1
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Husain NAC, Jamaluddin H, Jonet MA. Functional and structural characterization of a thermostable flavin reductase from Geobacillus mahadii Geo-05. Int J Biol Macromol 2024; 275:133721. [PMID: 38986972 DOI: 10.1016/j.ijbiomac.2024.133721] [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: 12/02/2023] [Revised: 05/25/2024] [Accepted: 07/05/2024] [Indexed: 07/12/2024]
Abstract
Flavin reductases play a vital role in catalyzing the reduction of flavin through NADH or NADPH oxidation. The gene encoding flavin reductase from the thermophilic bacterium Geobacillus mahadii Geo-05 (GMHpaC) was cloned, overexpressed in Escherichia coli BL21 (DE3) pLysS, and purified to homogeneity. The purified recombinant GMHpaC (Class II) contains chromogenic cofactors, evidenced by maximal absorbance peaks at 370 nm and 460 nm. GMHpaC stands out as the most thermostable and pH-tolerant flavin reductase reported to date, retaining up to 95 % catalytic activity after incubation at 70 °C for 30 min and maintaining over 80 % activity within a pH range of 2-12 for 30 min. Furthermore, GMHpaC's catalytic activity increases by 52 % with FMN as a co-factor compared to FAD and riboflavin. GMHpaC, coupled with 4-hydroxyphenylacetate-3-monooxygenase (GMHpaB) from G. mahadii Geo-05, enhances the hydroxylation of 4-hydroxyphenylacetate (HPA) by 85 %. The modeled structure of GMHpaC reveals relatively conserved flavin and NADH binding sites. Modeling and docking studies shed light on structural features and amino acid substitutions that determine GMHpaC's co-factor specificity. The remarkable thermostability, high catalytic activity, and general stability exhibited by GMHpaC position it as a promising enzyme candidate for various industrial applications.
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Affiliation(s)
- Nor Asyikin Che Husain
- Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia; Structural Biology & Functional Omics, Malaysian Genome and Vaccine Institute, 43000 Kajang, Selangor, Malaysia
| | - Haryati Jamaluddin
- Department of Biosciences, Faculty of Science, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia.
| | - Mohd Anuar Jonet
- Structural Biology & Functional Omics, Malaysian Genome and Vaccine Institute, 43000 Kajang, Selangor, Malaysia.
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2
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Shi T, Sun X, Yuan Q, Wang J, Shen X. Exploring the role of flavin-dependent monooxygenases in the biosynthesis of aromatic compounds. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:46. [PMID: 38520003 PMCID: PMC10958861 DOI: 10.1186/s13068-024-02490-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 03/13/2024] [Indexed: 03/25/2024]
Abstract
Hydroxylated aromatic compounds exhibit exceptional biological activities. In the biosynthesis of these compounds, three types of hydroxylases are commonly employed: cytochrome P450 (CYP450), pterin-dependent monooxygenase (PDM), and flavin-dependent monooxygenase (FDM). Among these, FDM is a preferred choice due to its small molecular weight, stable expression in both prokaryotic and eukaryotic fermentation systems, and a relatively high concentration of necessary cofactors. However, the catalytic efficiency of many FDMs falls short of meeting the demands of large-scale production. Additionally, challenges arise from the limited availability of cofactors and compatibility issues among enzyme components. Recently, significant progress has been achieved in improving its catalytic efficiency, but have not yet detailed and informative viewed so far. Therefore, this review emphasizes the advancements in FDMs for the biosynthesis of hydroxylated aromatic compounds and presents a summary of three strategies aimed at enhancing their catalytic efficiency: (a) Developing efficient enzyme mutants through protein engineering; (b) enhancing the supply and rapid circulation of critical cofactors; (c) facilitating cofactors delivery for enhancing FDMs catalytic efficiency. Furthermore, the current challenges and further perspectives on improving catalytic efficiency of FDMs are also discussed.
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Affiliation(s)
- Tong Shi
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China
| | - Xinxiao Sun
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China
| | - Qipeng Yuan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China
| | - Jia Wang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China.
| | - Xiaolin Shen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, 15 Beisanhuan East Road, Chaoyang District, Beijing, 100029, China.
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3
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Sun P, Xu S, Tian Y, Chen P, Wu D, Zheng P. 4-Hydroxyphenylacetate 3-Hydroxylase (4HPA3H): A Vigorous Monooxygenase for Versatile O-Hydroxylation Applications in the Biosynthesis of Phenolic Derivatives. Int J Mol Sci 2024; 25:1222. [PMID: 38279222 PMCID: PMC10816480 DOI: 10.3390/ijms25021222] [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: 01/03/2024] [Revised: 01/16/2024] [Accepted: 01/17/2024] [Indexed: 01/28/2024] Open
Abstract
4-Hydroxyphenylacetate 3-hydroxylase (4HPA3H) is a long-known class of two-component flavin-dependent monooxygenases from bacteria, including an oxygenase component (EC 1.14.14.9) and a reductase component (EC 1.5.1.36), with the latter being accountable for delivering the cofactor (reduced flavin) essential for o-hydroxylation. 4HPA3H has a broad substrate spectrum involved in key biological processes, including cellular catabolism, detoxification, and the biosynthesis of bioactive molecules. Additionally, it specifically hydroxylates the o-position of the C4 position of the benzene ring in phenolic compounds, generating high-value polyhydroxyphenols. As a non-P450 o-hydroxylase, 4HPA3H offers a viable alternative for the de novo synthesis of valuable natural products. The enzyme holds the potential to replace plant-derived P450s in the o-hydroxylation of plant polyphenols, addressing the current significant challenge in engineering specific microbial strains with P450s. This review summarizes the source distribution, structural properties, and mechanism of 4HPA3Hs and their application in the biosynthesis of natural products in recent years. The potential industrial applications and prospects of 4HPA3H biocatalysts are also presented.
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Affiliation(s)
| | | | | | | | | | - Pu Zheng
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China; (P.S.); (Y.T.); (P.C.); (D.W.)
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4
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Xu S, Zheng P, Sun P, Chen P, Wu D. Biosynthesis of 3-Hydroxyphloretin Using Rational Design of 4-Hydroxyphenylacetate 3-Monooxygenase. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2023; 71:19457-19464. [PMID: 38029276 DOI: 10.1021/acs.jafc.3c06479] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
The compound 3-hydroxyphloretin is a typical dihydrochalcone that can be obtained in plants by the 3-hydroxylation of phloretin. Here, the flavin-dependent two-component monooxygenase (HpaBC) derived from Pseudomonas aeruginosa was used to convert phloretin into 3-hydroxyphloretin. Following molecular docking and sequence alignment, modifications to the substrate pocket and loop of PaHpaBC were rationally designed, and mutant residues were selected. The results showed that the mutant Q212G/F292A/Q376N gave the best yield of 3-hydroxyphloretin and showed improved catalytic efficiency. Under optimal reaction condition, 2.03 g/L of 3-hydroxyphloretin was produced in the whole-cell catalysis experiment. Molecular docking and molecular dynamics simulations were used to analyze mutants and elucidate the potential mechanism. It was found that the increase in 3-hydroxyphloretin yield was due to the improvement in the flexibility of the loop and the expansion of its substrate pocket. This strategy based on loop and substrate pocket modification has significance in the engineering of PaHpaB.
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Affiliation(s)
- Shuping Xu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Pu Zheng
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Ping Sun
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Pengcheng Chen
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Dan Wu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
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5
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Phintha A, Chaiyen P. Unifying and versatile features of flavin-dependent monooxygenases: Diverse catalysis by a common C4a-(hydro)peroxyflavin. J Biol Chem 2023; 299:105413. [PMID: 37918809 PMCID: PMC10696468 DOI: 10.1016/j.jbc.2023.105413] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 10/18/2023] [Accepted: 10/22/2023] [Indexed: 11/04/2023] Open
Abstract
Flavin-dependent monooxygenases (FDMOs) are known for their remarkable versatility and for their crucial roles in various biological processes and applications. Extensive research has been conducted to explore the structural and functional relationships of FDMOs. The majority of reported FDMOs utilize C4a-(hydro)peroxyflavin as a reactive intermediate to incorporate an oxygen atom into a wide range of compounds. This review discusses and analyzes recent advancements in our understanding of the structural and mechanistic features governing the enzyme functions. State-of-the-art discoveries related to common and distinct structural properties governing the catalytic versatility of the C4a-(hydro)peroxyflavin intermediate in selected FDMOs are discussed. Specifically, mechanisms of hydroxylation, dehalogenation, halogenation, and light-emitting reactions by FDMOs are highlighted. We also provide new analysis based on the structural and mechanistic features of these enzymes to gain insights into how the same intermediate can be harnessed to perform a wide variety of reactions. Challenging questions to obtain further breakthroughs in the understanding of FDMOs are also proposed.
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Affiliation(s)
- Aisaraphon Phintha
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand.
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6
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Yang K, Zhang Q, Zhao W, Hu S, Lv C, Huang J, Mei J, Mei L. Advances in 4-Hydroxyphenylacetate-3-hydroxylase Monooxygenase. Molecules 2023; 28:6699. [PMID: 37764475 PMCID: PMC10537072 DOI: 10.3390/molecules28186699] [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: 08/28/2023] [Revised: 09/16/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Catechols have important applications in the pharmaceutical, food, cosmetic, and functional material industries. 4-hydroxyphenylacetate-3-hydroxylase (4HPA3H), a two-component enzyme system comprising HpaB (monooxygenase) and HpaC (FAD oxidoreductase), demonstrates significant potential for catechol production because it can be easily expressed, is highly active, and exhibits ortho-hydroxylation activity toward a broad spectrum of phenol substrates. HpaB determines the ortho-hydroxylation efficiency and substrate spectrum of the enzyme; therefore, studying its structure-activity relationship, improving its properties, and developing a robust HpaB-conducting system are of significance and value; indeed, considerable efforts have been made in these areas in recent decades. Here, we review the classification, molecular structure, catalytic mechanism, primary efforts in protein engineering, and industrial applications of HpaB in catechol synthesis. Current trends in the further investigation of HpaB are also discussed.
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Affiliation(s)
- Kai Yang
- Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
- School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China
| | - Qianchao Zhang
- School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China
| | - Weirui Zhao
- School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China
| | - Sheng Hu
- School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China
| | - Changjiang Lv
- Department of Chemical and Biological Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Jun Huang
- Department of Chemical and Biological Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Jiaqi Mei
- Hangzhou Huadong Medicine Group Co., Ltd., Hangzhou 310011, China
| | - Lehe Mei
- Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
- School of Biological and Chemical Engineering, Ningbo Tech University, Ningbo 315100, China
- Jinhua Advanced Research Institute, Jinhua 321019, China
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7
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Zhang Q, Jin Y, Yang K, Hu S, Lv C, Huang J, Mei J, Zhao W, Mei L. Modification of the 4-Hydroxyphenylacetate-3-hydroxylase Substrate Pocket to Increase Activity towards Resveratrol. Molecules 2023; 28:5602. [PMID: 37513473 PMCID: PMC10384689 DOI: 10.3390/molecules28145602] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 07/16/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
4-Hydroxyphenylacetate-3-hydroxylase (4HPA3H; EC 1.14.14.9) is a heterodimeric flavin-dependent monooxygenase complex that catalyzes the ortho-hydroxylation of resveratrol to produce piceatannol. Piceatannol has various health benefits and valuable applications in food, medicine, and cosmetics. Enhancing the catalytic activity of 4HPA3H toward resveratrol has the potential to benefit piceatannol production. In this study, the critical amino acid residues in the substrate pocket of 4HPA3H that affect its activity toward resveratrol were identified using semi-rational engineering. Two key amino acid sites (I157 and A211) were discovered and the simultaneous "best" mutant I157L/A211D enabled catalytic efficiency (Kcat/Km-resveratrol) to increase by a factor of 4.7-fold. Molecular dynamics simulations indicated that the increased flexibility of the 4HPA3H substrate pocket has the potential to improve the catalytic activity of the enzyme toward resveratrol. On this basis, we produced 3.78 mM piceatannol by using the mutant I157L/A211D whole cells. In this study, we successfully developed a highly active 4HPA3H variant for the hydroxylation of resveratrol to piceatannol.
