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Hu H, Xu Z, Zhang Z, Song P, Stull F, Xu P, Tang H. Rational design of a flavoenzyme for aerobic nicotine catabolism. mBio 2024:e0205024. [PMID: 39191403 DOI: 10.1128/mbio.02050-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Accepted: 07/23/2024] [Indexed: 08/29/2024] Open
Abstract
Enzymatic therapy with nicotine-degrading enzyme is a new strategy in treating nicotine addiction, which can reduce nicotine concentrations and weaken withdrawal in the rat model. However, when O2 is used as the electron acceptor, no satisfactory performance has been achieved with one of the most commonly studied and efficient nicotine-catabolizing enzymes, NicA2. To obtain more efficient nicotine-degrading enzyme, we rationally designed and engineered a flavoenzyme Pnao, which shares high structural similarity with NicA2 (RMSD = 1.143 Å) and efficiently catalyze pseudooxynicotine into 3-succinoyl-semialdehyde pyridine using O2. Through amino acid alterations with NicA2, five Pnao mutants were generated, which can degrade nicotine in Tris-HCl buffer and retain catabolic activity on its natural substrate. Nicotine-1'-N-oxide was identified as one of the reaction products. Four of the derivative mutants showed activity in rat serum and Trp220 and Asn224 were found critical for enzyme specificity. Our findings offer a novel avenue for research into aerobic nicotine catabolism and provide a promising method of generating additional nicotine-catalytic enzymes. IMPORTANCE Nicotine, the main active substance in tobacco, results in cigarette addiction and various diseases. There have been some attempts at using nicotine oxidoreductase, NicA2, as a therapeutic for nicotine cessation. However, it uses cytochrome c as it is electron acceptor, which is impractical for therapeutic use compared with using O2 as an oxidant. Thus, amino acid alteration was performed on Pnao using NicA2 as model. Five of the mutants generated degraded nicotine at a rate similar to NicA2, and one of the catabolic compounds was identified as nicotine-1'-N-oxide. Our research highlights a new direction in developing enzymes that efficiently catabolize nicotine without co-enzymes and suggests that structure-similar human original MAOA (or B) may assist with nicotine cessation after being engineered.
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Affiliation(s)
- Haiyang Hu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhaoyong Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Zhiyao Zhang
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA
| | - Peizhi Song
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Frederick Stull
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China
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Hu H, Xu Z, Zhang Z, Song P, Stull F, Xu P, Tang H. Rational Design of a Flavoenzyme for Aerobic Nicotine Catabolism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.11.603087. [PMID: 39026806 PMCID: PMC11257531 DOI: 10.1101/2024.07.11.603087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Enzymatic therapy with nicotine-degrading enzyme is a new strategy in treating nicotine addiction, which can reduce nicotine concentrations and weaken withdrawal in the rat model. However, when O2 is used as the electron acceptor, no satisfactory performance has been achieved with one of the most commonly studied and efficient nicotine-catabolizing enzymes, NicA2. To obtain more efficient nicotine-degrading enzyme, we rationally designed and engineered a flavoenzyme Pnao, which shares high structural similarity with NicA2 (RMSD = 1.143 Å) and efficiently catalyze pseudooxynicotine into 3-succinoyl-semialdehyde pyridine using O2. Through amino acid alterations with NicA2, five Pnao mutants were generated, which can degrade nicotine in Tris-HCl buffer and retained catabolic activity on its natural substrate. Nicotine-1'-N-oxide was identified as one of the reaction products. Four of the derivative mutants showed activity in rat serum and Trp220 and Asn224 were found critical for enzyme specificity. Our findings offer a novel avenue for research into aerobic nicotine catabolism and provides a promising method of generating additional nicotine-catalytic enzymes.
