exchange necessary to yield a normal product isotope effect. The resulting Fe(III)-(hydro)peroxo intermediate may be reactive or evolve through a high-valent iron intermediate to complete the aryl-methyl hydroxylation.
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Affiliation(s)
- Melanie S. Rogers
- Department of Biochemistry, Molecular Biology, and Biophysics and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Adrian M. Gordon
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Todd M. Rappe
- Minnesota NMR Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jason D. Goodpaster
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology, and Biophysics and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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11
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Identification of New Dioxygenases Able to Recognize Polycyclic Aromatic Hydrocarbons with High Aromaticity. Catalysts 2022. [DOI: 10.3390/catal12030279] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs), products from the incomplete combustion of crude oil, are pollutants present in nature. Ring hydroxylating dioxygenase enzymes are able to catalyze polycyclic aromatic hydrocarbons in the biodegradation process with a high degree of stereo-, regio-, and enantiospecificity. In this work, we present the first approximation of the binding modes of 9 PAHs with high aromaticity in the catalytic sites of biphenyl or naphthalene dioxygenases from four microorganisms usually used in bio-remediation processes: Sphingobium yanoikuyae, Rhodococcus jostii RHA1, Pseudomonas sp. C18, and Paraburkholderia xenovorans. Molecular modeling studies of two biphenyl dioxygenases from Sphingobium yanoikuyae and Paraburkholderia xenovorans showed good binding affinity for PAHs with 2–4 benzene rings (fluoranthene, pyrene, and chrysene), and both enzymes had a similar amount of substrate binding. Molecular docking studies using naphthalene dioxygenase from Pseudomonas sp. C18 showed that the enzyme is able to accommodate PAHs with high aromaticity (benzo(a)pyrene, indeno(1,2,3-cd)pyrene), with good docking scores. This study provides important insight into the utility of naphthalene dioxygenases in the degradation of HAPs with high aromaticity.
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Xue SW, Tian YX, Pan JC, Liu YN, Ma YL. Binding interaction of a ring-hydroxylating dioxygenase with fluoranthene in Pseudomonas aeruginosa DN1. Sci Rep 2021; 11:21317. [PMID: 34716364 PMCID: PMC8556375 DOI: 10.1038/s41598-021-00783-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Accepted: 10/18/2021] [Indexed: 11/11/2022] Open
Abstract
Pseudomonas aeruginosa DN1 can efficiently utilize fluoranthene as its sole carbon source, and the initial reaction in the biodegradation process is catalyzed by a ring-hydroxylating dioxygenase (RHD). To clarify the binding interaction of RHD with fluoranthene in the strain DN1, the genes encoding alpha subunit (RS30940) and beta subunit (RS05115) of RHD were functionally characterized through multi-technique combination such as gene knockout and homology modeling as well as molecular docking analysis. The results showed that the mutants lacking the characteristic alpha subunit and/or beta subunit failed to degrade fluoranthene effectively. Based on the translated protein sequence and Ramachandran plot, 96.5% of the primary amino-acid sequences of the alpha subunit in the modeled structure of the RHD were in the permitted region, 2.3% in the allowed region, but 1.2% in the disallowed area. The catalytic mechanism mediated by key residues was proposed by the simulations of molecular docking, wherein the active site of alpha subunit constituted a triangle structure of the mononuclear iron atom and the two oxygen atoms coupled with the predicted catalytic ternary of His217-His222-Asp372 for the dihydroxylation reaction with fluoranthene. Those amino acid residues adjacent to fluoranthene were nonpolar groups, and the C7-C8 positions on the fluoranthene ring were estimated to be the best oxidation sites. The distance of C7-O and C8-O was 3.77 Å and 3.04 Å respectively, and both of them were parallel. The results of synchronous fluorescence and site-directed mutagenesis confirmed the roles of the predicted residues during catalysis. This binding interaction could enhance our understanding of the catalytic mechanism of RHDs and provide a solid foundation for further enzymatic modification.