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Affiliation(s)
- Qianchao Zhang
- College of Pharmaceutical Science, Zhejiang University of Technology, Hangzhou 310014, China
- School of Biological and Chemical Engineering, NingboTech University, Ningbo 315100, China
| | - Yuning Jin
- School of Biological and Chemical Engineering, NingboTech University, Ningbo 315100, China
| | - Kai Yang
- Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
| | - Sheng Hu
- School of Biological and Chemical Engineering, NingboTech University, Ningbo 315100, China
| | - Changjiang Lv
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Jun Huang
- School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou 310023, China
| | - Jiaqi Mei
- Hangzhou Huadong Medicine Group Co., Ltd., Hangzhou 310011, China
| | - Weirui Zhao
- School of Biological and Chemical Engineering, NingboTech University, Ningbo 315100, China
| | - Lehe Mei
- School of Biological and Chemical Engineering, NingboTech University, Ningbo 315100, China
- Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027, China
- Jinhua Advanced Research Institute, Jinhua 321019, China
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8
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Wang H, Wang S, Wang J, Shen X, Feng X, Yuan S, Sun X, Yuan Q. Engineering a Prokaryotic Non-P450 Hydroxylase for 3'-Hydroxylation of Flavonoids. ACS Synth Biol 2022; 11:3865-3873. [PMID: 36321874 DOI: 10.1021/acssynbio.2c00430] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Plant-derived cytochrome P450-dependent flavonoid 3'-hydroxylases are the rate-limiting enzymes in flavonoid biosynthesis. In this study, the large component (HpaB) of a prokaryotic 4-hydroxyphenylacetate (4-HPA) 3-hydroxylase was engineered for efficient 3'-hydroxylation of naringenin. First, we selected four HpaBs through database search and phylogenetic analysis and compared their catalytic activities toward 4-HPA and naringenin. HpaB from Rhodococcus opacus B-4 (RoHpaB) showed better preference toward naringenin. To elucidate the underlying mechanism, we analyzed the structural differences of HpaBs through homologous modeling, molecular docking, and molecular dynamics simulation, and the substrate preference of RoHpaB was mainly attributed to the shorter chain length of loop 212-222 and the larger substrate binding pocket. RoHpaB was further engineered by alanine scanning and structural replacement, and the RoHpaBY215A variant was obtained, whose catalytic efficiency (kcat/Km) toward naringenin is 25.3 times higher than that of RoHpaB. In addition, RoHpaBY215A also showed significantly improved activity toward flavonoids apigenin and kaempferol. This work opens the possibility of using engineered HpaB as a versatile hydroxylase to produce functionalized flavonoids.
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Affiliation(s)
- Hongyan Wang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Shiyu Wang
- Research Center for Computer-Aided Drug Discovery, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Jia Wang
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiaolin Shen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xudong Feng
- Institute of Biochemical Engineering, Department of Chemical Engineering, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, China
| | - Shuguang Yuan
- Research Center for Computer-Aided Drug Discovery, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Xinxiao Sun
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Qipeng Yuan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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9
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Nozawa D, Matsuyama A, Furuya T. Biocatalytic synthesis and evaluation of antioxidant and antibacterial activities of hydroxyequols. Bioorg Med Chem Lett 2022; 73:128908. [PMID: 35902062 DOI: 10.1016/j.bmcl.2022.128908] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Revised: 07/15/2022] [Accepted: 07/21/2022] [Indexed: 11/29/2022]
Abstract
Hydroxyequols are promising analogues of the biologically active flavonoid, equol. We recently found that the flavin-dependent monooxygenase HpaBro-3 of Rhodococcus opacus regioselectively synthesizes 3'-hydroxyequol from equol, whereas HpaBpl-1 of Photorhabdus luminescens synthesizes 6-hydroxyequol. In this study, we investigated the cascade synthesis of a dihydroxyequol compound from equol using these two enzymes. When Escherichia coli cells expressing HpaBro-3 and cells expressing HpaBpl-1 were simultaneously incubated with equol, the cells efficiently synthesized 6,3'-dihydroxyequol (8.7 mM, 2.4 g/L) via 3'- and 6-hydroxyequols in one pot. The antioxidant activity of the equol derivatives increased with an increase in the number of hydroxyl groups on the equol scaffold. 6,3'-Dihydroxyequol exhibited potent antioxidant activity. In addition, 6-hydroxyequol significantly inhibited the growth of E. coli. Cell survival studies suggested that 6-hydroxyequol is a bactericidal rather than bacteriostatic compound. To our knowledge, this is the first report describing the antibacterial activity of hydroxyequols.
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Affiliation(s)
- Daiki Nozawa
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | | | - Toshiki Furuya
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
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10
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Liu Y, Liu H, Hu H, Ng KR, Yang R, Lyu X. De Novo Production of Hydroxytyrosol by Metabolic Engineering of Saccharomyces cerevisiae. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:7490-7499. [PMID: 35649155 DOI: 10.1021/acs.jafc.2c02137] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Hydroxytyrosol is an olive-derived phenolic compound of increasing commercial interest due to its health-promoting properties. In this study, a high-yield hydroxytyrosol-producing Saccharomyces cerevisiae cell factory was established via a comprehensive metabolic engineering scheme. First, de novo biosynthetic pathway of hydroxytyrosol was constructed in yeast by gene screening and overexpression of different phenol hydroxylases, among which paHD (from Pseudomonas aeruginosa) displayed the best catalytic performance. Next, hydroxytyrosol precursor supply was enhanced via a multimodular engineering approach: elimination of tyrosine feedback inhibition through genomic integration of aro4K229L and aro7G141S, construction of an aromatic aldehyde synthase (AAS)-based tyrosine metabolic pathway, and redistribution of metabolic flux between glycolytic pathway and pentose phosphate pathway (PPP) by introducing the exogenous gene Bbxfpkopt. As a result, the titer of hydroxytyrosol was improved by 6.88-fold. Finally, a glucose-responsive dynamic regulation system based on GAL80 deletion was implemented, resulting in the final hydroxytyrosol yields of 308.65 mg/L and 167.98 mg/g cell mass, the highest known from de novo production in S. cerevisiae to date.
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Affiliation(s)
- Yingjie Liu
- School of Food Science and Technology, Jiangnan University, 214122 Wuxi, China
| | - Han Liu
- School of Food Science and Technology, Jiangnan University, 214122 Wuxi, China
| | - Haitao Hu
- School of Food Science and Technology, Jiangnan University, 214122 Wuxi, China
| | - Kuan Rei Ng
- Food Science and Technology Programme, Nanyang Technological University, 62 Nanyang Drive, Singapore 637459, Singapore
| | - Ruijin Yang
- School of Food Science and Technology, Jiangnan University, 214122 Wuxi, China
| | - Xiaomei Lyu
- School of Food Science and Technology, Jiangnan University, 214122 Wuxi, China
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11
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Song H, Lee PG, Kim J, Kim J, Lee SH, Kim H, Lee UJ, Kim JY, Kim EJ, Kim BG. Regioselective One-Pot Synthesis of Hydroxy-(S)-Equols Using Isoflavonoid Reductases and Monooxygenases and Evaluation of the Hydroxyequol Derivatives as Selective Estrogen Receptor Modulators and Antioxidants. Front Bioeng Biotechnol 2022; 10:830712. [PMID: 35402392 PMCID: PMC8987157 DOI: 10.3389/fbioe.2022.830712] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 01/31/2022] [Indexed: 12/22/2022] Open
Abstract
Several regiospecific enantiomers of hydroxy-(S)-equol (HE) were enzymatically synthesized from daidzein and genistein using consecutive reduction (four daidzein-to-equol–converting reductases) and oxidation (4-hydroxyphenylacetate 3-monooxygenase, HpaBC). Despite the natural occurrence of several HEs, most of them had not been studied owing to the lack of their preparation methods. Herein, the one-pot synthesis pathway of 6-hydroxyequol (6HE) was developed using HpaBC (EcHpaB) from Escherichia coli and (S)-equol-producing E. coli, previously developed by our group. Based on docking analysis of the substrate or products, a potential active site and several key residues for substrate binding were predicted to interpret the (S)-equol hydroxylation regioselectivity of EcHpaB. Through investigating mutations on the key residues, the T292A variant was verified to display specific mono-ortho-hydroxylation activity at C6 without further 3′-hydroxylation. In the consecutive oxidoreductive bioconversion using T292A, 0.95 mM 6HE could be synthesized from 1 mM daidzein, while 5HE and 3′HE were also prepared from genistein and 3′-hydroxydaidzein (3′HD or 3′-ODI), respectively. In the following efficacy tests, 3′HE and 6HE showed about 30∼200-fold higher EC50 than (S)-equol in both ERα and ERβ, and they did not have significant SERM efficacy except 6HE showing 10% lower β/α ratio response than that of 17β-estradiol. In DPPH radical scavenging assay, 3′HE showed the highest antioxidative activity among the examined isoflavone derivatives: more than 40% higher than the well-known 3′HD. In conclusion, we demonstrated that HEs could be produced efficiently and regioselectively through the one-pot bioconversion platform and evaluated estrogenic and antioxidative activities of each HE regio-isomer for the first time.
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Affiliation(s)
- Hanbit Song
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Pyung-Gang Lee
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
- Institute of Engineering Research, Seoul National University, Seoul, South Korea
| | - Junyeob Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Joonwon Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Sang-Hyuk Lee
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Hyun Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Uk-Jae Lee
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Jin Young Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
| | - Eun-Jung Kim
- Bio-MAX/N-Bio Institute, Seoul National University, Seoul, South Korea
| | - Byung-Gee Kim
- School of Chemical and Biological Engineering, Seoul National University, Seoul, South Korea
- Institute of Molecular Biology and Genetics, Seoul National University, Seoul, South Korea
- Bio-MAX/N-Bio Institute, Seoul National University, Seoul, South Korea
- Institute for Sustainable Development (ISD), Seoul National University, Seoul, South Korea
- *Correspondence: Byung-Gee Kim,
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12
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Dippe M, Herrmann S, Pecher P, Funke E, Pietzsch M, Wessjohann L. Engineered bacterial flavin-dependent monooxygenases for the regiospecific hydroxylation of polycyclic phenols. Chembiochem 2022; 23:e202100480. [PMID: 34979058 PMCID: PMC9303722 DOI: 10.1002/cbic.202100480] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 12/06/2021] [Indexed: 11/06/2022]
Abstract
4-Hydroxyphenylacetate 3-hydroxylase (4HPA3H), a flavin-dependent monooxygenase from E. coli that catalyzes the hydroxylation of monophenols to catechols, was modified by rational re-design to convert also more bulky substrates, especially phenolic natural products like phenylpropanoids, flavones or coumarins. Selected amino acid positions in the binding pocket of 4HPA3H were exchanged by residues from the homologous protein from Pseudomonas aeruginosa, yielding variants with improved conversion of spacious substrates such as the flavonoid naringenin or the alkaloid mimetic 2-hydroxycarbazole. Reactions were followed by an adapted Fe(III)-catechol chromogenic assay selective for the products. Especially substitution of the residue Y301 facilitated modulation of substrate specificity: introduction of non-aromatic but hydrophobic (iso)leucine resulted in the preference of the substrate ferulic acid (having a guaiacyl (guajacyl) moiety, part of the vanilloid motif) over unsubstituted monophenols. The in vivo (whole-cell biocatalysts) and in vitro (three-enzyme cascade) transformations of substrates by 4HPA3H and its optimized variants was strictly regiospecific and proceeded without generation of by-products.
