1
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Li Q, Zhang S, Liu F, Su H, Sheng X. Quantum chemical modeling of enantioselective sulfoxidation and epoxidation reactions by indole monooxygenase VpIndA1. Phys Chem Chem Phys 2024; 26:16521-16528. [PMID: 38809594 DOI: 10.1039/d4cp00552j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2024]
Abstract
Indole monooxygenases (IMOs) are enzymes from the family of Group E monooxygenases, requiring flavin adenine dinucleotide (FAD) for their activities. IMOs play important roles in both sulfoxidation and epoxidation reactions. The broad substrate range and high selectivity of IMOs make them promising biocatalytic tools for synthesizing chiral compounds. In the present study, quantum chemical calculations using the cluster approach were performed to investigate the reaction mechanism and the enantioselectivity of the IMO from Variovorax paradoxus EPS (VpIndA1). The sulfoxidation of methyl phenyl sulfide (MPS) and the epoxidation of indene were chosen as the representative reactions. The calculations confirmed that the FADOOH intermediate is the catalytic species in the VpIndA1 reactions. The oxidation of MPS adopts a one-step mechanism involving the direct oxygen-transfer from FADOOH to the substrate and the proton transfer from the -OH group back to FAD, while the oxidation of indene follows a stepwise mechanism involving a carbocation intermediate. It was computationally predicted that VpIndA1 prefers the formation of (S)-product for the MPS sulfoxidation and (1S,2R)-product for the indene epoxidation, consistent with the experimental observations. Importantly, the factors controlling the stereo-preference of the two reactions are identified. The findings in the present study provide valuable insights into the VpIndA1-catalyzed reactions, which are essential for the rational design of this enzyme and other IMOs for industrial applications. It is also worth emphasizing that the quantum chemical cluster approach is again demonstrated to be powerful in studying the enantioselectivity of enzymatic reactions.
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Affiliation(s)
- Qinrou Li
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, P. R. China
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China.
| | - Shiqing Zhang
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China.
- National Center of Technology Innovation for Synthetic Biology, National Engineering Research Center of Industrial Enzymes and Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin 300308, P. R. China
| | - Fufeng Liu
- College of Biotechnology, Tianjin University of Science and Technology, Tianjin, 300457, P. R. China
| | - Hao Su
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China.
- National Center of Technology Innovation for Synthetic Biology, National Engineering Research Center of Industrial Enzymes and Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin 300308, P. R. China
| | - Xiang Sheng
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China.
- National Center of Technology Innovation for Synthetic Biology, National Engineering Research Center of Industrial Enzymes and Key Laboratory of Engineering Biology for Low-Carbon Manufacturing, Tianjin 300308, P. R. China
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2
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Prakinee K, Lawan N, Phintha A, Visitsatthawong S, Chitnumsub P, Jitkaroon W, Chaiyen P. On the Mechanisms of Hypohalous Acid Formation and Electrophilic Halogenation by Non-Native Halogenases. Angew Chem Int Ed Engl 2024; 63:e202403858. [PMID: 38606607 DOI: 10.1002/anie.202403858] [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: 02/24/2024] [Revised: 03/29/2024] [Accepted: 04/10/2024] [Indexed: 04/13/2024]
Abstract
Enzymatic electrophilic halogenation is a mild tool for functionalization of diverse organic compounds. Only a few groups of native halogenases are capable of catalyzing such a reaction. In this study, we used a mechanism-guided strategy to discover the electrophilic halogenation activity catalyzed by non-native halogenases. As the ability to form a hypohalous acid (HOX) is key for halogenation, flavin-dependent monooxygenases/oxidases capable of forming C4a-hydroperoxyflavin (FlC4a-OOH), such as dehalogenase, hydroxylases, luciferase and pyranose-2-oxidase (P2O), and flavin reductase capable of forming H2O2 were explored for their abilities to generate HOX in situ. Transient kinetic analyses using stopped-flow spectrophotometry/fluorometry and product analysis indicate that FlC4a-OOH in dehalogenases, selected hydroxylases and luciferases, but not in P2O can form HOX; however, the HOX generated from FlC4a-OOH cannot halogenate their substrates. Remarkably, in situ H2O2 generated by P2O can form HOI and also iodinate various compounds. Because not all enzymes capable of forming FlC4a-OOH can react with halides to form HOX, QM/MM calculations, site-directed mutagenesis and structural analysis were carried out to elucidate the mechanism underlying HOX formation and characterize the active site environment. Our findings shed light on identifying new halogenase scaffolds besides the currently known enzymes and have invoked a new mode of chemoenzymatic halogenation.