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Affiliation(s)
- Shu-Wen Xue
- grid.412262.10000 0004 1761 5538Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi’an, 710069 Shaanxi China ,grid.412262.10000 0004 1761 5538College of Life Science, Northwest University, 229 Taibai North Rd, Xi’an, 710069 Shaanxi China
| | - Yue-Xin Tian
- grid.412262.10000 0004 1761 5538Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi’an, 710069 Shaanxi China ,grid.412262.10000 0004 1761 5538College of Life Science, Northwest University, 229 Taibai North Rd, Xi’an, 710069 Shaanxi China
| | - Jin-Cheng Pan
- grid.412262.10000 0004 1761 5538Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi’an, 710069 Shaanxi China ,grid.412262.10000 0004 1761 5538College of Life Science, Northwest University, 229 Taibai North Rd, Xi’an, 710069 Shaanxi China
| | - Ya-Ni Liu
- grid.412262.10000 0004 1761 5538Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi’an, 710069 Shaanxi China ,grid.412262.10000 0004 1761 5538College of Life Science, Northwest University, 229 Taibai North Rd, Xi’an, 710069 Shaanxi China
| | - Yan-Ling Ma
- grid.412262.10000 0004 1761 5538Shaanxi Provincial Key Laboratory of Biotechnology, Key Laboratory of Resources Biology and Biotechnology in Western China, Ministry of Education, College of Life Science, Northwest University, Xi’an, 710069 Shaanxi China ,grid.412262.10000 0004 1761 5538College of Life Science, Northwest University, 229 Taibai North Rd, Xi’an, 710069 Shaanxi China
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Filatov DA, Kopytov MA, Ovsyannikova VS, Elchaninova EA. Oxidation of a Mixture of Polyaromatic Hydrocarbons by a Mixed Culture of Hydrocarbon-Oxidizing Microorganisms. EURASIAN CHEMICO-TECHNOLOGICAL JOURNAL 2021. [DOI: 10.18321/ectj1034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The possibility of biochemical oxidation of polyaromatic hydrocarbon mixtures (PAHs) by the mixed culture of hydrocarbon-oxidizing microorganisms (HOM) in a liquid medium and soil was investigated. The mixed HOM culture was represented by Pseudomonas stutzeri, Pseudomonas putida, Bacillus cereus, and Arthrobacter globiformis genera. It was shown that during HOM cultivation of the microorganisms under study in the liquid medium their number increases from 0.25·104 to 11·108 CFU/ml, which is accompanied by an increase in their oxygenase activity. All PAHs identified were subjected to oxidation from 11.3 to 100%. The results of experiments on biodegradation of PAHs under natural conditions have shown that for 60 days the total utilization of oil products in soils was on the average 65% of the initial contamination. This suggests the prospects for the use of the mixed HOM culture under study for effective biodegradation of PAHs polluting soil and waste waters.
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Sutherlin KD, Rivard BS, Böttger LH, Liu LV, Rogers MS, Srnec M, Park K, Yoda Y, Kitao S, Kobayashi Y, Saito M, Seto M, Hu M, Zhao J, Lipscomb JD, Solomon EI. NRVS Studies of the Peroxide Shunt Intermediate in a Rieske Dioxygenase and Its Relation to the Native Fe II O 2 Reaction. J Am Chem Soc 2018; 140:5544-5559. [PMID: 29618204 PMCID: PMC5973823 DOI: 10.1021/jacs.8b01822] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The Rieske dioxygenases are a major subclass of mononuclear nonheme iron enzymes that play an important role in bioremediation. Recently, a high-spin FeIII-(hydro)peroxy intermediate (BZDOp) has been trapped in the peroxide shunt reaction of benzoate 1,2-dioxygenase. Defining the structure of this intermediate is essential to understanding the reactivity of these enzymes. Nuclear resonance vibrational spectroscopy (NRVS) is a recently developed synchrotron technique that is ideal for obtaining vibrational, and thus structural, information on Fe sites, as it gives complete information on all vibrational normal modes containing Fe displacement. In this study, we present NRVS data on BZDOp and assign its structure using these data coupled to experimentally calibrated density functional theory calculations. From this NRVS structure, we define the mechanism for the peroxide shunt reaction. The relevance of the peroxide shunt to the native FeII/O2 reaction is evaluated. For the native FeII/O2 reaction, an FeIII-superoxo intermediate is found to react directly with substrate. This process, while uphill thermodynamically, is found to be driven by the highly favorable thermodynamics of proton-coupled electron transfer with an electron provided by the Rieske [2Fe-2S] center at a later step in the reaction. These results offer important insight into the relative reactivities of FeIII-superoxo and FeIII-hydroperoxo species in nonheme Fe biochemistry.