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Affiliation(s)
- Martin Dippe
- Leibniz-Institut für Pflanzenbiochemie: Leibniz-Institut fur Pflanzenbiochemie, Bioorganic Chemistry, Weinberg 3, D-06120, Halle/Saale, GERMANY
| | - Susann Herrmann
- Leibniz-Institut für Pflanzenbiochemie: Leibniz-Institut fur Pflanzenbiochemie, Bioorganic Chemistry, Weinberg 3, D-06120, Halle, GERMANY
| | - Pascal Pecher
- Leibniz Institute of Plant Biochemistry: Leibniz-Institut fur Pflanzenbiochemie, Bioorganic Chemistry, GERMANY
| | - Evelyn Funke
- Leibniz-Institut fur Pflanzenbiochemie, Bioorganic Chemistry, GERMANY
| | - Markus Pietzsch
- Martin-Luther-Universität Halle-Wittenberg: Martin-Luther-Universitat Halle-Wittenberg, Institute of Pharmacy, Weinbergweg 22, D-06120, Halle, GERMANY
| | - Ludger Wessjohann
- Leibniz-Institute of Plant Biochemistry, Bioorganic Chemistry, Weinberg 3, 06120, Halle Saale, GERMANY
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Single-Component and Two-Component para-Nitrophenol Monooxygenases: Structural Basis for Their Catalytic Difference. Appl Environ Microbiol 2021; 87:e0117121. [PMID: 34469195 DOI: 10.1128/aem.01171-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
para-Nitrophenol (PNP) is a hydrolytic product of organophosphate insecticides, such as parathion and methylparathion, in soil. Aerobic microbial degradation of PNP has been classically shown to proceed via the "hydroquinone (HQ) pathway" in Gram-negative degraders, whereas it proceeds via the "benzenetriol (BT) pathway" in Gram-positive ones. The "HQ pathway" is initiated by a single-component PNP 4-monooxygenase and the "BT pathway" by a two-component PNP 2-monooxygenase. Their regioselectivity intrigued us enough to investigate their catalytic difference through structural study. PnpA1 is the oxygenase component of the two-component PNP 2-monooxygenase from Gram-positive Rhodococcus imtechensis strain RKJ300. It also catalyzes the hydroxylation of 4-nitrocatechol (4NC) and 2-chloro-4-nitrophenol (2C4NP). However, the mechanisms are unknown. Here, PnpA1 was structurally determined to be a member of the group D flavin-dependent monooxygenases with an acyl coenzyme A (acyl-CoA) dehydrogenase fold. The crystal structure and site-directed mutagenesis underlined the direct involvement of Arg100 and His293 in catalysis. The bulky side chain of Val292 was proposed to push the substrate toward flavin adenine dinucleotide (FAD), hence positioning the substrate properly. An N450A variant was found with improved activity for 4NC and 2C4NP-probably because of the reduced steric hindrance. PnpA1 shows an obvious difference in substrate selectivity with its close homologues TcpA and TftD, which may be caused by the unique Thr296 and a different conformation in the loop from positions 449 to 454 (loop 449-454). Above all, our study allows structural comparison between the two types of PNP monooxygenases. An explanation that accounts for their regioselectivity was proposed: the different PNP binding manners determine their choice of ortho- or para-hydroxylation on PNP. IMPORTANCE Single-component PNP monoxygenases hydroxylate PNP at the 4 position, while two-component ones do so at the 2 position. However, their catalytic and structural differences remain elusive. The structure of single-component PNP 4-monooxygenase has previously been determined. In this study, to illustrate their catalytic difference, we resolved the crystal structure of PnpA1, a typical two-component PNP 2-monooxygenase. The roles of several key amino acid residues in substrate binding and catalysis were revealed, and a variant with improved activities toward 4NC and 2C4NP was obtained. Moreover, through comparison of the two types of PNP monooxygenases, a hypothesis was proposed to account for their catalytic difference, which gives us a better understanding of these two similar reactions at the molecular level. In addition, these results will also be of further aid in rational design of enzymes in bioremediation and biosynthesis.
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Pimviriyakul P, Jaruwat A, Chitnumsub P, Chaiyen P. Structural insights into a flavin-dependent dehalogenase HadA explain catalysis and substrate inhibition via quadruple π-stacking. J Biol Chem 2021; 297:100952. [PMID: 34252455 PMCID: PMC8342789 DOI: 10.1016/j.jbc.2021.100952] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 06/24/2021] [Accepted: 07/08/2021] [Indexed: 12/20/2022] Open
Abstract
HadA is a flavin-dependent monooxygenase catalyzing hydroxylation plus dehalogenation/denitration, which is useful for biodetoxification and biodetection. In this study, the X-ray structure of wild-type HadA (HadAWT) co-complexed with reduced FAD (FADH-) and 4-nitrophenol (4NP) (HadAWT-FADH--4NP) was solved at 2.3-Å resolution, providing the first full package (with flavin and substrate bound) structure of a monooxygenase of this type. Residues Arg101, Gln158, Arg161, Thr193, Asp254, Arg233, and Arg439 constitute a flavin-binding pocket, whereas the 4NP-binding pocket contains the aromatic side chain of Phe206, which provides π-π stacking and also is a part of the hydrophobic pocket formed by Phe155, Phe286, Thr449, and Leu457. Based on site-directed mutagenesis and stopped-flow experiments, Thr193, Asp254, and His290 are important for C4a-hydroperoxyflavin formation with His290, also serving as a catalytic base for hydroxylation. We also identified a novel structural motif of quadruple π-stacking (π-π-π-π) provided by two 4NP and two Phe441 from two subunits. This motif promotes 4NP binding in a nonproductive dead-end complex, which prevents C4a-hydroperoxy-FAD formation when HadA is premixed with aromatic substrates. We also solved the structure of the HadAPhe441Val-FADH--4NP complex at 2.3-Å resolution. Although 4NP can still bind to this variant, the quadruple π-stacking motif was disrupted. All HadAPhe441 variants lack substrate inhibition behavior, confirming that quadruple π-stacking is a main cause of dead-end complex formation. Moreover, the activities of these HadAPhe441 variants were improved by ⁓20%, suggesting that insights gained from the flavin-dependent monooxygenases illustrated here should be useful for future improvement of HadA's biocatalytic applications.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology, Pathumthani, Thailand.
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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Ke Z, Lan M, Yang T, Jia W, Gou Z, Chen K, Jiang J. A two-component monooxygenase for continuous denitration and dechlorination of chlorinated 4-nitrophenol in Ensifer sp. strain 22-1. ENVIRONMENTAL RESEARCH 2021; 198:111216. [PMID: 33971135 DOI: 10.1016/j.envres.2021.111216] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 06/12/2023]
Abstract
The environmental fates of chlorinated 4-nitrophenols, 2,6-dichloro-4-nitrophenol (2,6-DCNP) and 2-chloro-4-nitrophenol (2C4NP), mediated via microbial catabolism have attracted great attention due to their high toxicity and persistence in the environment. In this study, a strain of Ensifer sp. 22-1 that was capable of degrading both 2,6-DCNP and 2C4NP was isolated from a halogenated aromatic-contaminated soil sample. A gene cluster cnpBADCERM was predicted to be involved in the catabolism of 2,6-DCNP and 2C4NP based on genome sequence analysis. A two-component monooxygenase CnpAB, composed of an oxygenase component (CnpA) and a reductase component (CnpB), was confirmed to catalyze the continuous denitration and dechlorination of 2,6-DCNP and 2C4NP to 6-chlorohydroxyquinol (6-CHQ) and hydroxyquinol (HQ), respectively. Knockout of cnpA resulted in the complete loss of the capacity for strain 22-1 to degrade 2,6-DCNP and 2C4NP. Homologous modeling and docking showed that Val155~Ala159, Phe206~Pro209 and Phe446~Arg461 of CnpA participated in the formation of the FAD-binding pocket, and Arg101, Val155 and Asn447 formed hydrogen bonds with 2,6-DCNP/2C4NP in the substrate-binding pocket. This work characterized a new two-component monooxygenase for 2,6-DCNP and 2C4NP, and enriched our understanding of the degradation mechanism of chlorinated nitrophenols (CNPs) by microorganisms.
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Affiliation(s)
- Zhuang Ke
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
| | - Minjian Lan
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
| | - Tunan Yang
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
| | - Weibin Jia
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
| | - Zhenjiu Gou
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China
| | - Kai Chen
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China.
| | - Jiandong Jiang
- Department of Microbiology, Key Lab of Environmental Microbiology for Agriculture, Ministry of Agriculture, College of Life Sciences, Nanjing Agricultural University, 210095, Nanjing, China; Jiangsu Key Lab for Solid Organic Waste Utilization, 210095, Nanjing, China.
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16
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Hexachlorobenzene Monooxygenase Substrate Selectivity and Catalysis: Structural and Biochemical Insights. Appl Environ Microbiol 2020; 87:AEM.01965-20. [PMID: 33097503 DOI: 10.1128/aem.01965-20] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/14/2020] [Indexed: 01/14/2023] Open
Abstract
Hexachlorobenzene (HCB), as one of the persistent organic pollutants (POPs) and a possible human carcinogen, is especially resistant to biodegradation. In this study, HcbA1A3, a distinct flavin-N5-peroxide-utilizing enzyme and the sole known naturally occurring aerobic HCB dechlorinase, was biochemically characterized. Its apparent preference for HCB in binding affinity revealed that HcbA1 could oxidize only HCB rather than less-chlorinated benzenes such as pentachlorobenzene and tetrachlorobenzenes. In addition, the crystal structure of HcbA1 and its complex with flavin mononucleotide (FMN) were resolved, revealing HcbA1 to be a new member of the bacterial luciferase-like family. A much smaller substrate-binding pocket of HcbA1 than is seen with its close homologues suggests a requirement of limited space for catalysis. In the active center, Tyr362 and Asp315 are necessary in maintaining the normal conformation of HcbA1, while Arg311, Arg314, Phe10, Val59, and Met12 are pivotal for the substrate affinity. They are supposed to place HCB at a productive orientation through multiple interactions. His17, with its close contact with the site of oxidation of HCB, probably fixes the target chlorine atom and stabilizes reaction intermediates. The enzymatic characteristics and crystal structures reported here provide new insights into the substrate specificity and catalytic mechanism of HcbA1, which paves the way for its rational engineering and application in the bioremediation of HCB-polluted environments.IMPORTANCE As an endocrine disrupter and possible carcinogen to human beings, hexachlorobenzene (HCB) is especially resistant to biodegradation, largely due to difficulty in its dechlorination. The lack of knowledge of HCB dechlorinases limits their application in bioremediation. Recently, an HCB monooxygenase, HcbA1A3, representing the only naturally occurring aerobic HCB dechlorinase known so far, was reported. Here, we report its biochemical and structural characterization, providing new insights into its substrate selectivity and catalytic mechanism. This research also increases our understanding of HCB dechlorinases and flavin-N5-peroxide-utilizing enzymes.
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Abstract
Many flavin-dependent phenolic hydroxylases (monooxygenases) have been extensively investigated. Their crystal structures and reaction mechanisms are well understood. These enzymes belong to groups A and D of the flavin-dependent monooxygenases and can be classified as single-component and two-component flavin-dependent monooxygenases. The insertion of molecular oxygen into the substrates catalyzed by these enzymes is beneficial for modifying the biological properties of phenolic compounds and their derivatives. This chapter provides an in-depth discussion of the structural features of single-component and two-component flavin-dependent phenolic hydroxylases. The reaction mechanisms of selected enzymes, including 3-hydroxy-benzoate 4-hydroxylase (PHBH) and 3-hydroxy-benzoate 6-hydroxylase as representatives of single-component enzymes and 3-hydroxyphenylacetate 4-hydroxylase (HPAH) as a representative of two-component enzymes, are discussed in detail. This chapter comprises the following four main parts: general reaction, structures, reaction mechanisms, and enzyme engineering for biocatalytic applications. Enzymes belonging to the same group catalyze similar reactions but have different unique structural features to control their reactivity to substrates and the formation and stabilization of C4a-hydroperoxyflavin. Protein engineering has been employed to improve the ability to use these enzymes to synthesize valuable compounds. A thorough understanding of the structural and mechanistic features controlling enzyme reactivity is useful for enzyme redesign and enzyme engineering for future biocatalytic applications.