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Affiliation(s)
- Kridsadakorn Prakinee
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Narin Lawan
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Aisaraphon Phintha
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Surawit Visitsatthawong
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
| | - Penchit Chitnumsub
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, Thailand
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA) Thailand Science Park, Pathum Thani, 12120, Thailand
| | - Watcharapa Jitkaroon
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC) Wangchan Valley, Rayong, 21210, 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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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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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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5
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Pimviriyakul P, Buttranon S, Soithongcharoen S, Supawatkon C, Disayabootr K, Watthaisong P, Tinikul R, Jaruwat A, Chaiyen P, Chitnumsub P, Maenpuen S. Structure and biochemical characterization of an extradiol 3,4-dihydroxyphenylacetate 2,3-dioxygenase from Acinetobacter baumannii. Arch Biochem Biophys 2023; 747:109768. [PMID: 37769893 DOI: 10.1016/j.abb.2023.109768] [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: 08/24/2023] [Revised: 09/23/2023] [Accepted: 09/26/2023] [Indexed: 10/03/2023]
Abstract
3,4-Dihydroxyphenylacetate (DHPA) 2,3-dioxygenase (EC 1.13.11.15) from Acinetobacter baumannii (AbDHPAO) is an enzyme that catalyzes the 2,3-extradiol ring-cleavage of DHPA in the p-hydroxyphenylacetate (HPA) degradation pathway. While the biochemical reactions of various DHPAOs have been reported, only structures of DHPAO from Brevibacterium fuscum and their homologs are available. Here, we report the X-ray structure and biochemical characterization of an Fe2+-specific AbDHPAO that shares 12% sequence identity to the enzyme from B. fuscum. The 1.8 Å X-ray structure of apo-AbDHPAO was determined with four subunits per asymmetric unit, consistent with a homotetrameric structure. Interestingly, the αβ-sandwiched fold of the AbDHPAO subunit is different from the dual β-barrel-like motif of the well-characterized B. fuscum DHPAO structures; instead, it is similar to the structures of non-DHPA extradiol dioxygenases from Comamonas sp. and Sphingomonas paucimobilis. Similarly, these extradiol dioxygenases share the same chemistry owing to a conserved 2-His-1-carboxylate catalytic motif. Structure analysis and molecular docking suggested that the Fe2+ cofactor and substrate binding sites consist of the conserved residues His12, His57, and Glu238 forming a 2-His-1-carboxylate motif ligating to Fe2+ and DHPA bound with Fe2+ in an octahedral coordination. In addition to DHPA, AbDHPAO can also use other 3,4-dihydroxyphenylacetate derivatives with different aliphatic carboxylic acid substituents as substrates, albeit with low reactivity. Altogether, this report provides a better understanding of the structure and biochemical properties of AbDHPAO and its homologs, which is advancing further modification of DHPAO in future applications.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand
| | - Supacha Buttranon
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi, 20131, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Sahachat Soithongcharoen
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi, 20131, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Cheerapat Supawatkon
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi, 20131, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Kasidis Disayabootr
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi, 20131, Thailand
| | - Pratchaya Watthaisong
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Ruchanok Tinikul
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, 10400, Thailand
| | - Aritsara Jaruwat
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, 21210, Thailand
| | - Penchit Chitnumsub
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Phahonyothin road, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand.
| | - Somchart Maenpuen
- Department of Biochemistry, Faculty of Science, Burapha University, Chonburi, 20131, 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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Pimviriyakul P, Chaiyen P. Formation and stabilization of C4a-hydroperoxy-FAD by the Arg/Asn pair in HadA monooxygenase. FEBS J 2023; 290:176-195. [PMID: 35942637 DOI: 10.1111/febs.16591] [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: 06/15/2022] [Revised: 07/25/2022] [Accepted: 08/08/2022] [Indexed: 01/14/2023]
Abstract
HadA monooxygenase catalyses the detoxification of halogenated phenols and nitrophenols via dehalogenation and denitration respectively. C4a-hydroperoxy-FAD is a key reactive intermediate wherein its formation, protonation and stabilization reflect enzyme efficiency. Herein, transient kinetics, site-directed mutagenesis and pH-dependent behaviours of HadA reaction were employed to identify key features stabilizing C4a-adducts in HadA. The formation of C4a-hydroperoxy-FAD is pH independent, whereas its decay and protonation of distal oxygen are associated with pKa values of 8.5 and 8.4 respectively. These values are correlated with product formation within a pH range of 7.6-9.1, indicating the importance of adduct stabilization to enzymatic efficiency. We identified Arg101 as a key residue for reduced FAD (FADH- ) binding and C4a-hydroperoxy-FAD formation due to the loss of these abilities as well as enzyme activity in HadAR101A and HadAR101Q . Mutations of the neighbouring Asn447 do not affect the rate of C4a-hydroperoxy-FAD formation; however, they impair FADH- binding. The disruption of Arg101/Asn447 hydrogen bond networking in HadAN447A increases the pKa value of C4a-hydroperoxy-FAD decay to 9.5; however, this pKa was not altered in HadAN447D (pKa of 8.5). Thus, Arg101/Asn447 pair should provide important interactions for FADH- binding and maintain the pKa associated with H2 O2 elimination from C4a-hydroperoxy-FAD in HadA. In the presence of substrate, the formation of C4a-hydroxy-FAD at the hydroxylation step is pH insensitive, and it dehydrates to form the oxidized FAD with pKa of 7.9. This structural feature might help elucidate how the reactive intermediate was stabilized in other flavin-dependent monooxygenases.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
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8
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Comparative Genomic Analysis of Carbofuran-Degrading Sphingomonads Reveals the Carbofuran Catabolism Mechanism in
Sphingobium
sp. Strain CFD-1. Appl Environ Microbiol 2022; 88:e0102422. [PMID: 36314801 PMCID: PMC9680625 DOI: 10.1128/aem.01024-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Owing to the extensive use of carbofuran over the past 50 years, bacteria have evolved catabolic pathways to mineralize this insecticide, which plays an important role in eliminating carbofuran residue in the environment. In this study, the
cfd
gene cluster, responsible for the catabolism of carbofuran phenol, was predicted by comparing sphingomonad genomes.