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Affiliation(s)
- Kyle D. Sutherlin
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Brent S. Rivard
- Department of Biochemistry, Molecular Biology, & Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Lars H. Böttger
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Lei V. Liu
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Melanie S. Rogers
- Department of Biochemistry, Molecular Biology, & Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Martin Srnec
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- J. HeyrovskýInstitute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 2155/3, 182 23 Prague 8, Czech Republic
| | - Kiyoung Park
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Department of Chemistry, KAIST, Daejeon 34141, Republic of Korea
| | - Yoshitaka Yoda
- Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan
| | - Shinji Kitao
- Research Reactor Institute, Kyoto University, Osaka 590-0494, Japan
| | | | - Makina Saito
- Research Reactor Institute, Kyoto University, Osaka 590-0494, Japan
| | - Makoto Seto
- Research Reactor Institute, Kyoto University, Osaka 590-0494, Japan
| | - Michael Hu
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Jiyong Zhao
- Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology, & Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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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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16
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Zeng J, Zhu Q, Wu Y, Chen H, Lin X. Characterization of a polycyclic aromatic ring-hydroxylation dioxygenase from Mycobacterium sp. NJS-P. CHEMOSPHERE 2017; 185:67-74. [PMID: 28686888 DOI: 10.1016/j.chemosphere.2017.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 06/01/2017] [Accepted: 07/01/2017] [Indexed: 06/07/2023]
Abstract
Ring-hydroxylating dioxygenases (RHDs) play a critical role in the biodegradation of polycyclic aromatic hydrocarbons (PAHs). In this study, genes pdoAB encoding a dioxygenase capable of oxidizing various PAHs with up to five-ring benzo[a]pyrene were cloned from Mycobacterium sp. NJS-P. The α-subunit of the PdoAB showed 99% and 93% identity to that from Mycobacterium sp. S65 and Mycobacterium sp. py136, respectively. An Escherichia coli expression experiment revealed that the enzyme is able to oxidize anthracene, phenanthrene, pyrene and benzo[a]pyrene, but not to fluoranthene and benzo[a]anthracene. Furthermore, the results of in silico analysis showed that PdoAB has a large substrate-binding pocket satisfying for accommodation of HMW PAHs, and suggested that the binding energy of intermolecular interaction may predict the substrate conversion of RHDs towards HMW PAHs, especially those may have steric constraints on the substrate-binding pocket, such as benzo[a]pyrene and benzo[a]anthracene.
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Affiliation(s)
- Jun Zeng
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing 210008, PR China; Joint Open Laboratory of Soil and the Environment, Hong Kong University and Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Qinghe Zhu
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing 210008, PR China; Joint Open Laboratory of Soil and the Environment, Hong Kong University and Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Yucheng Wu
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing 210008, PR China; Joint Open Laboratory of Soil and the Environment, Hong Kong University and Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China
| | - Hong Chen
- Soil and Environment Analysis Center, Institute of Soil Science, Chinese Academy of Science, PR China
| | - Xiangui Lin
- Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing 210008, PR China; Joint Open Laboratory of Soil and the Environment, Hong Kong University and Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
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17
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The competition between chemistry and biology in assembling iron–sulfur derivatives. Molecular structures and electrochemistry. Part III. {[Fe2S2](Cys)3(X)} (X=Asp, Arg, His) and {[Fe2S2](Cys)2(His)2} proteins. Coord Chem Rev 2016. [DOI: 10.1016/j.ccr.2015.07.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Dihydroxylation of four- and five-ring aromatic hydrocarbons by the naphthalene dioxygenase from Sphingomonas CHY-1. Appl Microbiol Biotechnol 2015; 100:1253-1263. [DOI: 10.1007/s00253-015-7050-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/20/2015] [Accepted: 09/29/2015] [Indexed: 12/23/2022]
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19