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Affiliation(s)
- Pirom Chenprakhon
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom, Thailand.
| | - Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, Thailand; Department of Biotechnology, Faculty of Engineering and Industrial Technology, Silpakorn University, Nakhon Pathom, Thailand
| | - Chanakan Tongsook
- Department of Chemistry, Faculty of Science, Silpakorn University, Nakhon Pathom, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong, Thailand
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18
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Kim H, Kim S, Kim D, Yoon SH. A single amino acid substitution in aromatic hydroxylase (HpaB) of Escherichia coli alters substrate specificity of the structural isomers of hydroxyphenylacetate. BMC Microbiol 2020; 20:109. [PMID: 32375644 PMCID: PMC7201708 DOI: 10.1186/s12866-020-01798-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 04/22/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND A broad range of aromatic compounds can be degraded by enteric bacteria, and hydroxyphenylacetic acid (HPA) degrading bacteria are the most widespread. Majority of Escherichia coli strains can use both the structural isomers of HPA, 3HPA and 4HPA, as the sole carbon source, which are catabolized by the same pathway whose associated enzymes are encoded by hpa gene cluster. Previously, we observed that E. coli B REL606 grew only on 4HPA, while E. coli B BL21(DE3) grew on 3HPA as well as 4HPA. RESULTS In this study, we report that a single amino acid in 4-hydroxyphenylacetate 3-hydroxylase (HpaB) of E. coli determines the substrate specificity of HPA isomers. Alignment of protein sequences encoded in hpa gene clusters of BL21(DE3) and REL606 showed that there was a difference of only one amino acid (position 379 in HpaB) between the two, viz., Arg in BL21(DE3) and Cys in REL606. REL606 cells expressing HpaB having Arg379 could grow on 3HPA, whereas those expressing HpaB with Gly379 or Ser379 could not. Structural analysis suggested that the amino acid residue at position 379 of HpaB is located not in the active site, but in the vicinity of the 4HPA binding site, and that it plays an important role in mediating the entrance and stable binding of substrates to the active site. CONCLUSIONS The arginine residue at position 379 of HpaB is critical for 3HPA recognition. Information regarding the effect of amino acid residues on the substrate specificity of structural isomers can facilitate in designing hydoxylases with high catalytic efficiency and versatility.
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Affiliation(s)
- Hanseol Kim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, 05029, Republic of Korea
| | - Sinyeon Kim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, 05029, Republic of Korea
| | - Dohyeon Kim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, 05029, Republic of Korea
| | - Sung Ho Yoon
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, 05029, Republic of Korea.
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19
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Yao J, He Y, Su N, Bharath SR, Tao Y, Jin JM, Chen W, Song H, Tang SY. Developing a highly efficient hydroxytyrosol whole-cell catalyst by de-bottlenecking rate-limiting steps. Nat Commun 2020; 11:1515. [PMID: 32251291 PMCID: PMC7090077 DOI: 10.1038/s41467-020-14918-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 02/11/2020] [Indexed: 01/18/2023] Open
Abstract
Hydroxytyrosol is an antioxidant free radical scavenger that is biosynthesized from tyrosine. In metabolic engineering efforts, the use of the mouse tyrosine hydroxylase limits its production. Here, we design an efficient whole-cell catalyst of hydroxytyrosol in Escherichia coli by de-bottlenecking two rate-limiting enzymatic steps. First, we replace the mouse tyrosine hydroxylase by an engineered two-component flavin-dependent monooxygenase HpaBC of E. coli through structure-guided modeling and directed evolution. Next, we elucidate the structure of the Corynebacterium glutamicum VanR regulatory protein complexed with its inducer vanillic acid. By switching its induction specificity from vanillic acid to hydroxytyrosol, VanR is engineered into a hydroxytyrosol biosensor. Then, with this biosensor, we use in vivo-directed evolution to optimize the activity of tyramine oxidase (TYO), the second rate-limiting enzyme in hydroxytyrosol biosynthesis. The final strain reaches a 95% conversion rate of tyrosine. This study demonstrates the effectiveness of sequentially de-bottlenecking rate-limiting steps for whole-cell catalyst development. Whole-cell catalyst-based hydroxytyrosol production is low. Here, the authors increase the efficiency of its production in E. coli by de-bottlenecking two enzymatic steps catalyzed by monooxygenase and tyramine oxidase using structure-based enzyme redesign or in vivo-directed evolution with the aid of a newly developed biosensor.
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Affiliation(s)
- Jun Yao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yang He
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore, Singapore
| | - Nannan Su
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore, Singapore
| | | | - Yong Tao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jian-Ming Jin
- Beijing Key Laboratory of Plant Resources Research and Development, Beijing Technology and Business University, Beijing, China.
| | - Wei Chen
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
| | - Haiwei Song
- Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore, Singapore.
| | - Shuang-Yan Tang
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
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20
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Soule J, Gnann AD, Gonzalez R, Parker MJ, McKenna KC, Nguyen SV, Phan NT, Wicht DK, Dowling DP. Structure and function of the two-component flavin-dependent methanesulfinate monooxygenase within bacterial sulfur assimilation. Biochem Biophys Res Commun 2020; 522:107-112. [PMID: 31753487 DOI: 10.1016/j.bbrc.2019.11.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 11/02/2019] [Indexed: 10/25/2022]
Abstract
Methyl sulfur compounds are a rich source of environmental sulfur for microorganisms, but their use requires redox systems. The bacterial sfn and msu operons contain two-component flavin-dependent monooxygenases for dimethylsulfone (DMSO2) assimilation: SfnG converts DMSO2 to methanesulfinate (MSI-), and MsuD converts methanesulfonate (MS-) to sulfite. However, the enzymatic oxidation of MSI- to MS- has not been demonstrated, and the function of the last enzyme of the msu operon (MsuC) is unresolved. We employed crystallographic and biochemical studies to identify the function of MsuC from Pseudomonas fluorescens. The crystal structure of MsuC adopts the acyl-CoA dehydrogenase fold with putative binding sites for flavin and MSI-, and functional assays of MsuC in the presence of its oxidoreductase MsuE, FMN, and NADH confirm the enzymatic generation of MS-. These studies reveal that MsuC converts MSI- to MS- in sulfite biosynthesis from DMSO2.
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Affiliation(s)
- Jess Soule
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Andrew D Gnann
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Reyaz Gonzalez
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Mackenzie J Parker
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Kylie C McKenna
- Department of Chemistry and Biochemistry, Suffolk University, Boston, MA, 02108, USA
| | - Son V Nguyen
- Department of Chemistry and Biochemistry, Suffolk University, Boston, MA, 02108, USA
| | - Ngan T Phan
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA; Department of Chemistry and Biochemistry, Suffolk University, Boston, MA, 02108, USA
| | - Denyce K Wicht
- Department of Chemistry and Biochemistry, Suffolk University, Boston, MA, 02108, USA.
| | - Daniel P Dowling
- Department of Chemistry, University of Massachusetts Boston, Boston, MA, 02125, USA.
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21
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Chenprakhon P, Wongnate T, Chaiyen P. Monooxygenation of aromatic compounds by flavin-dependent monooxygenases. Protein Sci 2020; 28:8-29. [PMID: 30311986 DOI: 10.1002/pro.3525] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/08/2018] [Accepted: 10/08/2018] [Indexed: 12/12/2022]
Abstract
Many flavoenzymes catalyze hydroxylation of aromatic compounds especially phenolic compounds have been isolated and characterized. These enzymes can be classified as either single-component or two-component flavin-dependent hydroxylases (monooxygenases). The hydroxylation reactions catalyzed by the enzymes in this group are useful for modifying the biological properties of phenolic compounds. This review aims to provide an in-depth discussion of the current mechanistic understanding of representative flavin-dependent monooxygenases including 3-hydroxy-benzoate 4-hydroxylase (PHBH, a single-component hydroxylase), 3-hydroxyphenylacetate 4-hydroxylase (HPAH, a two-component hydroxylase), and other monooxygenases which catalyze reactions in addition to hydroxylation, including 2-methyl-3-hydroxypyridine-5-carboxylate oxygenase (MHPCO, a single-component enzyme that catalyzes aromatic-ring cleavage), and HadA monooxygenase (a two-component enzyme that catalyzes additional group elimination reaction). These enzymes have different unique structural features which dictate their reactivity toward various substrates and influence their ability to stabilize flavin intermediates such as C4a-hydroperoxyflavin. Understanding the key catalytic residues and the active site environments important for governing enzyme reactivity will undoubtedly facilitate future work in enzyme engineering or enzyme redesign for the development of biocatalytic methods for the synthesis of valuable compounds.
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Affiliation(s)
- Pirom Chenprakhon
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom, 73170, Thailand
| | - Thanyaporn Wongnate
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand.,Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, 14000, Thailand
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22
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Deng Y, Faivre B, Back O, Lombard M, Pecqueur L, Fontecave M. Structural and Functional Characterization of 4-Hydroxyphenylacetate 3-Hydroxylase from Escherichia coli. Chembiochem 2020; 21:163-170. [PMID: 31155821 DOI: 10.1002/cbic.201900277] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Indexed: 11/08/2022]
Abstract
The hydroxylation of phenols into polyphenols, which are valuable chemicals and pharmaceutical products, is a challenging reaction. The search for green synthetic processes has led to considering microorganisms and pure hydroxylases as catalysts for phenol hydroxylation. Herein, we report the structural and functional characterization of the flavin adenine dinucleotide (FAD)-dependent 4-hydroxyphenylacetate 3-monooxygenase from Escherichia coli, named HpaB. It is shown that this enzyme enjoys a relatively broad substrate specificity, which allows the conversion of a number of non-natural phenolic compounds, such as tyrosol, hydroxymandelic acid, coumaric acid, hydroxybenzoic acid and its methyl ester, and phenol, into the corresponding catechols. The reaction can be performed by using a simple chemical assay based on formate as the electron donor and the organometallic complex [Rh(bpy)Cp*(H2 O)]2+ (Cp*: 1,2,3,4,5-pentamethylcyclopentadiene, bpy: 2,2'-bipyridyl) as the catalyst for FAD reduction. The availability of a crystal structure of HpaB in complex with FAD at 1.8 Å resolution opens up the possibility of the rational tuning of the substrate specificity and activity of this interesting class of phenol hydroxylases.