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9
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Ernst S, Mährlein A, Ritzmann NH, Drees SL, Fetzner S. A comparative study of
N
‐hydroxylating flavoprotein monooxygenases reveals differences in kinetics and cofactor binding. FEBS J 2022; 289:5637-5655. [DOI: 10.1111/febs.16444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/21/2022] [Accepted: 03/18/2022] [Indexed: 12/01/2022]
Affiliation(s)
- Simon Ernst
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Almuth Mährlein
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Niklas H. Ritzmann
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Steffen L. Drees
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
| | - Susanne Fetzner
- Institute of Molecular Microbiology and Biotechnology University of Münster Germany
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10
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Mechanism-guided tunnel engineering to increase the efficiency of a flavin-dependent halogenase. Nat Catal 2022. [DOI: 10.1038/s41929-022-00800-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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11
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12
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13
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He Y, Haque MM, Stuehr DJ, Lu HP. Conformational States and Fluctuations in Endothelial Nitric Oxide Synthase under Calmodulin Regulation. Biophys J 2021; 120:5196-5206. [PMID: 34748763 DOI: 10.1016/j.bpj.2021.11.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 09/30/2021] [Accepted: 11/02/2021] [Indexed: 11/30/2022] Open
Abstract
Mechanisms that regulate nitric oxide synthase enzymes (NOS) are of interest in biology and medicine. Although NOS catalysis relies on domain motions and is activated by calmodulin (CaM) binding, the relationships are unclear. We used single-molecule fluorescence resonance energy transfer (FRET) spectroscopy to elucidate the conformational states distribution and associated conformational fluctuation dynamics of the two NOS electron transfer domains in a FRET dye-labeled endothelial NOS reductase domain (eNOSr) and to understand how CaM affects the dynamics to regulate catalysis by shaping the spatial and temporal conformational behaviors of eNOSr. In addition, we developed and applied a new imaging approach capable of recording 3D FRET efficiency vs time images to characterize the impact on dynamic conformal states of the eNOSr enzyme by the binding of CaM, which identifies clearly that CaM binding generates an extra new open state of eNOSr, resolving more detailed NOS conformational states and their fluctuation dynamics. We identified a new output state that has an extra-open FAD-FMN conformation that is only populated in the CaM-bound eNOSr. This may reveal the critical role of CaM in triggering NOS activity as it gives conformational flexibility for eNOSr to assume the electron transfer output FMN-Heme state. Our results provide a dynamic link to recently reported EM static structure analyses and demonstrate a capable approach in probing and simultaneously analyzing all of the conformational states, their fluctuations, and the fluctuation dynamics for understanding the mechanism of NOS electron transfer, involving electron transfer amongst FAD, FMN, and Heme domains, during NO synthesis.
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Affiliation(s)
- Yufan He
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - Mohammad Mahfuzul Haque
- Department of Inflammation and Immunology, Lerner Research Institute, The Cleveland Clinic, 9500 Euclid Avenue, Cleveland Clinic, Cleveland, Ohio, 44195
| | - Dennis J Stuehr
- Department of Inflammation and Immunology, Lerner Research Institute, The Cleveland Clinic, 9500 Euclid Avenue, Cleveland Clinic, Cleveland, Ohio, 44195.
| | - H Peter Lu
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403.