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Affiliation(s)
- Haiyang Hu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Zhaoyong Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Zhiyao Zhang
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | - Peizhi Song
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Frederick Stull
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism, Joint International Research Laboratory of Metabolic and Developmental Sciences, and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
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Choudhary V, Wu K, Zhang Z, Dulchavsky M, Barkman T, Bardwell JCA, Stull F. The enzyme pseudooxynicotine amine oxidase from Pseudomonas putida S16 is not an oxidase, but a dehydrogenase. J Biol Chem 2022; 298:102251. [PMID: 35835223 PMCID: PMC9396064 DOI: 10.1016/j.jbc.2022.102251] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 11/16/2022] Open
Abstract
The soil-dwelling bacterium Pseudomonas putida S16 can survive on nicotine as its sole carbon and nitrogen source. The enzymes nicotine oxidoreductase (NicA2) and pseudooxynicotine amine oxidase (Pnao), both members of the flavin containing amine oxidase family, catalyze the first two steps in the nicotine catabolism pathway. Our laboratory has previously shown that, contrary to other members of its enzyme family, NicA2 is actually a dehydrogenase that uses a cytochrome c protein (CycN) as its electron acceptor. The natural electron acceptor for Pnao is unknown; however, within the P. putida S16 genome, pnao forms an operon with cycN and nicA2, leading us to hypothesize that Pnao may also be a dehydrogenase that uses CycN as its electron acceptor. Here we characterized the kinetic properties of Pnao and show that Pnao is poorly oxidized by O2, but can be rapidly oxidized by CycN, indicating that Pnao indeed acts as a dehydrogenase that uses CycN as its oxidant. Comparing steady-state kinetics with transient kinetic experiments revealed that product release primarily limits turnover by Pnao. We also resolved the crystal structure of Pnao at 2.60 Å, which shows that Pnao has a similar structural fold as NicA2. Furthermore, rigid-body docking of the structure of CycN with Pnao and NicA2 identified a potential conserved binding site for CycN on these two enzymes. Taken together, our results demonstrate that although Pnao and NicA2 show a high degree of similarity to flavin containing amine oxidases that use dioxygen directly, both enzymes are actually dehydrogenases.
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Affiliation(s)
- Vishakha Choudhary
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA
| | - Kevin Wu
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, USA; Department of Biophysics, University of Michigan, Ann Arbor, Michigan, USA
| | - Zhiyao Zhang
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA
| | - Mark Dulchavsky
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, USA; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan, USA
| | - Todd Barkman
- Department of Biological Sciences, Western Michigan University, Kalamazoo, Michigan, USA
| | - James C A Bardwell
- Howard Hughes Medical Institute, University of Michigan, Ann Arbor, Michigan, USA; Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Frederick Stull
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan, USA.
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Bovet L, Campanoni P, Lu J, Hilfiker A, Kleinhans S, Laparra H, Schwaar J, Lewis RS, Matsuba Y, Ma H, Dewey RE, Goepfert S. CLCNt2 Mediates Nitrate Content in Tobacco Leaf, Impacting the Production of Tobacco-Specific Nitrosamines in Cured Leaves. FRONTIERS IN PLANT SCIENCE 2022; 13:741078. [PMID: 35251070 PMCID: PMC8888935 DOI: 10.3389/fpls.2022.741078] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 01/18/2022] [Indexed: 06/14/2023]
Abstract
Nitrate accumulation in tobacco (Nicotiana tabacum L.) leaf, particularly in the burley (BU) type, is a reservoir for the generation of nitrosating agents responsible for the formation of tobacco-specific nitrosamines (TSNAs). TSNAs are mainly produced via the nitrosation of alkaloids occurring during the curing of tobacco leaves. Additional formation of TSNAs may also occur during tobacco storage, leaf processing and in some circumstances via pyrosynthesis during combustion. Two TSNA species, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN) are found in the tobacco products and have been documented to be animal carcinogens. A previous study showed that decreasing the accumulation of nitrate in tobacco leaf via the overexpression of a deregulated form of nitrate reductase is efficient to reduce the production of TSNAs. We pursue in finding another molecular genetic target to lower nitrate in BU tobacco. Suppressing expression or knocking-out CLCNt2 has a direct impact on leaf nitrate and TSNA reduction in cured leaves without altering biomass. This study provides now a straight path toward the development of new commercial tobacco varieties with reduced TSNA levels by breeding of variants deficient in active CLCNt2 copies.