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Affiliation(s)
- Yifan Deng
- Laboratoire de Chimie des Processus Biologiques, Collège de France, Sorbonne Université, CNRS, UMR 8229, PSL Research University, 11 place Marcelin Berthelot, 75005, Paris, France
| | - Bruno Faivre
- Laboratoire de Chimie des Processus Biologiques, Collège de France, Sorbonne Université, CNRS, UMR 8229, PSL Research University, 11 place Marcelin Berthelot, 75005, Paris, France
| | - Olivier Back
- Solvay, Research and Innovation Center of Lyon, 85, Avenue des frères Perret, 69190, Saint-Fons, France
| | - Murielle Lombard
- Laboratoire de Chimie des Processus Biologiques, Collège de France, Sorbonne Université, CNRS, UMR 8229, PSL Research University, 11 place Marcelin Berthelot, 75005, Paris, France
| | - Ludovic Pecqueur
- Laboratoire de Chimie des Processus Biologiques, Collège de France, Sorbonne Université, CNRS, UMR 8229, PSL Research University, 11 place Marcelin Berthelot, 75005, Paris, France
| | - Marc Fontecave
- Laboratoire de Chimie des Processus Biologiques, Collège de France, Sorbonne Université, CNRS, UMR 8229, PSL Research University, 11 place Marcelin Berthelot, 75005, Paris, France
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Levy-Booth DJ, Fetherolf MM, Stewart GR, Liu J, Eltis LD, Mohn WW. Catabolism of Alkylphenols in Rhodococcus via a Meta-Cleavage Pathway Associated With Genomic Islands. Front Microbiol 2019; 10:1862. [PMID: 31481940 PMCID: PMC6710988 DOI: 10.3389/fmicb.2019.01862] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 07/29/2019] [Indexed: 01/01/2023] Open
Abstract
The bacterial catabolism of aromatic compounds has considerable promise to convert lignin depolymerization products to commercial chemicals. Alkylphenols are a key class of depolymerization products whose catabolism is not well-elucidated. We isolated Rhodococcus rhodochrous EP4 on 4-ethylphenol and applied genomic and transcriptomic approaches to elucidate alkylphenol catabolism in EP4 and Rhodococcus jostii RHA1. RNA-Seq and RT-qPCR revealed a pathway encoded by the aphABCDEFGHIQRS genes that degrades 4-ethylphenol via the meta-cleavage of 4-ethylcatechol. This process was initiated by a two-component alkylphenol hydroxylase, encoded by the aphAB genes, which were upregulated ~3,000-fold. Purified AphAB from EP4 had highest specific activity for 4-ethylphenol and 4-propylphenol (~2,000 U/mg) but did not detectably transform phenol. Nevertheless, a ΔaphA mutant in RHA1 grew on 4-ethylphenol by compensatory upregulation of phenol hydroxylase genes (pheA1-3). Deletion of aphC, encoding an extradiol dioxygenase, prevented growth on 4-alkylphenols but not phenol. Disruption of pcaL in the β-ketoadipate pathway prevented growth on phenol but not 4-alkylphenols. Thus, 4-alkylphenols are catabolized exclusively via meta-cleavage in rhodococci while phenol is subject to ortho-cleavage. A putative genomic island encoding aph genes was identified in EP4 and several other rhodococci. Overall, this study identifies a 4-alkylphenol pathway in rhodococci, demonstrates key enzymes involved, and presents evidence that the pathway is encoded in a genomic island. These advances are of particular importance for wide-ranging industrial applications of rhodococci, including upgrading of lignocellulose biomass.
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Affiliation(s)
- David J Levy-Booth
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Morgan M Fetherolf
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Gordon R Stewart
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Jie Liu
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - Lindsay D Eltis
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
| | - William W Mohn
- Department of Microbiology and Immunology, Life Sciences Institute, The University of British Columbia, Vancouver, BC, Canada
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25
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Structural Insights into Catalytic Versatility of the Flavin-dependent Hydroxylase (HpaB) from Escherichia coli. Sci Rep 2019; 9:7087. [PMID: 31068633 PMCID: PMC6506529 DOI: 10.1038/s41598-019-43577-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Accepted: 04/27/2019] [Indexed: 01/07/2023] Open
Abstract
4-Hydroxyphenylacetate 3-hydroxylase (EcHpaB) from Escherichia coli is capable of efficient ortho-hydroxylation of a wide range of phenolic compounds and demonstrates great potential for broad chemoenzymatic applications. To understand the structural and mechanistic basis of its catalytic versatility, we elucidated the crystal structure of EcHpaB by X-ray crystallography, which revealed a unique loop structure covering the active site. We further performed mutagenesis studies of this loop to probe its role in substrate specificity and catalytic activity. Our results not only showed the loop has great plasticity and strong tolerance towards extensive mutagenesis, but also suggested a flexible loop that enables the entrance and stable binding of substrates into the active site is the key factor to the enzyme catalytic versatility. These findings lay the groundwork for editing the loop sequence and structure for generation of EcHpaB mutants with improved performance for broader laboratory and industrial use.
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26
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Chen W, Yao J, Meng J, Han W, Tao Y, Chen Y, Guo Y, Shi G, He Y, Jin JM, Tang SY. Promiscuous enzymatic activity-aided multiple-pathway network design for metabolic flux rearrangement in hydroxytyrosol biosynthesis. Nat Commun 2019; 10:960. [PMID: 30814511 PMCID: PMC6393456 DOI: 10.1038/s41467-019-08781-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 01/11/2019] [Indexed: 12/04/2022] Open
Abstract
Genetic diversity is a result of evolution, enabling multiple ways for one particular physiological activity. Here, we introduce this strategy into bioengineering. We design two hydroxytyrosol biosynthetic pathways using tyrosine as substrate. We show that the synthetic capacity is significantly improved when two pathways work simultaneously comparing to each individual pathway. Next, we engineer flavin-dependent monooxygenase HpaBC for tyrosol hydroxylase, tyramine hydroxylase, and promiscuous hydroxylase active on both tyrosol and tyramine using directed divergent evolution strategy. Then, the mutant HpaBCs are employed to catalyze two missing steps in the hydroxytyrosol biosynthetic pathways designed above. Our results demonstrate that the promiscuous tyrosol/tyramine hydroxylase can minimize the cell metabolic burden induced by protein overexpression and allow the biosynthetic carbon flow to be divided between two pathways. Thus, the efficiency of the hydroxytyrosol biosynthesis is significantly improved by rearranging the metabolic flux among multiple pathways.
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Affiliation(s)
- Wei Chen
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Jun Yao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jie Meng
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Wenjing Han
- Beijing Key Laboratory of Plant Resources Research and Development, Beijing Technology and Business University, Beijing, China
| | - Yong Tao
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yihua Chen
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yixin Guo
- Center for Drug Discovery & Technology Development of Yunnan Traditional Medicine, Yunnan Provincial Academy of Science and Technology, Kunming, China
| | - Guizhi Shi
- University of Chinese Academy of Sciences, Beijing, China
| | - Yang He
- Life Science Institute, Zhejiang University, Hangzhou, China.
| | - Jian-Ming Jin
- Beijing Key Laboratory of Plant Resources Research and Development, Beijing Technology and Business University, Beijing, China.
| | - Shuang-Yan Tang
- CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
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27
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Hashimoto T, Nozawa D, Mukai K, Matsuyama A, Kuramochi K, Furuya T. Monooxygenase-catalyzed regioselective hydroxylation for the synthesis of hydroxyequols. RSC Adv 2019; 9:21826-21830. [PMID: 35518870 PMCID: PMC9066559 DOI: 10.1039/c9ra03913a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 07/09/2019] [Indexed: 11/21/2022] Open
Abstract
A one-step product-selective approach for synthesizing hydroxyequols from equol using oxidation biocatalysts was developed.
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Affiliation(s)
- Takafumi Hashimoto
- Department of Applied Biological Science
- Faculty of Science and Technology
- Tokyo University of Science
- Noda
- Japan
| | - Daiki Nozawa
- Department of Applied Biological Science
- Faculty of Science and Technology
- Tokyo University of Science
- Noda
- Japan
| | | | | | - Kouji Kuramochi
- Department of Applied Biological Science
- Faculty of Science and Technology
- Tokyo University of Science
- Noda
- Japan
| | - Toshiki Furuya
- Department of Applied Biological Science
- Faculty of Science and Technology
- Tokyo University of Science
- Noda
- Japan
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28
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Pimviriyakul P, Surawatanawong P, Chaiyen P. Oxidative dehalogenation and denitration by a flavin-dependent monooxygenase is controlled by substrate deprotonation. Chem Sci 2018; 9:7468-7482. [PMID: 30319747 PMCID: PMC6180312 DOI: 10.1039/c8sc01482e] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 08/08/2018] [Indexed: 12/19/2022] Open
Abstract
Enzymes that are capable of detoxifying halogenated phenols (HPs) and nitrophenols (NPs) are valuable for bioremediation and waste biorefining. HadA monooxygenase was found to perform dual functions of oxidative dehalogenation (hydroxylation plus halide elimination) and denitration (hydroxylation plus nitro elimination). Rate constants associated with individual steps of HadA reactions with phenol, halogenated phenols and nitrophenols were measured using combined transient kinetic approaches of stopped-flow absorbance/fluorescence and rapid-quench flow techniques. Density functional theory was used to calculate the thermodynamic and electronic parameters associated with hydroxylation and group elimination steps. These parameters were correlated with the rate constants of hydroxylation, group elimination, and overall product formation to identify factors controlling individual steps. The results indicated that the hydroxylation rate constant is higher when the pK a of the phenolic group is lower, i.e. it is more easily deprotonated, but not higher when the energy gap between the E LUMO of the C4a-hydroperoxy-FAD intermediate and the E HOMO of the phenolate substrate is lower. These data suggest that the substrate deprotonation has a higher energy barrier than the -OH transfer, and thus controls the hydroxylation step. For the group elimination, the process is controlled by the ability of the C-X bond to break. For the overall product formation (hydroxylation and group elimination combined), this analysis showed that the rate constant of product formation is dependent on the pK a value of the substrate, indicating that the overall reaction is controlled by substrate deprotonation. This step also likely has the highest energy barrier and thus controls the overall process of oxidative dehalogenation and denitration by HadA. This report is the first to identify a key mechanistic factor controlling the enzymatic processes of oxidative dehalogenation and denitration.
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Affiliation(s)
- Panu Pimviriyakul
- School of Biomolecular Science and Engineering , Vidyasirimedhi Institute of Science and Technology (VISTEC) , Wangchan Valley , Rayong , 21210 , Thailand .
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology , Faculty of Science , Mahidol University , Bangkok , 10400 , Thailand
| | - Panida Surawatanawong
- Department of Chemistry and Center of Excellence for Innovation in Chemistry , Faculty of Science , Mahidol University , Bangkok , 10400 , Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering , Vidyasirimedhi Institute of Science and Technology (VISTEC) , Wangchan Valley , Rayong , 21210 , Thailand .
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29
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Heine T, van Berkel WJH, Gassner G, van Pée KH, Tischler D. Two-Component FAD-Dependent Monooxygenases: Current Knowledge and Biotechnological Opportunities. BIOLOGY 2018; 7:biology7030042. [PMID: 30072664 PMCID: PMC6165268 DOI: 10.3390/biology7030042] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 07/31/2018] [Accepted: 08/01/2018] [Indexed: 12/11/2022]
Abstract
Flavoprotein monooxygenases create valuable compounds that are of high interest for the chemical, pharmaceutical, and agrochemical industries, among others. Monooxygenases that use flavin as cofactor are either single- or two-component systems. Here we summarize the current knowledge about two-component flavin adenine dinucleotide (FAD)-dependent monooxygenases and describe their biotechnological relevance. Two-component FAD-dependent monooxygenases catalyze hydroxylation, epoxidation, and halogenation reactions and are physiologically involved in amino acid metabolism, mineralization of aromatic compounds, and biosynthesis of secondary metabolites. The monooxygenase component of these enzymes is strictly dependent on reduced FAD, which is supplied by the reductase component. More and more representatives of two-component FAD-dependent monooxygenases have been discovered and characterized in recent years, which has resulted in the identification of novel physiological roles, functional properties, and a variety of biocatalytic opportunities.
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Affiliation(s)
- Thomas Heine
- Institute of Biosciences, Environmental Microbiology, TU Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany.
| | - Willem J H van Berkel
- Laboratory of Biochemistry, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - George Gassner
- Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA.
| | - Karl-Heinz van Pée
- Allgemeine Biochemie, Technische Universität Dresden, 01062 Dresden, Germany.
| | - Dirk Tischler
- Institute of Biosciences, Environmental Microbiology, TU Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany.
- Microbial Biotechnology, Ruhr University Bochum, Universitätsstr. 150, 44780 Bochum, Germany.
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30
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Yuenyao A, Petchyam N, Kamonsutthipaijit N, Chaiyen P, Pakotiprapha D. Crystal structure of the flavin reductase of Acinetobacter baumannii p-hydroxyphenylacetate 3-hydroxylase (HPAH) and identification of amino acid residues underlying its regulation by aromatic ligands. Arch Biochem Biophys 2018; 653:24-38. [PMID: 29940152 DOI: 10.1016/j.abb.2018.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/07/2018] [Accepted: 06/21/2018] [Indexed: 10/28/2022]
Abstract
The first step in the degradation of p-hydroxyphenylacetic acid (HPA) is catalyzed by the two-component enzyme p-hydroxyphenylacetate 3-hydroxylase (HPAH). The two components of Acinetobacter baumannii HPAH are known as C1 and C2, respectively. C1 is a flavin reductase that uses NADH to generate reduced flavin mononucleotide (FMNH-), which is used by C2 in the hydroxylation of HPA. Interestingly, although HPA is not directly involved in the reaction catalyzed by C1, the presence of HPA dramatically increases the FMN reduction rate. Amino acid sequence analysis revealed that C1 contains two domains: an N-terminal flavin reductase domain, and a C-terminal MarR domain. Although MarR proteins typically function as transcription regulators, the MarR domain of C1 was found to play an auto-inhibitory role. Here, we report a crystal structure of C1 and small-angle X-ray scattering (SAXS) studies that revealed that C1 undergoes a substantial conformational change in the presence of HPA, concomitant with the increase in the rate of flavin reduction. Amino acid residues that are important for HPA binding and regulation of C1 activity were identified by site-directed mutagenesis. Amino acid sequence similarity analysis revealed several as yet uncharacterized flavin reductases with N- or C-terminal fusions.