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14
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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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15
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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] [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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16
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Phintha A, Prakinee K, Jaruwat A, Lawan N, Visitsatthawong S, Kantiwiriyawanitch C, Songsungthong W, Trisrivirat D, Chenprakhon P, Mulholland A, van Pée KH, Chitnumsub P, Chaiyen P. Dissecting the low catalytic capability of flavin-dependent halogenases. J Biol Chem 2021; 296:100068. [PMID: 33465708 PMCID: PMC7948982 DOI: 10.1074/jbc.ra120.016004] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 12/11/2022] Open
Abstract
Although flavin-dependent halogenases (FDHs) are attractive biocatalysts, their practical applications are limited because of their low catalytic efficiency. Here, we investigated the reaction mechanisms and structures of tryptophan 6-halogenase (Thal) from Streptomyces albogriseolus using stopped-flow, rapid-quench flow, quantum/mechanics molecular mechanics calculations, crystallography, and detection of intermediate (hypohalous acid [HOX]) liberation. We found that the key flavin intermediate, C4a-hydroperoxyflavin (C4aOOH-FAD), formed by Thal and other FDHs (tryptophan 7-halogenase [PrnA] and tryptophan 5-halogenase [PyrH]), can react with I-, Br-, and Cl- but not F- to form C4a-hydroxyflavin and HOX. Our experiments revealed that I- reacts with C4aOOH-FAD the fastest with the lowest energy barrier and have shown for the first time that a significant amount of the HOX formed leaks out as free HOX. This leakage is probably a major cause of low product coupling ratios in all FDHs. Site-saturation mutagenesis of Lys79 showed that changing Lys79 to any other amino acid resulted in an inactive enzyme. However, the levels of liberated HOX of these variants are all similar, implying that Lys79 probably does not form a chloramine or bromamine intermediate as previously proposed. Computational calculations revealed that Lys79 has an abnormally lower pKa compared with other Lys residues, implying that the catalytic Lys may act as a proton donor in catalysis. Analysis of new X-ray structures of Thal also explains why premixing of FDHs with reduced flavin adenine dinucleotide generally results in abolishment of C4aOOH-FAD formation. These findings reveal the hidden factors restricting FDHs capability which should be useful for future development of FDHs applications.
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Affiliation(s)
- Aisaraphon Phintha
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Kridsadakorn Prakinee
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Aritsara Jaruwat
- Biomolecular Analysis and Application Research Team, National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand
| | - Narin Lawan
- Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Surawit Visitsatthawong
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Chadaporn Kantiwiriyawanitch
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Warangkhana Songsungthong
- Biomolecular Analysis and Application Research Team, National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand
| | - Duangthip Trisrivirat
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Pirom Chenprakhon
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom, Thailand
| | - Adrian Mulholland
- Centre for Computational Chemistry, School of Chemistry, University of Bristol, Bristol, UK
| | - Karl-Heinz van Pée
- General Biochemistry, Faculty of Chemistry and Food Chemistry, Technical University of Dresden, Dresden, Germany
| | - Penchit Chitnumsub
- Biomolecular Analysis and Application Research Team, National Center for Genetic Engineering and Biotechnology, Klong Luang, Pathumthani, Thailand.
| | - Pimchai Chaiyen
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, Thailand; School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand.
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17
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Li H, Forson B, Eckshtain-Levi M, Valentino H, Martín Del Campo JS, Tanner JJ, Sobrado P. Biochemical Characterization of the Two-Component Flavin-Dependent Monooxygenase Involved in Valanimycin Biosynthesis. Biochemistry 2020; 60:31-40. [PMID: 33350810 DOI: 10.1021/acs.biochem.0c00679] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The flavin reductase (FRED) and isobutylamine N-hydroxylase (IBAH) from Streptomyces viridifaciens constitute a two-component, flavin-dependent monooxygenase system that catalyzes the first step in valanimycin biosynthesis. FRED is an oxidoreductase that provides the reduced flavin to IBAH, which then catalyzes the hydroxylation of isobutylamine (IBA) to isobutylhydroxylamine (IBHA). In this work, we used several complementary methods to investigate FAD binding, steady-state and rapid reaction kinetics, and enzyme-enzyme interactions in the FRED:IBAH system. The affinity of FRED for FADox is higher than its affinity for FADred, consistent with its function as a flavin reductase. Conversely, IBAH binds FADred more tightly than FADox, consistent with its role as a monooxygenase. FRED exhibits a strong preference (28-fold) for NADPH over NADH as the electron source for FAD reduction. Isothermal titration calorimetry was used to study the association of FRED and IBAH. In the presence of FAD, either oxidized or reduced, FRED and IBAH associate with a dissociation constant of 7-8 μM. No interaction was observed in the absence of FAD. These results are consistent with the formation of a protein-protein complex for direct transfer of reduced flavin from the reductase to the monooxygenase in this two-component system.
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Affiliation(s)
- Hao Li
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Benedicta Forson
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Meital Eckshtain-Levi
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Hannah Valentino
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | | | - John J Tanner
- Departments of Biochemistry and Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.,Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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18
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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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19
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Abstract
Flavin-dependent enzymes catalyze a wide variety of biological reactions that are important for all types of living organisms. Knowledge gained from studying the chemistry and biological functions of flavins and flavin-dependent enzymes has continuously made significant contributions to the development of the fields of enzymology and metabolism from the 1970s until now. The enzymes have been applied in various applications such as use as biocatalysts in synthetic processes for the chemical and pharmaceutical industries or in the biodetoxification and bioremediation of toxic or unwanted compounds, and as biosensors or biodetection tools for quantifying various agents of interest. Many flavin-dependent enzymes are also prime targets for drug development. Based on their reaction mechanisms, they can be classified into five categories: oxidase, dehydrogenase, monooxygenase, reductase, and redox neutral flavin-dependent enzymes. In this chapter, the general properties of flavin-dependent enzymes and the nature of their chemical reactions are discussed, along with their practical applications.