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Pleiotropic and epistatic behavior of a ring-hydroxylating oxygenase system in the polycyclic aromatic hydrocarbon metabolic network from Mycobacterium vanbaalenii PYR-1. J Bacteriol 2014; 196:3503-15. [PMID: 25070740 DOI: 10.1128/jb.01945-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Despite the considerable knowledge of bacterial high-molecular-weight (HMW) polycyclic aromatic hydrocarbon (PAH) metabolism, the key enzyme(s) and its pleiotropic and epistatic behavior(s) responsible for low-molecular-weight (LMW) PAHs in HMW PAH-metabolic networks remain poorly understood. In this study, a phenotype-based strategy, coupled with a spray plate method, selected a Mycobacterium vanbaalenii PYR-1 mutant (6G11) that degrades HMW PAHs but not LMW PAHs. Sequence analysis determined that the mutant was defective in pdoA2, encoding an aromatic ring-hydroxylating oxygenase (RHO). A series of metabolic comparisons using high-performance liquid chromatography (HPLC) analysis revealed that the mutant had a lower rate of degradation of fluorene, anthracene, and pyrene. Unlike the wild type, the mutant did not produce a color change in culture media containing fluorene, phenanthrene, and fluoranthene. An Escherichia coli expression experiment confirmed the ability of the Pdo system to oxidize biphenyl, the LMW PAHs naphthalene, phenanthrene, anthracene, and fluorene, and the HMW PAHs pyrene, fluoranthene, and benzo[a]pyrene, with the highest enzymatic activity directed toward three-ring PAHs. Structure analysis and PAH substrate docking simulations of the Pdo substrate-binding pocket rationalized the experimentally observed metabolic versatility on a molecular scale. Using information obtained in this study and from previous work, we constructed an RHO-centric functional map, allowing pleiotropic and epistatic enzymatic explanation of PAH metabolism. Taking the findings together, the Pdo system is an RHO system with the pleiotropic responsibility of LMW PAH-centric hydroxylation, and its epistatic functional contribution is also crucial for the metabolic quality and quantity of the PAH-MN.
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Kim D, Yoo M, Choi KY, Kang BS, Kim E. Characterization and engineering of an o-xylene dioxygenase for biocatalytic applications. BIORESOURCE TECHNOLOGY 2013; 145:123-127. [PMID: 23562567 DOI: 10.1016/j.biortech.2013.03.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 03/03/2013] [Accepted: 03/07/2013] [Indexed: 06/02/2023]
Abstract
Depending on the size and position of the substituent groups on the aromatic ring, the o-xylene dioxygenase from Rhodococcus sp. strain DK17 possesses the unique ability to perform distinct regioselective hydroxylations via differential positioning of substrates within the active site. The substrate-binding pocket of the DK17 o-xylene dioxygenase is large enough to accommodate bicyclics and can be divided into three regions (distal, central, and proximal), and hydrophobic interactions in the distal position are important for substrate binding. Current molecular and functional knowledge contribute insights into how to engineer this enzyme to create tailor-made properties for chemoenzymatic syntheses.
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Affiliation(s)
- Dockyu Kim
- Department of Systems Biology, Yonsei University, Seoul 120-749, Republic of Korea
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21
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In silico bioremediation of polycyclic aromatic hydrocarbon: A frontier in environmental chemistry. J Mol Graph Model 2013; 44:1-8. [DOI: 10.1016/j.jmgm.2013.04.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 04/24/2013] [Accepted: 04/27/2013] [Indexed: 11/23/2022]
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22
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Baboshin MA, Golovleva LA. Aerobic bacterial degradation of polycyclic aromatic hydrocarbons (PAHs) and its kinetic aspects. Microbiology (Reading) 2012. [DOI: 10.1134/s0026261712060021] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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23
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Martin F, Malagnoux L, Violet F, Jakoncic J, Jouanneau Y. Diversity and catalytic potential of PAH-specific ring-hydroxylating dioxygenases from a hydrocarbon-contaminated soil. Appl Microbiol Biotechnol 2012; 97:5125-35. [PMID: 22903320 DOI: 10.1007/s00253-012-4335-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 07/20/2012] [Accepted: 07/21/2012] [Indexed: 10/28/2022]
Abstract
Ring-hydroxylating dioxygenases (RHDs) catalyze the initial oxidation step of a range of aromatic hydrocarbons including polycyclic aromatic hydrocarbons (PAHs). As such, they play a key role in the bacterial degradation of these pollutants in soil. Several polymerase chain reaction (PCR)-based methods have been implemented to assess the diversity of RHDs in soil, allowing limited sequence-based predictions on RHD function. In the present study, we developed a method for the isolation of PAH-specific RHD gene sequences of Gram-negative bacteria, and for analysis of their catalytic function. The genomic DNA of soil PAH degraders was labeled in situ by stable isotope probing, then used to PCR amplify sequences specifying the catalytic domain of RHDs. Sequences obtained fell into five clusters phylogenetically linked to RHDs from either Sphingomonadales or Burkholderiales. However, two clusters comprised sequences distantly related to known RHDs. Some of these sequences were cloned in-frame in place of the corresponding region of the phnAIa gene from Sphingomonas CHY-1 to generate hybrid genes, which were expressed in Escherichia. coli as chimerical enzyme complexes. Some of the RHD chimeras were found to be competent in the oxidation of two- and three-ring PAHs, but other appeared unstable. Our data are interpreted in structural terms based on 3D modeling of the catalytic subunit of hybrid RHDs. The strategy described herein might be useful for exploring the catalytic potential of the soil metagenome and recruit RHDs with new activities from uncultured soil bacteria.