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Affiliation(s)
- Anan Yuenyao
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Nopphon Petchyam
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | | | - Pimchai Chaiyen
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology Faculty of Science, Mahidol University, Bangkok, 10400, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Danaya Pakotiprapha
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology Faculty of Science, Mahidol University, Bangkok, 10400, Thailand.
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31
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Hino T, Hamamoto H, Suzuki H, Yagi H, Ohshiro T, Nagano S. Crystal structures of TdsC, a dibenzothiophene monooxygenase from the thermophile Paenibacillus sp. A11-2, reveal potential for expanding its substrate selectivity. J Biol Chem 2017; 292:15804-15813. [PMID: 28768765 DOI: 10.1074/jbc.m117.788513] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/23/2017] [Indexed: 11/06/2022] Open
Abstract
Sulfur compounds in fossil fuels are a major source of environmental pollution, and microbial desulfurization has emerged as a promising technology for removing sulfur under mild conditions. The enzyme TdsC from the thermophile Paenibacillus sp. A11-2 is a two-component flavin-dependent monooxygenase that catalyzes the oxygenation of dibenzothiophene (DBT) to its sulfoxide (DBTO) and sulfone (DBTO2) during microbial desulfurization. The crystal structures of the apo and flavin mononucleotide (FMN)-bound forms of DszC, an ortholog of TdsC, were previously determined, although the structure of the ternary substrate-FMN-enzyme complex remains unknown. Herein, we report the crystal structures of the DBT-FMN-TdsC and DBTO-FMN-TdsC complexes. These ternary structures revealed many hydrophobic and hydrogen-bonding interactions with the substrate, and the position of the substrate could reasonably explain the two-step oxygenation of DBT by TdsC. We also determined the crystal structure of the indole-bound enzyme because TdsC, but not DszC, can also oxidize indole, and we observed that indole binding did not induce global conformational changes in TdsC with or without bound FMN. We also found that the two loop regions close to the FMN-binding site are disordered in apo-TdsC and become structured upon FMN binding. Alanine substitutions of Tyr-93 and His-388, which are located close to the substrate and FMN bound to TdsC, significantly decreased benzothiophene oxygenation activity, suggesting their involvement in supplying protons to the active site. Interestingly, these substitutions increased DBT oxygenation activity by TdsC, indicating that expanding the substrate-binding site can increase the oxygenation activity of TdsC on larger sulfur-containing substrates, a property that should prove useful for future microbial desulfurization applications.
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Affiliation(s)
- Tomoya Hino
- From the Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8552, Japan
| | - Haruka Hamamoto
- From the Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8552, Japan
| | - Hirokazu Suzuki
- From the Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8552, Japan
| | - Hisashi Yagi
- From the Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8552, Japan
| | - Takashi Ohshiro
- From the Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8552, Japan
| | - Shingo Nagano
- From the Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyamacho-minami, Tottori 680-8552, Japan
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32
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Kugel S, Baunach M, Baer P, Ishida-Ito M, Sundaram S, Xu Z, Groll M, Hertweck C. Cryptic indole hydroxylation by a non-canonical terpenoid cyclase parallels bacterial xenobiotic detoxification. Nat Commun 2017. [PMID: 28643772 PMCID: PMC5481743 DOI: 10.1038/ncomms15804] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Terpenoid natural products comprise a wide range of molecular architectures that typically result from C–C bond formations catalysed by classical type I/II terpene cyclases. However, the molecular diversity of biologically active terpenoids is substantially increased by fully unrelated, non-canonical terpenoid cyclases. Their evolutionary origin has remained enigmatic. Here we report the in vitro reconstitution of an unusual flavin-dependent bacterial indoloterpenoid cyclase, XiaF, together with a designated flavoenzyme-reductase (XiaP) that mediates a key step in xiamycin biosynthesis. The crystal structure of XiaF with bound FADH2 (at 2.4 Å resolution) and phylogenetic analyses reveal that XiaF is, surprisingly, most closely related to xenobiotic-degrading enzymes. Biotransformation assays show that XiaF is a designated indole hydroxylase that can be used for the production of indigo and indirubin. We unveil a cryptic hydroxylation step that sets the basis for terpenoid cyclization and suggest that the cyclase has evolved from xenobiotics detoxification enzymes. The biosynthesis of xiamycin, an antimicrobial bacterial indolosesquiterpenoid, involves an unusual cyclization cascade. Here, the authors characterise the XiaF enzyme, which resembles xenobiont-degrading enzymes and is responsible for a hidden indole hydroxylation step that triggers the cyclization reaction.
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Affiliation(s)
- Susann Kugel
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, 07745 Jena, Germany
| | - Martin Baunach
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, 07745 Jena, Germany
| | - Philipp Baer
- Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Mie Ishida-Ito
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, 07745 Jena, Germany
| | - Srividhya Sundaram
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, 07745 Jena, Germany
| | - Zhongli Xu
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, 07745 Jena, Germany
| | - Michael Groll
- Center for Integrated Protein Science Munich (CIPSM), Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85748 Garching, Germany
| | - Christian Hertweck
- Department of Biomolecular Chemistry, Leibniz Institute for Natural Product Research and Infection Biology (HKI), Beutenbergstr. 11a, 07745 Jena, Germany.,Natural Product Chemistry, Friedrich Schiller University, 07743 Jena, Germany
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33
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Chenprakhon P, Dhammaraj T, Chantiwas R, Chaiyen P. Hydroxylation of 4-hydroxyphenylethylamine derivatives by R263 variants of the oxygenase component of p -hydroxyphenylacetate-3-hydroxylase. Arch Biochem Biophys 2017; 620:1-11. [DOI: 10.1016/j.abb.2017.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 11/29/2022]
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34
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Pan G, Gao X, Fan K, Liu J, Meng B, Gao J, Wang B, Zhang C, Han H, Ai G, Chen Y, Wu D, Liu ZJ, Yang K. Structure and Function of a C-C Bond Cleaving Oxygenase in Atypical Angucycline Biosynthesis. ACS Chem Biol 2017; 12:142-152. [PMID: 28103689 DOI: 10.1021/acschembio.6b00621] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
C-C bond ring cleaving oxygenases represent a unique family of enzymes involved in the B ring cleavage reaction only observed in atypical angucycline biosynthesis. B ring cleavage is the key reaction leading to dramatic divergence in the final structures of atypical angucyclines. Here, we present the crystal structure of AlpJ, the first structure of this family of enzymes. AlpJ has been verified as the enzyme catalyzing C-C bond cleavage in kinamycin biosynthesis. The crystal structure of the AlpJ monomer resembles the dimeric structure of ferredoxin-like proteins. The N- and C-terminal halves of AlpJ are homologous, and both contain a putative hydrophobic substrate binding pocket in the "closed" and "open" conformations, respectively. Structural comparison of AlpJ with ActVA-Orf6 and protein-ligand docking analysis suggest that the residues including Asn60, Trp64, and Trp181 are possibly involved in substrate recognition. Site-directed mutagenesis results supported our hypothesis, as mutation of these residues led to nearly a complete loss of the activity of AlpJ. Structural analysis also revealed that AlpJ possesses an intramolecular domain-domain interface, where the residues His50 and Tyr178 form a hydrogen bond that probably stabilizes the three-dimensional structure of AlpJ. Site-directed mutagenesis showed that the two residues, His50 and Tyr178, were vital for the activity of AlpJ. Our findings shed light on the structure and catalytic mechanism of the AlpJ family of oxygenases, which presumably involves two active sites that might function in a cooperative manner.
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Affiliation(s)
- Guohui Pan
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Xiaoqin Gao
- National
Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Keqiang Fan
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Junlin Liu
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, People’s Republic of China
| | - Bing Meng
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, People’s Republic of China
| | - Jinmin Gao
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Bin Wang
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Chaobo Zhang
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
- University of Chinese Academy of Sciences, Beijing 100049, People’s Republic of China
| | - Hui Han
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Guomin Ai
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Yihua Chen
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Dong Wu
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, People’s Republic of China
| | - Zhi-Jie Liu
- National
Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
- Institute
of Molecular and Clinical Medicine, Kunming Medical University, Kunming 650500, China
| | - Keqian Yang
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
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35
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Chang CY, Lohman JR, Cao H, Tan K, Rudolf JD, Ma M, Xu W, Bingman CA, Yennamalli RM, Bigelow L, Babnigg G, Yan X, Joachimiak A, Phillips GN, Shen B. Crystal Structures of SgcE6 and SgcC, the Two-Component Monooxygenase That Catalyzes Hydroxylation of a Carrier Protein-Tethered Substrate during the Biosynthesis of the Enediyne Antitumor Antibiotic C-1027 in Streptomyces globisporus. Biochemistry 2016; 55:5142-54. [PMID: 27560143 PMCID: PMC5024704 DOI: 10.1021/acs.biochem.6b00713] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
C-1027
is a chromoprotein enediyne antitumor antibiotic produced
by Streptomyces globisporus. In the last step of
biosynthesis of the (S)-3-chloro-5-hydroxy-β-tyrosine
moiety of the C-1027 enediyne chromophore, SgcE6 and SgcC compose
a two-component monooxygenase that hydroxylates the C-5 position of
(S)-3-chloro-β-tyrosine. This two-component
monooxygenase is remarkable for two reasons. (i) SgcE6 specifically
reacts with FAD and NADH, and (ii) SgcC is active with only the peptidyl
carrier protein (PCP)-tethered substrate. To address the molecular
details of substrate specificity, we determined the crystal structures
of SgcE6 and SgcC at 1.66 and 2.63 Å resolution, respectively.
SgcE6 shares a similar β-barrel fold with the class I HpaC-like
flavin reductases. A flexible loop near the active site of SgcE6 plays
a role in FAD binding, likely by providing sufficient space to accommodate
the AMP moiety of FAD, when compared to that of FMN-utilizing homologues.
SgcC shows structural similarity to a few other known FADH2-dependent monooxygenases and sheds light on some biochemically but
not structurally characterized homologues. The crystal structures
reported here provide insights into substrate specificity, and comparison
with homologues provides a catalytic mechanism of the two-component,
FADH2-dependent monooxygenase (SgcE6 and SgcC) that catalyzes
the hydroxylation of a PCP-tethered substrate.