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20
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Abstract
Bacterial luciferase is a flavin-dependent monooxygenase which is remarkable for its distinctive feature in transforming chemical energy to photons of visible light. The bacterial luciferase catalyzes bioluminescent reaction using reduced flavin mononucleotide, long-chain aldehyde and oxygen to yield oxidized flavin, corresponding acid, water and light at λmax around 490nm. The enzyme comprises of two non-identical α and β subunits, where α subunit is a catalytic center and β subunit is crucially required for maintaining catalytic function of the α subunit. The crystal structure with FMN bound and mutagenesis studies have assigned a number of amino acid residues that are important in coordinating critical reactions and stabilizing intermediates to attain optimum reaction efficiency. The enzyme achieves monooxygenation by generating C4a-hydroperoxyflavin intermediate that later changes its protonation status to become C4a-peroxyflavin, which is necessary for the nucleophilic attacking with aldehyde substrate. The decomposing of C4a-peroxyhemiacetal produces excited C4a-hydroxyflavin and acid product. The chemical basis regrading bioluminophore generation in Lux reaction remains an inconclusive issue. However, current data can, at least, demonstrate the involvement of electron transfer to create radical molecules which is the key step in this mechanism. Lux is a self-sufficient bioluminescent system in which all substrates can be recycled and produced by a group of enzymes from the lux operon. This makes Lux distinctively advantageous over other luciferases for reporter enzyme application. The progression of understanding of Lux catalysis is beneficial to improve light emitting efficiency in order to expand the robustness of Lux application.
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21
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Pitsawong W, Chenprakhon P, Dhammaraj T, Medhanavyn D, Sucharitakul J, Tongsook C, van Berkel WJH, Chaiyen P, Miller AF. Tuning of p Ka values activates substrates in flavin-dependent aromatic hydroxylases. J Biol Chem 2020; 295:3965-3981. [PMID: 32014994 DOI: 10.1074/jbc.ra119.011884] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 01/29/2020] [Indexed: 12/31/2022] Open
Abstract
Hydroxylation of substituted phenols by flavin-dependent monooxygenases is the first step of their biotransformation in various microorganisms. The reaction is thought to proceed via electrophilic aromatic substitution, catalyzed by enzymatic deprotonation of substrate, in single-component hydroxylases that use flavin as a cofactor (group A). However, two-component hydroxylases (group D), which use reduced flavin as a co-substrate, are less amenable to spectroscopic investigation. Herein, we employed 19F NMR in conjunction with fluorinated substrate analogs to directly measure pKa values and to monitor protein events in hydroxylase active sites. We found that the single-component monooxygenase 3-hydroxybenzoate 6-hydroxylase (3HB6H) depresses the pKa of the bound substrate analog 4-fluoro-3-hydroxybenzoate (4F3HB) by 1.6 pH units, consistent with previously proposed mechanisms. 19F NMR was applied anaerobically to the two-component monooxygenase 4-hydroxyphenylacetate 3-hydroxylase (HPAH), revealing depression of the pKa of 3-fluoro-4-hydroxyphenylacetate by 2.5 pH units upon binding to the C2 component of HPAH. 19F NMR also revealed a pKa of 8.7 ± 0.05 that we attributed to an active-site residue involved in deprotonating bound substrate, and assigned to His-120 based on studies of protein variants. Thus, in both types of hydroxylases, we confirmed that binding favors the phenolate form of substrate. The 9 and 14 kJ/mol magnitudes of the effects for 3HB6H and HPAH-C2, respectively, are consistent with pKa tuning by one or more H-bonding interactions. Our implementation of 19F NMR in anaerobic samples is applicable to other two-component flavin-dependent hydroxylases and promises to expand our understanding of their catalytic mechanisms.