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Affiliation(s)
- Florence Martin
- Laboratoire de Chimie et Biologie des Métaux, CEA, DSV, 38054 Grenoble Cedex 9, France
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Librando V, Pappalardo M. Engineered enzyme interactions with polycyclic aromatic hydrocarbons: A theoretical approach. J Mol Graph Model 2012; 36:30-5. [DOI: 10.1016/j.jmgm.2012.02.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 02/20/2012] [Accepted: 02/28/2012] [Indexed: 11/26/2022]
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25
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Daughtry KD, Xiao Y, Stoner-Ma D, Cho E, Orville AM, Liu P, Allen KN. Quaternary ammonium oxidative demethylation: X-ray crystallographic, resonance Raman, and UV-visible spectroscopic analysis of a Rieske-type demethylase. J Am Chem Soc 2012; 134:2823-34. [PMID: 22224443 DOI: 10.1021/ja2111898] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Herein, the structure resulting from in situ turnover in a chemically challenging quaternary ammonium oxidative demethylation reaction was captured via crystallographic analysis and analyzed via single-crystal spectroscopy. Crystal structures were determined for the Rieske-type monooxygenase, stachydrine demethylase, in the unliganded state (at 1.6 Å resolution) and in the product complex (at 2.2 Å resolution). The ligand complex was obtained from enzyme aerobically cocrystallized with the substrate stachydrine (N,N-dimethylproline). The ligand electron density in the complex was interpreted as proline, generated within the active site at 100 K by the absorption of X-ray photon energy and two consecutive demethylation cycles. The oxidation state of the Rieske iron-sulfur cluster was characterized by UV-visible spectroscopy throughout X-ray data collection in conjunction with resonance Raman spectra collected before and after diffraction data. Shifts in the absorption band wavelength and intensity as a function of absorbed X-ray dose demonstrated that the Rieske center was reduced by solvated electrons generated by X-ray photons; the kinetics of the reduction process differed dramatically for the liganded complex compared to unliganded demethylase, which may correspond to the observed turnover in the crystal.
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Affiliation(s)
- Kelly D Daughtry
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02218, USA
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26
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Mohammadi M, Viger JF, Kumar P, Barriault D, Bolin JT, Sylvestre M. Retuning Rieske-type oxygenases to expand substrate range. J Biol Chem 2011; 286:27612-21. [PMID: 21653696 DOI: 10.1074/jbc.m111.255174] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Rieske-type oxygenases are promising biocatalysts for the destruction of persistent pollutants or for the synthesis of fine chemicals. In this work, we explored pathways through which Rieske-type oxygenases evolve to expand their substrate range. BphAE(p4), a variant biphenyl dioxygenase generated from Burkholderia xenovorans LB400 BphAE(LB400) by the double substitution T335A/F336M, and BphAE(RR41), obtained by changing Asn(338), Ile(341), and Leu(409) of BphAE(p4) to Gln(338), Val(341), and Phe(409), metabolize dibenzofuran two and three times faster than BphAE(LB400), respectively. Steady-state kinetic measurements of single- and multiple-substitution mutants of BphAE(LB400) showed that the single T335A and the double N338Q/L409F substitutions contribute significantly to enhanced catalytic activity toward dibenzofuran. Analysis of crystal structures showed that the T335A substitution relieves constraints on a segment lining the catalytic cavity, allowing a significant displacement in response to dibenzofuran binding. The combined N338Q/L409F substitutions alter substrate-induced conformational changes of protein groups involved in subunit assembly and in the chemical steps of the reaction. This suggests a responsive induced fit mechanism that retunes the alignment of protein atoms involved in the chemical steps of the reaction. These enzymes can thus expand their substrate range through mutations that alter the constraints or plasticity of the catalytic cavity to accommodate new substrates or that alter the induced fit mechanism required to achieve proper alignment of reaction-critical atoms or groups.