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Affiliation(s)
- Chin-Yuan Chang
- Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States
| | - Jeremy R Lohman
- Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States
| | - Hongnan Cao
- BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Kemin Tan
- Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Jeffrey D Rudolf
- Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States
| | - Ming Ma
- Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States
| | - Weijun Xu
- BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Craig A Bingman
- Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53705, United States
| | - Ragothaman M Yennamalli
- BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States.,Department of Biotechnology and Bioinformatics, Jaypee University of Information Technology , Waknaghat, Himachal Pradesh, India 173234
| | - Lance Bigelow
- Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Gyorgy Babnigg
- Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - Xiaohui Yan
- Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States
| | - Andrzej Joachimiak
- Midwest Center for Structural Genomics and Structural Biology Center, Biosciences Division, Argonne National Laboratory , Argonne, Illinois 60439, United States
| | - George N Phillips
- BioScience at Rice and Department of Chemistry, Rice University , Houston, Texas 77251, United States
| | - Ben Shen
- Department of Chemistry, The Scripps Research Institute , Jupiter, Florida 33458, United States
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36
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Visitsatthawong S, Chenprakhon P, Chaiyen P, Surawatanawong P. Mechanism of Oxygen Activation in a Flavin-Dependent Monooxygenase: A Nearly Barrierless Formation of C4a-Hydroperoxyflavin via Proton-Coupled Electron Transfer. J Am Chem Soc 2015; 137:9363-74. [DOI: 10.1021/jacs.5b04328] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Surawit Visitsatthawong
- Department
of Chemistry and Center of Excellence for Innovation in
Chemistry, Faculty of Science, †Institute for Innovative Learning, and ∥Department of
Biochemistry and Center of Excellence in Protein Structure and Function,
Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Pirom Chenprakhon
- Department
of Chemistry and Center of Excellence for Innovation in
Chemistry, Faculty of Science, †Institute for Innovative Learning, and ∥Department of
Biochemistry and Center of Excellence in Protein Structure and Function,
Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Pimchai Chaiyen
- Department
of Chemistry and Center of Excellence for Innovation in
Chemistry, Faculty of Science, †Institute for Innovative Learning, and ∥Department of
Biochemistry and Center of Excellence in Protein Structure and Function,
Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Panida Surawatanawong
- Department
of Chemistry and Center of Excellence for Innovation in
Chemistry, Faculty of Science, †Institute for Innovative Learning, and ∥Department of
Biochemistry and Center of Excellence in Protein Structure and Function,
Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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37
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Sucharitakul J, Tinikul R, Chaiyen P. Mechanisms of reduced flavin transfer in the two-component flavin-dependent monooxygenases. Arch Biochem Biophys 2014; 555-556:33-46. [DOI: 10.1016/j.abb.2014.05.009] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 05/10/2014] [Accepted: 05/12/2014] [Indexed: 10/25/2022]
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38
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Lin Y, Yan Y. Biotechnological production of plant-specific hydroxylated phenylpropanoids. Biotechnol Bioeng 2014; 111:1895-9. [DOI: 10.1002/bit.25237] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 01/20/2014] [Accepted: 03/10/2014] [Indexed: 01/07/2023]
Affiliation(s)
- Yuheng Lin
- College of Engineering; University of Georgia; Athens Georgia 30602
| | - Yajun Yan
- BioChemical Engineering Program; College of Engineering; University of Georgia; 601B Driftmier Engineering Center Athens Georgia 30602
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39
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Huang Q, Lin Y, Yan Y. Caffeic acid production enhancement by engineering a phenylalanine over-producing Escherichia coli strain. Biotechnol Bioeng 2013; 110:3188-96. [PMID: 23801069 DOI: 10.1002/bit.24988] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 06/17/2013] [Accepted: 06/18/2013] [Indexed: 11/10/2022]
Abstract
Caffeic acid is a plant-specific phenylpropanoic acid with multiple health-improving effects reported, and its therapeutic derivatives have also been studied throughout the last decade. To meet its market need and achieve high-level production, microbial production of caffeic acid approaches have been developed in metabolically engineered Escherichia coli. In our previous work, we have established the first artificial pathway that realized de novo production of caffeic acid using E. coli endogenous 4-hydroxyphenylacetate 3-hydroxylase (4HP3H). In this work, we exploited the catalytic potential of 4HPA3H in the whole-cell bioconversion study and produced 3.82 g/L (461.12 mg/L/OD) caffeic acid from p-coumaric acid, a direct precursor. We further engineered a phenylalanine over-producer into a tyrosine over-producer and then introduced the artificial pathway. After adjusting the expression strategy and optimizing the inoculants timing, de novo production of caffeic acid reached 766.68 mg/L. Both results from the direct precursor and simple carbon sources represent the highest titers of caffeic acid from microbial production so far.
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Affiliation(s)
- Qin Huang
- College of Engineering, University of Georgia, Athens, Georgia
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40
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Furuya T, Kino K. Catalytic activity of the two-component flavin-dependent monooxygenase from Pseudomonas aeruginosa toward cinnamic acid derivatives. Appl Microbiol Biotechnol 2013; 98:1145-54. [PMID: 23666444 DOI: 10.1007/s00253-013-4958-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 04/24/2013] [Accepted: 04/26/2013] [Indexed: 11/28/2022]
Abstract
4-Hydroxyphenylacetate 3-hydroxylases (HPAHs) of the two-component flavin-dependent monooxygenase family are attractive enzymes that possess the catalytic potential to synthesize valuable ortho-diphenol compounds from simple monophenol compounds. In this study, we investigated the catalytic activity of HPAH from Pseudomonas aeruginosa strain PAO1 toward cinnamic acid derivatives. We prepared Escherichia coli cells expressing the hpaB gene encoding the monooxygenase component and the hpaC gene encoding the oxidoreductase component. E. coli cells expressing HpaBC exhibited no or very low oxidation activity toward cinnamic acid, o-coumaric acid, and m-coumaric acid, whereas they rapidly oxidized p-coumaric acid to caffeic acid. Interestingly, after p-coumaric acid was almost completely consumed, the resulting caffeic acid was further oxidized to 3,4,5-trihydroxycinnamic acid. In addition, HpaBC exhibited oxidation activity toward 3-(4-hydroxyphenyl)propanoic acid, ferulic acid, and coniferaldehyde to produce the corresponding ortho-diphenols. We also investigated a flask-scale production of caffeic acid from p-coumaric acid as the model reaction for HpaBC-catalyzed syntheses of hydroxycinnamic acids. Since the initial concentrations of the substrate p-coumaric acid higher than 40 mM markedly inhibited its HpaBC-catalyzed oxidation, the reaction was carried out by repeatedly adding 20 mM of this substrate to the reaction mixture. Furthermore, by using the HpaBC whole-cell catalyst in the presence of glycerol, our experimental setup achieved the high-yield production of caffeic acid, i.e., 56.6 mM (10.2 g/L) within 24 h. These catalytic activities of HpaBC will provide an easy and environment-friendly synthetic approach to hydroxycinnamic acids.
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Affiliation(s)
- Toshiki Furuya
- Department of Applied Chemistry, Faculty of Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku-ku, Tokyo, 169-8555, Japan,
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41
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Chaiyen P, Fraaije MW, Mattevi A. The enigmatic reaction of flavins with oxygen. Trends Biochem Sci 2012; 37:373-80. [DOI: 10.1016/j.tibs.2012.06.005] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/19/2012] [Accepted: 06/28/2012] [Indexed: 10/28/2022]
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42
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Hayes RP, Webb BN, Subramanian AK, Nissen M, Popchock A, Xun L, Kang C. Structural and catalytic differences between two FADH(2)-dependent monooxygenases: 2,4,5-TCP 4-monooxygenase (TftD) from Burkholderia cepacia AC1100 and 2,4,6-TCP 4-monooxygenase (TcpA) from Cupriavidus necator JMP134. Int J Mol Sci 2012; 13:9769-9784. [PMID: 22949829 PMCID: PMC3431827 DOI: 10.3390/ijms13089769] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/27/2012] [Accepted: 07/31/2012] [Indexed: 11/16/2022] Open
Abstract
2,4,5-TCP 4-monooxygenase (TftD) and 2,4,6-TCP 4-monooxygenase (TcpA) have been discovered in the biodegradation of 2,4,5-trichlorophenol (2,4,5-TCP) and 2,4,6-trichlorophenol (2,4,6-TCP). TcpA and TftD belong to the reduced flavin adenine dinucleotide (FADH2)-dependent monooxygenases and both use 2,4,6-TCP as a substrate; however, the two enzymes produce different end products. TftD catalyzes a typical monooxygenase reaction, while TcpA catalyzes a typical monooxygenase reaction followed by a hydrolytic dechlorination. We have previously reported the 3D structure of TftD and confirmed the catalytic residue, His289. Here we have determined the crystal structure of TcpA and investigated the apparent differences in specificity and catalysis between these two closely related monooxygenases through structural comparison. Our computational docking results suggest that Ala293 in TcpA (Ile292 in TftD) is possibly responsible for the differences in substrate specificity between the two monooxygenases. We have also identified that Arg101 in TcpA could provide inductive effects/charge stabilization during hydrolytic dechlorination. The collective information provides a fundamental understanding of the catalytic reaction mechanism and the parameters for substrate specificity. The information may provide guidance for designing bioremediation strategies for polychlorophenols, a major group of environmental pollutants.
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Affiliation(s)
- Robert P. Hayes
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; E-Mails: (R.P.H.); (B.N.W.); (A.K.S.); (M.N.)
| | - Brian N. Webb
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; E-Mails: (R.P.H.); (B.N.W.); (A.K.S.); (M.N.)
| | - Arun Kumar Subramanian
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; E-Mails: (R.P.H.); (B.N.W.); (A.K.S.); (M.N.)
| | - Mark Nissen
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; E-Mails: (R.P.H.); (B.N.W.); (A.K.S.); (M.N.)
| | - Andrew Popchock
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA; E-Mail:
| | - Luying Xun
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (L.X.); (C.K.); Tel.: +1-509-335-2787 (L.X.); +1-509-335-1523 (C.K.); Fax: +1-509-335-9688 (L.X.); +1-509-335-8867 (C.K.)
| | - ChulHee Kang
- Department of Chemistry, Washington State University, Pullman, WA 99164, USA; E-Mails: (R.P.H.); (B.N.W.); (A.K.S.); (M.N.)
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (L.X.); (C.K.); Tel.: +1-509-335-2787 (L.X.); +1-509-335-1523 (C.K.); Fax: +1-509-335-9688 (L.X.); +1-509-335-8867 (C.K.)
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43
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Phongsak T, Sucharitakul J, Thotsaporn K, Oonanant W, Yuvaniyama J, Svasti J, Ballou DP, Chaiyen P. The C-terminal domain of 4-hydroxyphenylacetate 3-hydroxylase from Acinetobacter baumannii is an autoinhibitory domain. J Biol Chem 2012; 287:26213-22. [PMID: 22661720 DOI: 10.1074/jbc.m112.354472] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p-Hydroxyphenylacetate (HPA) 3-hydroxylase from Acinetobacter baumannii consists of a reductase component (C(1)) and an oxygenase component (C(2)). C(1) catalyzes the reduction of FMN by NADH to provide FMNH(-) as a substrate for C(2). The rate of reduction of flavin is enhanced ∼20-fold by binding HPA. The N-terminal domain of C(1) is homologous to other flavin reductases, whereas the C-terminal domain (residues 192-315) is similar to MarR, a repressor protein involved in bacterial antibiotic resistance. In this study, three forms of truncated C(1) variants and single site mutation variants of residues Arg-21, Phe-216, Arg-217, Ile-246, and Arg-247 were constructed to investigate the role of the C-terminal domain in regulating C(1). In the absence of HPA, the C(1) variant in which residues 179-315 were removed (t178C(1)) was reduced by NADH and released FMNH(-) at the same rates as wild-type enzyme carries out these functions in the presence of HPA. In contrast, variants with residues 231-315 removed behaved similarly to the wild-type enzyme. Thus, residues 179-230 are involved in repressing the production of FMNH(-) in the absence of HPA. These results are consistent with the C-terminal domain in the wild-type enzyme being an autoinhibitory domain that upon binding the effector HPA undergoes conformational changes to allow faster flavin reduction and release. Most of the single site variants investigated had catalytic properties similar to those of the wild-type enzyme except for the F216A variant, which had a rate of reduction that was not stimulated by HPA. F216A could be involved with HPA binding or in the required conformational change for stimulation of flavin reduction by HPA.