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Affiliation(s)
- Lucien Bovet
- PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
| | | | - Jian Lu
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, United States
| | - Aurore Hilfiker
- PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
| | | | - Hélène Laparra
- PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
| | - Joanne Schwaar
- PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
| | - Ramsey S. Lewis
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, United States
| | - Yuki Matsuba
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, United States
| | - Hong Ma
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, United States
| | - Ralph E. Dewey
- Department of Crop and Soil Sciences, North Carolina State University, Raleigh, NC, United States
| | - Simon Goepfert
- PMI R&D, Philip Morris Products S.A., Neuchatel, Switzerland
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Li J, Yi F, Chen G, Pan F, Yang Y, Shu M, Chen Z, Zhang Z, Mei X, Zhong W. Function Enhancement of a Metabolic Module via Endogenous Promoter Replacement for Pseudomonas sp. JY-Q to Degrade Nicotine in Tobacco Waste Treatment. Appl Biochem Biotechnol 2021; 193:2793-2805. [PMID: 34061306 DOI: 10.1007/s12010-021-03566-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Accepted: 04/08/2021] [Indexed: 12/17/2022]
Abstract
Nicotine-degrading Pseudomonas sp. JY-Q is a preferred strain utilized in reconstituted tobacco process for tobacco waste treatment. However, its efficiency of nicotine metabolism still requires to be improved via genomic technology such as promoter engineering based on genomic information. Concerning upstream module of nicotine metabolic pathway, we found that two homologous genes of nicotine dehydrogenase (nicA2 and nox) coexisted in strain JY-Q. However, the transcriptional amount of nox was 20-fold higher than that of nicA2. Thus, the nicA2 expression required improvement. Combinatorial displacement was accomplished for two predicted endogenous promoters, named as PnicA2 and Pnox for nicA2 and nox, respectively. The mutant with Pnox as the promoters for both nicA2 and nox exhibited the best nicotine metabolic capacity which increased by 66% compared to the wild type. These results suggested that endogenous promoter replacement is also feasible for function improvement of metabolic modules and strain enhancement of biodegradation capacity to meet real environment demand.
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Affiliation(s)
- Jun Li
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Fengmei Yi
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Guoqing Chen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Fanda Pan
- Technology Center, China Tobacco Zhejiang Industrial Co., Ltd., Hangzhou, 310009, China
| | - Yang Yang
- Technology Center, China Tobacco Zhejiang Industrial Co., Ltd., Hangzhou, 310009, China.
| | - Ming Shu
- Technology Center, China Tobacco Zhejiang Industrial Co., Ltd., Hangzhou, 310009, China
| | - Zeyu Chen
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Zeling Zhang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Xiaotong Mei
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China
| | - Weihong Zhong
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310032, China.