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Affiliation(s)
- Warintra Pitsawong
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055
| | - Pirom Chenprakhon
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Taweesak Dhammaraj
- Faculty of Pharmacy, Mahasarakham University, Maha Sarakham 44150, Thailand
| | - Dheeradhach Medhanavyn
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Jeerus Sucharitakul
- Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Bangkok 10300, Thailand
| | - Chanakan Tongsook
- Department of Chemistry, Faculty of Science, Silpakorn University, Nakhon Pathom 73000, Thailand
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University and Research, Bornse Weilanden 9, 6708 WG, Wageningen, The Netherlands
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology, Wangchan Valley, 555 Moo 1 Payupnai, Wangchan, Rayong 21210, Thailand
| | - Anne-Frances Miller
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055
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22
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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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23
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Catalytic mechanism for the conversion of salicylate into catechol by the flavin-dependent monooxygenase salicylate hydroxylase. Int J Biol Macromol 2019; 129:588-600. [DOI: 10.1016/j.ijbiomac.2019.01.135] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 11/17/2022]
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24
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Pimviriyakul P, Chaiyen P. A complete bioconversion cascade for dehalogenation and denitration by bacterial flavin-dependent enzymes. J Biol Chem 2018; 293:18525-18539. [PMID: 30282807 DOI: 10.1074/jbc.ra118.005538] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 09/29/2018] [Indexed: 12/17/2022] Open
Abstract
Halogenated phenol and nitrophenols are toxic compounds that are widely accumulated in the environment. Enzymes in the had operon from the bacterium Ralstonia pickettii DTP0602 have the potential for application as biocatalysts in the degradation of many of these toxic chemicals. HadA monooxygenase previously was identified as a two-component reduced FAD (FADH-)-utilizing monooxygenase with dual activities of dehalogenation and denitration. However, the partner enzymes of HadA, that is, the flavin reductase and quinone reductase that provide the FADH- for HadA and reduce quinone to hydroquinone, remain to be identified. In this report, we overexpressed and purified the flavin reductases, HadB and HadX, to investigate their functional and catalytic properties. Our results indicated that HadB is an FMN-dependent quinone reductase that converts the quinone products from HadA to hydroquinone compounds that are more stable and can be assimilated by downstream enzymes in the pathway. Transient kinetics indicated that HadB prefers NADH and menadione as the electron donor and acceptor, respectively. We found that HadX is an FAD-bound flavin reductase, which can generate FADH- for HadA to catalyze dehalogenation or denitration reactions. Thermodynamic and transient kinetic experiments revealed that HadX prefers to bind FAD over FADH- and that HadX can transfer FADH- from HadX to HadA via free diffusion. Moreover, HadX rapidly catalyzed NADH-mediated reduction of flavin and provided the FADH- for a monooxygenase of a different system. Combination of all three flavin-dependent enzymes, i.e. HadA/HadB/HadX, reconstituted an effective dehalogenation and denitration cascade, which may be useful for future bioremediation applications.
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Affiliation(s)
- Panu Pimviriyakul
- From the School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong 21210 and.,the Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 14000, Thailand
| | - Pimchai Chaiyen
- From the School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Wangchan Valley, Rayong 21210 and
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25
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Hydrolase CehA and Monooxygenase CfdC Are Responsible for Carbofuran Degradation in Sphingomonas sp. Strain CDS-1. Appl Environ Microbiol 2018; 84:AEM.00805-18. [PMID: 29884759 DOI: 10.1128/aem.00805-18] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 05/31/2018] [Indexed: 01/29/2023] Open
Abstract
Carbofuran, a broad-spectrum systemic insecticide, has been extensively used for approximately 50 years. Diverse carbofuran-degrading bacteria have been described, among which sphingomonads have exhibited an extraordinary ability to catabolize carbofuran; other bacteria can only convert carbofuran to carbofuran phenol, while all carbofuran-degrading sphingomonads can degrade both carbofuran and carbofuran phenol. However, the genetic basis of carbofuran catabolism in sphingomonads has not been well elucidated. In this work, we sequenced the draft genome of Sphingomonas sp. strain CDS-1 that can transform both carbofuran and carbofuran phenol but fails to grow on them. On the basis of the hypothesis that the genes involved in carbofuran catabolism are highly conserved among carbofuran-degrading sphingomonads, two such genes, cehACDS-1 and cfdCCDS-1, were predicted from the 84 open reading frames (ORFs) that share ≥95% nucleic acid similarities between strain CDS-1 and another sphingomonad Novosphingobium sp. strain KN65.2 that is able to mineralize the benzene ring of carbofuran. The results of the gene knockout, genetic complementation, heterologous expression, and enzymatic experiments reveal that cehACDS-1 and cfdCCDS-1 are responsible for the conversion of carbofuran and carbofuran phenol, respectively, in strain CDS-1. CehACDS-1 hydrolyzes carbofuran to carbofuran phenol. CfdCCDS-1, a reduced flavin mononucleotide (FMNH2)- or reduced flavin adenine dinucleotide (FADH2)-dependent monooxygenase, hydroxylates carbofuran phenol at the benzene ring in the presence of NADH, FMN/FAD, and the reductase CfdX. It is worth noting that we found that carbaryl hydrolase CehAAC100, which was previously demonstrated to have no activity toward carbofuran, can actually convert carbofuran to carbofuran phenol, albeit with very low activity.IMPORTANCE Due to the extensive use of carbofuran over the past 50 years, bacteria have evolved catabolic pathways to mineralize this insecticide, which plays an important role in eliminating carbofuran residue in the environment. This study revealed the genetic determinants of carbofuran degradation in Sphingomonas sp. strain CDS-1. We speculate that the close homologues cehA and cfdC are highly conserved among other carbofuran-degrading sphingomonads and play the same roles as those described here. These findings deepen our understanding of the microbial degradation mechanism of carbofuran and lay a foundation for the better use of microbes to remediate carbofuran contamination.