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Affiliation(s)
- Thanawat Phongsak
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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44
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Tongsook C, Sucharitakul J, Thotsaporn K, Chaiyen P. Interactions with the substrate phenolic group are essential for hydroxylation by the oxygenase component of p-hydroxyphenylacetate 3-hydroxylase. J Biol Chem 2011; 286:44491-502. [PMID: 22052902 DOI: 10.1074/jbc.m111.284463] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
p-Hydroxyphenylacetate (HPA) 3-hydroxylase is a two-component flavoprotein monooxygenase that catalyzes the hydroxylation of p-hydroxyphenylacetate to form 3,4-dihydroxyphenylacetate. Based on structures of the oxygenase component (C(2)), both His-120 and Ser-146 are located ~2.8 Å from the hydroxyl group of HPA. The variants H120N, H120Q, H120Y, H120D, and H120E can form C4a-hydroperoxy-FMN (a reactive intermediate necessary for hydroxylation) but cannot hydroxylate HPA. The impairment of H120N is not due to substrate binding because the variant can still bind HPA. In contrast, the H120K variant catalyzes hydroxylation with efficiency comparable with that of the wild-type enzyme; the hydroxylation rate constant for H120K is 5.7 ± 0.6 s(-1), and the product conversion ratio is 75%, compared with values of 16 s(-1) and 90% for the wild-type enzyme. H120R can also catalyze hydroxylation, suggesting that a positive charge on residue 120 can substitute for the hydroxylation function of His-120. Because the hydroxylation reaction of wild-type C(2) is pH-independent between pH 6 and 10, the protonation status of key components required for hydroxylation likely remains unchanged in this pH range. His-120 may be positively charged for selective binding to the phenolate form of HPA, i.e. to form the His(δ+)·HPA(δ-) complex, which in turn promotes oxygen atom transfer via an electrophilic aromatic substitution mechanism. Analysis of Ser-146 variants revealed that this residue is necessary for but not directly engaged in hydroxylation. Product formation in S146A is pH-independent and constant at ~70% over a pH range of 6-10, whereas product formation for S146C decreased from ~65% at pH 6.0 to 27% at pH 10.0. These data indicate that the ionization of Cys-146 in the S146C variant has an adverse effect on hydroxylation, possibly by perturbing formation of the His(δ+)·HPA(δ-) complex needed for hydroxylation.
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Affiliation(s)
- Chanakan Tongsook
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
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45
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Ida K, Suguro M, Suzuki H. High resolution X-ray crystal structures of l-phenylalanine oxidase (deaminating and decarboxylating) from Pseudomonas sp. P-501. Structures of the enzyme-ligand complex and catalytic mechanism. ACTA ACUST UNITED AC 2011; 150:659-69. [DOI: 10.1093/jb/mvr103] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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46
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Thotsaporn K, Chenprakhon P, Sucharitakul J, Mattevi A, Chaiyen P. Stabilization of C4a-hydroperoxyflavin in a two-component flavin-dependent monooxygenase is achieved through interactions at flavin N5 and C4a atoms. J Biol Chem 2011; 286:28170-80. [PMID: 21680741 DOI: 10.1074/jbc.m111.241836] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
p-Hydroxyphenylacetate (HPA) 3-hydroxylase is a two-component flavin-dependent monooxygenase. Based on the crystal structure of the oxygenase component (C(2)), His-396 is 4.5 Å from the flavin C4a locus, whereas Ser-171 is 2.9 Å from the flavin N5 locus. We investigated the roles of these two residues in the stability of the C4a-hydroperoxy-FMN intermediate. The results indicated that the rate constant for C4a-hydroperoxy-FMN formation decreased ~30-fold in H396N, 100-fold in H396A, and 300-fold in the H396V mutant, compared with the wild-type enzyme. Lesser effects of the mutations were found for the subsequent step of H(2)O(2) elimination. Studies on pH dependence showed that the rate constant of H(2)O(2) elimination in H396N and H396V increased when pH increased with pK(a) >9.6 and >9.7, respectively, similar to the wild-type enzyme (pK(a) >9.4). These data indicated that His-396 is important for the formation of the C4a-hydroperoxy-FMN intermediate but is not involved in H(2)O(2) elimination. Transient kinetics of the Ser-171 mutants with oxygen showed that the rate constants for the H(2)O(2) elimination in S171A and S171T were ~1400-fold and 8-fold greater than the wild type, respectively. Studies on the pH dependence of S171A with oxygen showed that the rate constant of H(2)O(2) elimination increased with pH rise and exhibited an approximate pK(a) of 8.0. These results indicated that the interaction of the hydroxyl group side chain of Ser-171 and flavin N5 is required for the stabilization of C4a-hydroperoxy-FMN. The double mutant S171A/H396V reacted with oxygen to directly form the oxidized flavin without stabilizing the C4a-hydroperoxy-FMN intermediate, which confirmed the findings based on the single mutation that His-396 was important for formation and Ser-171 for stabilization of the C4a-hydroperoxy-FMN intermediate in C(2).
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Affiliation(s)
- Kittisak Thotsaporn
- Department of Biochemistry and Center of Excellence in Protein Structure & Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
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47
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Vey JL, Al-Mestarihi A, Hu Y, Funk MA, Bachmann BO, Iverson TM. Structure and mechanism of ORF36, an amino sugar oxidizing enzyme in everninomicin biosynthesis . Biochemistry 2010; 49:9306-17. [PMID: 20866105 DOI: 10.1021/bi101336u] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Everninomicin is a highly modified octasaccharide that belongs to the orthosomycin family of antibiotics and possesses potent Gram-positive antibiotic activity, including broad-spectrum efficacy against multidrug resistant enterococci and Staphylococcus aureus. Among its distinctive structural features is a nitro sugar, l-evernitrose, analogues of which decorate a variety of natural products. Recently, we identified a nitrososynthase enzyme encoded by orf36 from Micromonospora carbonacea var. africana that mediates the flavin-dependent double oxidation of synthetically generated thymidine diphosphate (TDP)-l-epi-vancosamine to the corresponding nitroso sugar. Herein, we utilize a five-enzyme in vitro pathway both to verify that ORF36 catalyzes oxidation of biogenic TDP-l-epi-vancosamine and to determine whether ORF36 exhibits catalytic competence for any of its biosynthetic progenitors, which are candidate substrates for nitrososynthases in vivo. Progenitors solely undergo single-oxidation reactions and terminate in the hydroxylamine oxidation state. Performing the in vitro reactions in the presence of (18)O(2) establishes that molecular oxygen, rather than oxygen from water, is incorporated into ORF36-generated intermediates and products and identifies an off-pathway product that correlates with the oxidation product of a progenitor substrate. The 3.15 Å resolution X-ray crystal structure of ORF36 reveals a tetrameric enzyme that shares a fold with acyl-CoA dehydrogenases and class D flavin-containing monooxygenases, including the nitrososynthase KijD3. However, ORF36 and KijD3 have unusually open active sites in comparison to these related enzymes. Taken together, these studies map substrate determinants and allow the proposal of a minimal monooxygenase mechanism for amino sugar oxidation by ORF36.
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Affiliation(s)
- Jessica L Vey
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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48
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Ruangchan N, Tongsook C, Sucharitakul J, Chaiyen P. pH-dependent studies reveal an efficient hydroxylation mechanism of the oxygenase component of p-hydroxyphenylacetate 3-hydroxylase. J Biol Chem 2010; 286:223-33. [PMID: 21030590 DOI: 10.1074/jbc.m110.163881] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
p-Hydroxyphenylacetate (HPA) 3-hydroxylase (HPAH) catalyzes the hydroxylation of HPA at the ortho-position to yield 3,4-dihydroxyphenylacetate. The enzyme is a flavin-dependent two-component monooxygenase that consists of a reductase component and an oxygenase component (C(2)). C(2) catalyzes the hydroxylation of HPA using oxygen and reduced FMN as co-substrates. To date, the effects of pH on the oxygenation of the two-component monooxygenases have never been reported. Here, we report the reaction kinetics of C(2)·FMNH(-) with oxygen at various pH values investigated by stopped-flow and rapid quenched-flow techniques. In the absence of HPA, the rate constant for the formation of C4a-hydroperoxy-FMN (∼1.1 × 10(6) m(-1)s(-1)) was unaffected at pH 6.2-9.9, which indicated that the pK(a) of the enzyme-bound reduced FMN was less than 6.2. The rate constant for the following H(2)O(2) elimination step increased with higher pH, which is consistent with a pK(a) of >9.4. In the presence of HPA, the rate constants for the formation of C4a-hydroperoxy-FMN (∼4.8 × 10(4) m(-1)s(-1)) and the ensuing hydroxylation step (15-17 s(-1)) were not significantly affected by the pH. In contrast, the following steps of C4a-hydroxy-FMN dehydration to form oxidized FMN occurred through two pathways that were dependent on the pH of the reaction. One pathway, dominant at low pH, allowed the detection of a C4a-hydroxy-FMN intermediate, whereas the pathway dominant at high pH produced oxidized FMN without an apparent accumulation of the intermediate. However, both pathways efficiently catalyzed hydroxylation without generating significant amounts of wasteful H(2)O(2) at pH 6.2-9.9. The decreased accumulation of the intermediate at higher pH was due to the greater rates of C4a-hydroxy-FMN decay caused by the abolishment of substrate inhibition in the dehydration step at high pH.
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Affiliation(s)
- Nantidaporn Ruangchan
- Department of Biochemistry and Center of Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
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Ukaegbu UE, Kantz A, Beaton M, Gassner GT, Rosenzweig AC. Structure and ligand binding properties of the epoxidase component of styrene monooxygenase . Biochemistry 2010; 49:1678-88. [PMID: 20055497 DOI: 10.1021/bi901693u] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Styrene monooxygenase (SMO) is a two-component flavoprotein monooxygenase that transforms styrene to styrene oxide in the first step of the styrene catabolic and detoxification pathway of Pseudomonas putida S12. The crystal structure of the N-terminally histidine-tagged epoxidase component of this system, NSMOA, determined to 2.3 A resolution, indicates the enzyme exists as a homodimer in which each monomer forms two distinct domains. The overall architecture is most similar to that of p-hydroxybenzoate hydroxylase (PHBH), although there are some significant differences in secondary structure. Structural comparisons suggest that a large cavity open to the surface forms the FAD binding site. At the base of this pocket is another cavity that likely represents the styrene binding site. Flavin binding and redox equilibria are tightly coupled such that reduced FAD binds apo NSMOA approximately 8000 times more tightly than the oxidized coenzyme. Equilibrium fluorescence and isothermal titration calorimetry data using benzene as a substrate analogue indicate that the oxidized flavin and substrate analogue binding equilibria of NSMOA are linked such that the binding affinity of each is increased by 60-fold when the enzyme is saturated with the other. A much weaker approximately 2-fold positive cooperative interaction is observed for the linked binding equilibria of benzene and reduced FAD. The low affinity of the substrate analogue for the reduced FAD complex of NSMOA is consistent with a preferred reaction order in which flavin reduction and reaction with oxygen precede the binding of styrene, identifying the apoenzyme structure as the key catalytic resting state of NSMOA poised to bind reduced FAD and initiate the oxygen reaction.
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Affiliation(s)
- Uchechi E Ukaegbu
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208, USA
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Soulimane T, O'Kane SR, Kolaj O. Isolation and purification of Thermus thermophilus HpaB by a crystallization approach. Acta Crystallogr Sect F Struct Biol Cryst Commun 2010; 66:352-6. [PMID: 20208179 PMCID: PMC2833055 DOI: 10.1107/s1744309110003714] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Accepted: 01/29/2010] [Indexed: 05/28/2023]
Abstract
The oxygenase HpaB is a component of the 4-hydroxyphenylacetate 3-monooxygenase enzyme that is responsible for the hydroxylation of 4-hydroxyphenylacetate. It utilizes molecular oxygen and a reduced flavin, which is provided by HpaC, the second component of the enzyme. While isolating integral membrane respiratory complexes from Thermus thermophilus, microcrystals of HpaB were formed. Further purification of the enzyme was achieved by repetitive crystallization. Subsequently, well shaped single crystals of the native enzyme that diffract to 1.82 A resolution were grown in sitting drops. They belong to the orthorhombic space group I222, with unit-cell parameters a = 91.3, b = 99.8, c = 131.7 A.
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Affiliation(s)
- Tewfik Soulimane
- Department of Chemical and Environmental Sciences and Materials and Surface Science Institute, University of Limerick, National Technology Park, Limerick, Ireland.
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