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Rid Enhances the 6-Hydroxypseudooxynicotine Dehydrogenase Reaction in Nicotine Degradation by Agrobacterium tumefaciens S33. Appl Environ Microbiol 2021; 87:AEM.02769-20. [PMID: 33514517 DOI: 10.1128/aem.02769-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/17/2021] [Indexed: 02/03/2023] Open
Abstract
Agrobacterium tumefaciens S33 degrades nicotine through a hybrid of the pyridine and pyrrolidine pathways. The oxidation of 6-hydroxypseudooxynicotine to 6-hydroxy-3-succinoyl-semialdehyde-pyridine by 6-hydroxypseudooxynicotine dehydrogenase (Pno) is an important step in the breakdown of the N-heterocycle in this pathway. Although Pno has been characterized, the reaction is not fully understood; what is known is that it starts at a high speed followed by a rapid drop in the reaction rate, leading to the formation of a very small amount of product. In this study, we speculated that an unstable imine intermediate that is toxic with regard to the metabolism is produced in the reaction. We found that a Rid protein (designated Rid-NC) encoded by a gene in the nicotine-degrading gene cluster enhanced the reaction. Rid is a widely distributed family of small proteins with various functions, and some subfamilies have deaminase activity to eliminate the toxicity of the reactive intermediate, imine. Biochemical analyses showed that Rid-NC relieved the toxicity of the presumed imine intermediate produced in the Pno reaction and that, in the presence of Rid-NC, Pno maintained a high level of activity and the amount of the reaction product was increase by at least 5-fold. Disruption of the rid-NC gene led to slower growth of strain S33 on nicotine. The mechanism of Rid-NC-mediated detoxification of the imine intermediate was discussed. A phylogenetic analysis indicated that Rid-NC belongs to the rarely studied Rid6 subfamily. These results further our understanding of the biochemical mechanism of nicotine degradation and provide new insights into the function of the Rid6 subfamily proteins.IMPORTANCE Rid is a family of proteins that participate in metabolite damage repair and is widely distributed in different organisms. In this study, we found that Rid-NC, which belongs to the Rid6 subfamily, promoted the 6-hydroxypseudooxynicotine dehydrogenase (Pno) reaction in the hybrid of the pyridine and pyrrolidine pathways for nicotine degradation by Agrobacterium tumefaciens S33. Rid-NC hydrolyzed the presumed reactive imine intermediate produced in the reaction to remove its toxicity on Pno. The finding furthers our understanding of the metabolic process of the toxic N-heterocyclic aromatic compounds in microorganisms. This study demonstrated that the Rid family of proteins also functions in the metabolism of N-heterocyclic aromatic alkaloids, in addition to the amino acid metabolism, and that Rid6-subfamily proteins also have deaminase activity, similar to the RidA subfamily. The ability of reactive imines to damage a non-pyridoxal-5'-phosphate-dependent enzyme was reported. This study provides new insights into the function of the Rid family of proteins.
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Tararina MA, Dam KK, Dhingra M, Janda KD, Palfey BA, Allen KN. Fast Kinetics Reveals Rate-Limiting Oxidation and the Role of the Aromatic Cage in the Mechanism of the Nicotine-Degrading Enzyme NicA2. Biochemistry 2021; 60:259-273. [PMID: 33464876 DOI: 10.1021/acs.biochem.0c00855] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In Pseudomonas putida, the flavoprotein nicotine oxidoreductase (NicA2) catalyzes the oxidation of (S)-nicotine to N-methyl-myosmine, which is nonenzymatically hydrolyzed to pseudooxynicotine. Structural analysis reveals a monoamine oxidase (MAO)-like fold with a conserved FAD-binding domain and variable substrate-binding domain. The flavoenzyme has a unique variation of the classic aromatic cage with flanking residue pair W427/N462. Previous mechanistic studies using O2 as the oxidizing substrate show that NicA2 has a low apparent Km of 114 nM for (S)-nicotine with a very low apparent turnover number (kcat of 0.006 s-1). Herein, the mechanism of NicA2 was analyzed by transient kinetics. Single-site variants of W427 and N462 were used to probe the roles of these residues. Although several variants had moderately higher oxidase activity (7-12-fold), their reductive half-reactions using (S)-nicotine were generally significantly slower than that of wild-type NicA2. Notably, the reductive half-reaction of wild-type NicA2 is 5 orders of magnitude faster than the oxidative half-reaction with an apparent pseudo-first-order rate constant for the reaction of oxygen similar to kcat. X-ray crystal structures of the N462V and N462Y/W427Y variants complexed with (S)-nicotine (at 2.7 and 2.3 Å resolution, respectively) revealed no significant active-site rearrangements. A second substrate-binding site was identified in N462Y/W427Y, consistent with observed substrate inhibition. Together, these findings elucidate the mechanism of a flavoenzyme that preferentially oxidizes tertiary amines with an efficient reductive half-reaction and a very slow oxidative half-reaction when O2 is the oxidizing substrate, suggesting that the true oxidizing agent is unknown.