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26
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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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27
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Hazra AB, Ballou DP, Taga ME. Unique Biochemical and Sequence Features Enable BluB To Destroy Flavin and Distinguish BluB from the Flavin Monooxygenase Superfamily. Biochemistry 2018; 57:1748-1757. [PMID: 29457884 DOI: 10.1021/acs.biochem.7b01193] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Vitamin B12 (cobalamin) is an essential micronutrient for humans that is synthesized by only a subset of bacteria and archaea. The aerobic biosynthesis of 5,6-dimethylbenzimidazole, the lower axial ligand of cobalamin, is catalyzed by the "flavin destructase" enzyme BluB, which fragments reduced flavin mononucleotide following its reaction with oxygen to yield this ligand. BluB is similar in sequence and structure to members of the flavin oxidoreductase superfamily, yet the flavin destruction process has remained elusive. Using stopped-flow spectrophotometry, we find that the flavin destructase reaction of BluB from Sinorhizobium meliloti is initiated with canonical flavin-O2 chemistry. A C4a-peroxyflavin intermediate is rapidly formed in BluB upon reaction with O2, and has properties similar to those of flavin-dependent hydroxylases. Analysis of reaction mixtures containing flavin analogues indicates that both formation of the C4a-peroxyflavin and the subsequent destruction of the flavin to form 5,6-dimethylbenzimidazole are influenced by the electronic properties of the flavin isoalloxazine ring. The flavin destruction phase of the reaction, which results from the decay of the C4a-peroxyflavin intermediate, occurs more efficiently at pH >7.5. Furthermore, the BluB mutants D32N and S167G are specifically impaired in the flavin destruction phase of the reaction; nevertheless, both form the C4a-peroxyflavin nearly quantitatively. Coupled with a phylogenetic analysis of BluB and related flavin-dependent enzymes, these results demonstrate that the BluB flavin destructase family can be identified by the presence of active site residues D32 and S167.
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Affiliation(s)
- Amrita B Hazra
- Department of Plant & Microbial Biology , University of California, Berkeley , Berkeley , California 94720 , United States.,Department of Chemistry , Indian Institute of Science Education and Research Pune , Pune - 411008 , India
| | - David P Ballou
- Department of Biological Chemistry , University of Michigan , Ann Arbor , Michigan 48109 , United States
| | - Michiko E Taga
- Department of Plant & Microbial Biology , University of California, Berkeley , Berkeley , California 94720 , United States
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Tinikul R, Chenprakhon P, Maenpuen S, Chaiyen P. Biotransformation of Plant-Derived Phenolic Acids. Biotechnol J 2018; 13:e1700632. [DOI: 10.1002/biot.201700632] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/10/2017] [Indexed: 01/18/2023]
Affiliation(s)
- Ruchanok Tinikul
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology; Faculty of Science; Mahidol University; Bangkok 10400 Thailand
| | - Pirom Chenprakhon
- Institute for Innovative Learning; Mahidol University; Nakhon Pathom 73170 Thailand
| | - Somchart Maenpuen
- Department of Biochemistry; Faculty of Science; Burapha University; Chonburi 20131 Thailand
| | - Pimchai Chaiyen
- Department of Biomolecular Science and Engineering; School of Biomolecular Science & Engineering; Vidyasirimedhi Institute of Science and Technology (VISTEC); Wangchan Valley Rayong 21210 Thailand
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29
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Romero E, Gómez Castellanos JR, Gadda G, Fraaije MW, Mattevi A. Same Substrate, Many Reactions: Oxygen Activation in Flavoenzymes. Chem Rev 2018; 118:1742-1769. [DOI: 10.1021/acs.chemrev.7b00650] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Elvira Romero
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - J. Rubén Gómez Castellanos
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
| | - Giovanni Gadda
- Departments of Chemistry and Biology, Center for Diagnostics and Therapeutics, and Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia 30302-3965, United States
| | - Marco W. Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Via Ferrata 9, 27100 Pavia, Italy
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30
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Webb BA, Compton KK, Del Campo JSM, Taylor D, Sobrado P, Scharf BE. Sinorhizobium meliloti Chemotaxis to Multiple Amino Acids Is Mediated by the Chemoreceptor McpU. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:770-777. [PMID: 28745538 DOI: 10.1094/mpmi-04-17-0096-r] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The legume symbiont Sinorhizobium meliloti is chemoattracted to compounds exuded by germinating seeds of its host alfalfa. This response is mainly mediated by the S. meliloti chemoreceptor McpU. McpU also has a prominent contribution in sensing a synthetic amino acid (aa) mixture mimicking the amounts and composition observed in seed exudate. Here, we used the hydrogel capillary assay to quantify chemotactic responses of S. meliloti to individual aa exuded by germinating alfalfa seeds and to define the role of McpU in this behavior. S. meliloti exhibited positive chemotaxis responses to all proteinogenic aa, except for aspartate, and to citrulline, cystine, gamma-aminobutyric acid, and ornithine. Wild-type responses were diverse in intensity, while a strain lacking mcpU displayed strongly diminished responses. Differential scanning fluorimetry demonstrated interaction of the purified periplasmic region of McpU (McpU-PR) with the aa, except glutamate and aspartate. We additionally tested organic acids and sugars, but there were no significant interactions with the McpU ligand-binding domain, except for citrate. Using ligand displacement, we confirmed the interaction of McpU-PR with aa representing strong and weak attractants. Our results show that S. meliloti McpU is a broad-range aa receptor mediating differential responses to individual attractants, which does not bind negatively charged aa.