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Affiliation(s)
- Mahmood Mohammadi
- Institut National de la Recherche Scientifique-Institut Armand-Frappier, Laval, Quebec H7V 1B7, Canada
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27
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Computational study on the interaction of a ring-hydroxylating dioxygenase from Sphingomonas CHY-1 with PAHs. J Mol Graph Model 2011; 29:915-9. [DOI: 10.1016/j.jmgm.2011.03.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 01/19/2011] [Accepted: 03/02/2011] [Indexed: 11/20/2022]
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Yoo M, Kim D, Zylstra GJ, Kang BS, Kim E. Biphenyl hydroxylation enhanced by an engineered o-xylene dioxygenase from Rhodococcus sp. strain DK17. Res Microbiol 2011; 162:724-8. [PMID: 21575716 DOI: 10.1016/j.resmic.2011.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2010] [Accepted: 04/04/2011] [Indexed: 10/18/2022]
Abstract
Hydroxylation of the non-growth substrate biphenyl by recombinant o-xylene dioxygenases from Rhodococcus sp. strain DK17 was studied through bioconversion experiments. The metabolites from the biphenyl hydroxylation by each enzyme were identified and quantified by gas chromatography-mass spectrometry. The L266F mutant enzyme produced much more 2-hydroxybiphenyl (2.43 vs. 0.1 μg/L) and 3-hydroxybiphenyl (1.97 vs. 0.03 μg/L) than the wild-type. Site-directed mutagenesis combined with structural and functional analyses indicated that hydrophobic interactions and shielding effects against water are important factors in the hydroxylation of biphenyl by the o-xylene dioxygenase. The residue at position 266 plays a key role in coordinating the reaction.
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Affiliation(s)
- Miyoun Yoo
- Department of Biology, Yonsei University, Seoul 120-749, South Korea
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Bacteria-mediated PAH degradation in soil and sediment. Appl Microbiol Biotechnol 2011; 89:1357-71. [PMID: 21210104 DOI: 10.1007/s00253-010-3072-7] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 12/09/2010] [Accepted: 12/09/2010] [Indexed: 10/18/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the natural environment and easily accumulate in soil and sediment due to their low solubility and high hydrophobicity, rendering them less available for biological degradation. However, microbial degradation is a promising mechanism which is responsible for the ecological recovery of PAH-contaminated soil and sediment for removing these recalcitrant compounds compared with chemical degradation of PAHs. The goal of this review is to provide an outline of the current knowledge of biodegradation of PAHs in related aspects. Over 102 publications related to PAH biodegradation in soil and sediment are compiled, discussed, and analyzed. This review aims to discuss PAH degradation under various redox potential conditions, the factors affecting the biodegradation rates, degrading bacteria, the relevant genes in molecular monitoring methods, and some recent-year bioremediation field studies. The comprehensive understanding of the bioremediation kinetics and molecular means will be helpful for optimizing and monitoring the process, and overcoming its limitations in practical projects.