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Affiliation(s)
- Margarita A Tararina
- Program in Biomolecular Pharmacology, Boston University School of Medicine, 72 East Concord Street, Boston, Massachusetts 02118, United States
| | - Katie K Dam
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | - Manaswni Dhingra
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
| | | | - Bruce A Palfey
- Department of Biological Chemistry, University of Michigan, 5220E MSRB III 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, United States
| | - Karen N Allen
- Program in Biomolecular Pharmacology, Boston University School of Medicine, 72 East Concord Street, Boston, Massachusetts 02118, United States.,Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
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Abstract
We report the entire process underlying the NicR2 regulatory mechanism from association between free NicR2 and two promoters to dissociation of the NicR2-promoter complex. NicR2 can bind to another promoter, Pspm, which controls expression of nicotine-degrading genes that are not controlled by the Phsp promoter. We identified specific nucleotides of the Pspm promoter responsible for NicR2 binding. HSP was further demonstrated as an antagonist, which prevents the binding of NicR2 to the Pspm and Phsp promoters, by locking NicR2 in the derepression conformation. The competition between NicR2 and RNA polymerase is essential to initiate transcription of nicotine-degrading genes. This study extends our understanding of molecular mechanisms in biodegradation of environmental pollutants and toxicants. Nicotine, a toxic and addictive alkaloid from tobacco, is an environmental pollutant in areas near cigarette production facilities. Over the last decade, our group has studied, in depth, the pyrrolidine pathway of nicotine degradation in Pseudomonas putida S16. However, little is known regarding whole mechanism(s) regulating transcription of the nicotine degradation pathway gene cluster. In the present study, we comprehensively elucidate an overall view of the NicR2-mediated two-step mechanism regulating 3-succinoyl-pyridine (SP) biotransformation, which involves the association of free NicR2 with two promoters and the dissociation of NicR2 from the NicR2-promoter complex. NicR2 can bind to another promoter, Pspm, and regulate expression of the nicotine-degrading genes in the middle of nic2 gene cluster, which are not controlled by the previously reported Phsp promoter. We identified the function of the inverted repeat bases on the two promoters responsible for NicR2 binding and found out that the –35/–10 motif for RNA polymerase is overlapped by the NicR2 binding site. We clarify the exact role of 6-hydroxy-3-succinoyl-pyridine (HSP), which acts as an antagonist and may prevent binding of free NicR2 to the promoters but cannot release NicR2 from the promoters. Finally, a regulatory model is proposed, which consists of three parts: the interaction between NicR2 and two promoters (Pspm and Phsp), the interaction between NicR2 and two effectors (HSP and SP), and the interaction between NicR2 and RNA polymerase.
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6-Hydroxypseudooxynicotine Dehydrogenase Delivers Electrons to Electron Transfer Flavoprotein during Nicotine Degradation by Agrobacterium tumefaciens S33. Appl Environ Microbiol 2019; 85:AEM.00454-19. [PMID: 30926728 DOI: 10.1128/aem.00454-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 03/22/2019] [Indexed: 11/20/2022] Open
Abstract
Agrobacterium tumefaciens S33 degrades nicotine via a novel hybrid of the pyridine and the pyrrolidine pathways. The hybrid pathway consists of at least six steps involved in oxidoreductive reactions before the N-heterocycle can be broken down. Collectively, the six steps allow electron transfer from nicotine and its intermediates to the final acceptor O2 via the electron transport chain (ETC). 6-Hydroxypseudooxynicotine oxidase, renamed 6-hydroxypseudooxynicotine dehydrogenase in this study, has been characterized as catalyzing the fourth step using the artificial electron acceptor 2,6-dichlorophenolindophenol. Here, we used biochemical, genetic, and liquid chromatography-mass spectrometry (LC-MS) analyses to determine that 6-hydroxypseudooxynicotine dehydrogenase utilizes the electron transfer flavoprotein (EtfAB) as the physiological electron acceptor to catalyze the dehydrogenation of pseudooxynicotine, an analogue of the true substrate 6-hydroxypseudooxynicotine, in vivo, into 3-succinoyl-semialdehyde-pyridine. NAD(P)+, O2, and ferredoxin could not function as electron acceptors. The oxygen atom in the aldehyde group of the product 3-succinoyl-semialdehyde-pyridine was verified to be derived from H2O. Disruption of the etfAB genes in the nicotine-degrading gene cluster decreased the growth rate of A. tumefaciens S33 on nicotine but not on 6-hydroxy-3-succinoylpyridine, an intermediate downstream of the hybrid pathway, indicating the requirement of EtfAB for efficient nicotine degradation. The electrons were found to be further transferred from the reduced EtfAB to coenzyme Q by the catalysis of electron transfer flavoprotein:ubiquinone oxidoreductase. These results aid in an in-depth understanding of the electron transfer process and energy metabolism involved in the nicotine oxidation and provide novel insights into nicotine catabolism in bacteria.IMPORTANCE Nicotine has been studied as a model for toxic N-heterocyclic aromatic compounds. Microorganisms can catabolize nicotine via various pathways and conserve energy from its oxidation. Although several oxidoreductases have been characterized to participate in nicotine degradation, the electron transfer involved in these processes is poorly understood. In this study, we found that 6-hydroxypseudooxynicotine dehydrogenase, a key enzyme in the hybrid pyridine and pyrrolidine pathway for nicotine degradation in Agrobacterium tumefaciens S33, utilizes EtfAB as a physiological electron acceptor. Catalyzed by the membrane-associated electron transfer flavoprotein:ubiquinone oxidoreductase, the electrons are transferred from the reduced EtfAB to coenzyme Q, which then could enter into the classic ETC. Thus, the route for electron transport from the substrate to O2 could be constructed, by which ATP can be further sythesized via chemiosmosis to support the baterial growth. These findings provide new knowledge regarding the catabolism of N-heterocyclic aromatic compounds in microorganisms.
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Soluble expression of Thermomicrobium roseum sarcosine oxidase and characterization of N-demethylation activity. MOLECULAR CATALYSIS 2019. [DOI: 10.1016/j.mcat.2018.12.021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Fitzpatrick PF. The enzymes of microbial nicotine metabolism. Beilstein J Org Chem 2018; 14:2295-2307. [PMID: 30202483 PMCID: PMC6122326 DOI: 10.3762/bjoc.14.204] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/20/2018] [Indexed: 12/27/2022] Open
Abstract
Because of nicotine's toxicity and the high levels found in tobacco and in the waste from tobacco processing, there is a great deal of interest in identifying bacteria capable of degrading it. A number of microbial pathways have been identified for nicotine degradation. The first and best-understood is the pyridine pathway, best characterized for Arthrobacter nicotinovorans, in which the first reaction is hydroxylation of the pyridine ring. The pyrrolidine pathway, which begins with oxidation of a carbon-nitrogen bond in the pyrrolidine ring, was subsequently characterized in a number of pseudomonads. Most recently, a hybrid pathway has been described, which incorporates the early steps in the pyridine pathway and ends with steps in the pyrrolidine pathway. This review summarizes the present status of our understanding of these pathways, focusing on what is known about the individual enzymes involved.