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Crystal structure of γ-hexachlorocyclohexane Dehydrochlorinase LinA from Sphingobium japonicum UT26. J Mol Biol 2010; 403:260-9. [PMID: 20813114 DOI: 10.1016/j.jmb.2010.08.043] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 08/19/2010] [Accepted: 08/23/2010] [Indexed: 10/19/2022]
Abstract
LinA from Sphingobium japonicum UT26 catalyzes two steps of dehydrochlorination from γ hexachlorocyclohexane (HCH) to 1,3,4,6-tetrachloro-1,4-cyclohexadiene via γ-pentachlorocyclohexene. We determined the crystal structure of LinA at 2.25 Å by single anomalous dispersion. LinA exists as a homotrimer, and each protomer forms a cone-shaped α+β barrel fold. The C-terminal region of LinA is extended to the neighboring subunit, unlike that of scytalone dehydratase from Magnaporthe grisea, which is one of the most structurally similar proteins identified by the DALI server. The structure we obtained in this study is in open form, in which γ-HCH can enter the active site. There is a hydrophobic cavity inside the barrel fold, and the active site is largely surrounded by the side chains of K20, L21, V24, D25, W42, L64, F68, C71, H73, V94, L96, I109, F113, and R129. H73 was considered to function as a base that abstracts the proton of γ-HCH through its interaction with D25. Docking simulations with γ-HCH and γ-pentachlorocyclohexene suggest that 11 residues (K20, I44, L64, V94, L96, I109, A111, F113, A131, C132, and T133) are involved in the binding of these compounds and support the degradation mechanism.
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31
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Substrate specificity and structural characteristics of the novel Rieske nonheme iron aromatic ring-hydroxylating oxygenases NidAB and NidA3B3 from Mycobacterium vanbaalenii PYR-1. mBio 2010; 1. [PMID: 20714442 PMCID: PMC2921158 DOI: 10.1128/mbio.00135-10] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Accepted: 05/05/2010] [Indexed: 11/20/2022] Open
Abstract
The Rieske nonheme iron aromatic ring-hydroxylating oxygenases (RHOs) NidAB and NidA3B3 from Mycobacterium vanbaalenii PYR-1 have been implicated in the initial oxidation of high-molecular-weight (HMW) polycyclic aromatic hydrocarbons (PAHs), forming cis-dihydrodiols. To clarify how these two RHOs are functionally different with respect to the degradation of HMW PAHs, we investigated their substrate specificities to 13 representative aromatic substrates (toluene, m-xylene, phthalate, biphenyl, naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, benz[a]anthracene, benzo[a]pyrene, carbazole, and dibenzothiophene) by enzyme reconstitution studies of Escherichia coli. Both Nid systems were identified to be compatible with type V electron transport chain (ETC) components, consisting of a [3Fe-4S]-type ferredoxin and a glutathione reductase (GR)-type reductase. Metabolite profiles indicated that the Nid systems oxidize a wide range of aromatic hydrocarbon compounds, producing various isomeric dihydrodiol and phenolic compounds. NidAB and NidA3B3 showed the highest conversion rates for pyrene and fluoranthene, respectively, with high product regiospecificity, whereas other aromatic substrates were converted at relatively low regiospecificity. Structural characteristics of the active sites of the Nid systems were investigated and compared to those of other RHOs. The NidAB and NidA3B3 systems showed the largest substrate-binding pockets in the active sites, which satisfies spatial requirements for accepting HMW PAHs. Spatially conserved aromatic amino acids, Phe-Phe-Phe, in the substrate-binding pockets of the Nid systems appeared to play an important role in keeping aromatic substrates within the reactive distance from the iron atom, which allows each oxygen to attack the neighboring carbons.
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Kanaly RA, Harayama S. Advances in the field of high-molecular-weight polycyclic aromatic hydrocarbon biodegradation by bacteria. Microb Biotechnol 2010; 3:136-64. [PMID: 21255317 PMCID: PMC3836582 DOI: 10.1111/j.1751-7915.2009.00130.x] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 05/22/2009] [Accepted: 05/26/2009] [Indexed: 11/26/2022] Open
Abstract
Interest in understanding prokaryotic biotransformation of high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs) has continued to grow and the scientific literature shows that studies in this field are originating from research groups from many different locations throughout the world. In the last 10 years, research in regard to HMW PAH biodegradation by bacteria has been further advanced through the documentation of new isolates that represent diverse bacterial types that have been isolated from different environments and that possess different metabolic capabilities. This has occurred in addition to the continuation of in-depth comprehensive characterizations of previously isolated organisms, such as Mycobacterium vanbaalenii PYR-1. New metabolites derived from prokaryotic biodegradation of four- and five-ring PAHs have been characterized, our knowledge of the enzymes involved in these transformations has been advanced and HMW PAH biodegradation pathways have been further developed, expanded upon and refined. At the same time, investigation of prokaryotic consortia has furthered our understanding of the capabilities of microorganisms functioning as communities during HMW PAH biodegradation.