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Affiliation(s)
- Paul F Fitzpatrick
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, 78229, USA
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12
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Qu Y, Ma Q, Liu Z, Wang W, Tang H, Zhou J, Xu P. Unveiling the biotransformation mechanism of indole in a Cupriavidus sp. strain. Mol Microbiol 2017; 106:905-918. [PMID: 28963777 DOI: 10.1111/mmi.13852] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2017] [Indexed: 01/13/2023]
Abstract
Indole, an important signaling molecule as well as a typical N-heterocyclic aromatic pollutant, is widespread in nature. However, the biotransformation mechanisms of indole are still poorly studied. Here, we sought to unlock the genetic determinants of indole biotransformation in strain Cupriavidus sp. SHE based on genomics, proteomics and functional studies. A total of 177 proteins were notably altered (118 up- and 59 downregulated) in cells grown in indole mineral salt medium when compared with that in sodium citrate medium. RT-qPCR and gene knockout assays demonstrated that an indole oxygenase gene cluster was responsible for the indole upstream metabolism. A functional indole oxygenase, termed IndA, was identified in the cluster, and its catalytic efficiency was higher than those of previously reported indole oxidation enzymes. Furthermore, the indole downstream metabolism was found to proceed via the atypical CoA-thioester pathway rather than conventional gentisate and salicylate pathways. This unusual pathway was catalyzed by a conserved 2-aminobenzoyl-CoA gene cluster, among which the 2-aminobenzoyl-CoA ligase initiated anthranilate transformation. This study unveils the genetic determinants of indole biotransformation and will provide new insights into our understanding of indole biodegradation in natural environments and its functional studies.
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Affiliation(s)
- Yuanyuan Qu
- State Key Laboratory of Fine Chemicals, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Qiao Ma
- State Key Laboratory of Fine Chemicals, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Ziyan Liu
- State Key Laboratory of Fine Chemicals, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Weiwei Wang
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Hongzhi Tang
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
| | - Jiti Zhou
- State Key Laboratory of Fine Chemicals, Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, People's Republic of China
| | - Ping Xu
- State Key Laboratory of Microbial Metabolism and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China
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Feng C, Zhang J, Li X, Ai B, Han J, Wang Q, Wei T, Xu Y, Li M, Li S, Song C, Li C. Subpathway-CorSP: Identification of metabolic subpathways via integrating expression correlations and topological features between metabolites and genes of interest within pathways. Sci Rep 2016; 6:33262. [PMID: 27625019 PMCID: PMC5021946 DOI: 10.1038/srep33262] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 08/24/2016] [Indexed: 12/23/2022] Open
Abstract
Metabolic pathway analysis is a popular strategy for comprehensively researching metabolites and genes of interest associated with specific diseases. However, the traditional pathway identification methods do not accurately consider the combined effect of these interesting molecules and neglects expression correlations or topological features embedded in the pathways. In this study, we propose a powerful method, Subpathway-CorSP, for identifying metabolic subpathway regions. This method improved on original pathway identification methods by using a subpathway identification strategy and emphasizing expression correlations between metabolites and genes of interest based on topological features within the metabolic pathways. We analyzed a prostate cancer data set and its metastatic sub-group data set with detailed comparison of Subpathway-CorSP with four traditional pathway identification methods. Subpathway-CorSP was able to identify multiple subpathway regions whose entire corresponding pathways were not detected by traditional pathway identification methods. Further evidences indicated that Subpathway-CorSP provided a robust and efficient way of reliably recalling cancer-related subpathways and locating novel subpathways by the combined effect of metabolites and genes. This was a novel subpathway strategy based on systematically considering expression correlations and topological features between metabolites and genes of interest within given pathways.
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Affiliation(s)
- Chenchen Feng
- School of Medical Informatics, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Jian Zhang
- School of Medical Informatics, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Xuecang Li
- School of Medical Informatics, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Bo Ai
- School of Medical Informatics, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Junwei Han
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081,China
| | - Qiuyu Wang
- School of Nursing, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Taiming Wei
- School of Pharmacy, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Yong Xu
- The fifth Affiliated Hospital of Harbin Medical University, Daqing 163319, China
| | - Meng Li
- School of Medical Informatics, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Shang Li
- College of Bioinformatics Science and Technology, Harbin Medical University, Harbin 150081,China
| | - Chao Song
- Department of Pharmacology, Daqing Campus, Harbin Medical University, Daqing 163319, China
| | - Chunquan Li
- School of Medical Informatics, Daqing Campus, Harbin Medical University, Daqing 163319, China
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