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Affiliation(s)
- Robert A Kanaly
- Department of Genome Systems, Faculty of Bionanoscience, Yokohama City University, 22-2 Seto, Kanazawa-ku, Kanagawa-ken, Yokohama 236-0027, Japan.
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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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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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Tarasev M, Kaddis CS, Yin S, Loo JA, Burgner J, Ballou DP. Similar enzymes, different structures: phthalate dioxygenase is an alpha3alpha3 stacked hexamer, not an alpha3beta3 trimer like "normal" Rieske oxygenases. Arch Biochem Biophys 2007; 466:31-9. [PMID: 17764654 PMCID: PMC2084370 DOI: 10.1016/j.abb.2007.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 07/05/2007] [Accepted: 07/06/2007] [Indexed: 11/24/2022]
Abstract
Phthalate dioxygenase (PDO) is a member of a class of bacterial oxygenases that contain both Rieske [2Fe-2S] and Fe(II) mononuclear centers. Recent crystal structures of several Rieske dioxygenases showed that they exist as alpha(3)beta(3) multimers with subunits arranged head-to-tail in alpha and beta stacked planar rings. The structure of PDO, which consists of only alpha-subunits, remains to be solved. Although similar to other Rieske dioxygenases in many aspects, PDO was shown to differ in the mechanism of catalysis. Gel filtration and analytical centrifugation experiments, supplemented with mass spectrometric analysis (both ESI-MS and ESI-GEMMA), in this work showed a hexameric arrangement of subunits in the PDO multimer. Our proposed model for the subunit arrangement in PDO postulates two alpha(3) planar rings one on top the other, similar to the alpha(3)beta(3) arrangement in other Rieske dioxygenases. Unlike other Rieske dioxygenases, this arrangement brings two Rieske and two mononuclear centers, all on separate subunits, into proximity, allowing their cooperation for catalysis. Potential reasons necessitating this unusual structural arrangement are discussed.
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Affiliation(s)
- Michael Tarasev
- Department of Biological Chemistry, University of Michigan, 1301 Catherine Street, Ann Arbor, MI 48109-0606, USA
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Jakoncic J, Jouanneau Y, Meyer C, Stojanoff V. The crystal structure of the ring-hydroxylating dioxygenase from Sphingomonas CHY-1. FEBS J 2007; 274:2470-81. [PMID: 17451434 DOI: 10.1111/j.1742-4658.2007.05783.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ring-hydroxylating dioxygenase (RHD) from Sphingomonas CHY-1 is remarkable due to its ability to initiate the oxidation of a wide range of polycyclic aromatic hydrocarbons (PAHs), including PAHs containing four- and five-fused rings, known pollutants for their toxic nature. Although the terminal oxygenase from CHY-1 exhibits limited sequence similarity with well characterized RHDs from the naphthalene dioxygenase family, the crystal structure determined to 1.85 A by molecular replacement revealed the enzyme to share the same global alpha(3)beta(3) structural pattern. The catalytic domain distinguishes itself from other bacterial non-heme Rieske iron oxygenases by a substantially larger hydrophobic substrate binding pocket, the largest ever reported for this type of enzyme. While residues in the proximal region close to the mononuclear iron atom are conserved, the central region of the catalytic pocket is shaped mainly by the side chains of three amino acids, Phe350, Phe404 and Leu356, which contribute to the rather uniform trapezoidal shape of the pocket. Two flexible loops, LI and LII, exposed to the solvent seem to control the substrate access to the catalytic pocket and control the pocket length. Compared with other naphthalene dioxygenases residues Leu223 and Leu226, on loop LI, are moved towards the solvent, thus elongating the catalytic pocket by at least 2 A. An 11 A long water channel extends from the interface between the alpha and beta subunits to the catalytic site. The comparison of these structures with other known oxygenases suggests that the broad substrate specificity presented by the CHY-1 oxygenase is primarily due to the large size and particular topology of its catalytic pocket and provided the basis for the study of its reaction mechanism.
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Affiliation(s)
- Jean Jakoncic
- Brookhaven National Laboratory, National Synchrotron Light Source, Upton, NY 11973, USA
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