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Affiliation(s)
- Benjamin A Webb
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
| | - K Karl Compton
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
| | | | - Doris Taylor
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
| | - Pablo Sobrado
- 2 Virginia Tech, Department of Biochemistry, Fralin Life Science Institute
| | - Birgit E Scharf
- 1 Virginia Tech, Department of Biological Sciences, Life Sciences I, Blacksburg, VA 24061, U.S.A.; and
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31
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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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The Two-Component Monooxygenase MeaXY Initiates the Downstream Pathway of Chloroacetanilide Herbicide Catabolism in Sphingomonads. Appl Environ Microbiol 2017; 83:AEM.03241-16. [PMID: 28115384 DOI: 10.1128/aem.03241-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/18/2017] [Indexed: 11/20/2022] Open
Abstract
Due to the extensive use of chloroacetanilide herbicides over the past 60 years, bacteria have evolved catabolic pathways to mineralize these compounds. In the upstream catabolic pathway, chloroacetanilide herbicides are transformed into the two common metabolites 2-methyl-6-ethylaniline (MEA) and 2,6-diethylaniline (DEA) through N-dealkylation and amide hydrolysis. The pathway downstream of MEA is initiated by the hydroxylation of aromatic rings, followed by its conversion to a substrate for ring cleavage after several steps. Most of the key genes in the pathway have been identified. However, the genes involved in the initial hydroxylation step of MEA are still unknown. As a special aniline derivative, MEA cannot be transformed by the aniline dioxygenases that have been characterized. Sphingobium baderi DE-13 can completely degrade MEA and use it as a sole carbon source for growth. In this work, an MEA degradation-deficient mutant of S. baderi DE-13 was isolated. MEA catabolism genes were predicted through comparative genomic analysis. The results of genetic complementation and heterologous expression demonstrated that the products of meaX and meaY are responsible for the initial step of MEA degradation in S. baderi DE-13. MeaXY is a two-component flavoprotein monooxygenase system that catalyzes the hydroxylation of MEA and DEA using NADH and flavin mononucleotide (FMN) as cofactors. Nuclear magnetic resonance (NMR) analysis confirmed that MeaXY hydroxylates MEA and DEA at the para-position. Transcription of meaX was enhanced remarkably upon induction of MEA or DEA in S. baderi DE-13. Additionally, meaX and meaY were highly conserved among other MEA-degrading sphingomonads. This study fills a gap in our knowledge of the biochemical pathway that carries out mineralization of chloroacetanilide herbicides in sphingomonads.IMPORTANCE Much attention has been paid to the environmental fate of chloroacetanilide herbicides used for the past 60 years. Microbial degradation is considered an important mechanism in the degradation of these compounds. Bacterial degradation of chloroacetanilide herbicides has been investigated in many recent studies. Pure cultures or consortia able to mineralize these herbicides have been obtained. The catabolic pathway has been proposed, and most key genes involved have been identified. However, the genes responsible for the initiation step (from MEA to hydroxylated MEA or from DEA to hydroxylated DEA) of the downstream pathway have not been reported. The present study demonstrates that a two-component flavin-dependent monooxygenase system, MeaXY, catalyzes the para-hydroxylation of MEA or DEA in sphingomonads. Therefore, this work finds a missing link in the biochemical pathway that carries out the mineralization of chloroacetanilide herbicides in sphingomonads. Additionally, the results expand our understanding of the degradation of a special kind of aniline derivative.
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Pimviriyakul P, Thotsaporn K, Sucharitakul J, Chaiyen P. Kinetic Mechanism of the Dechlorinating Flavin-dependent Monooxygenase HadA. J Biol Chem 2017; 292:4818-4832. [PMID: 28159841 DOI: 10.1074/jbc.m116.774448] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 01/30/2017] [Indexed: 01/26/2023] Open
Abstract
The accumulation of chlorophenols (CPs) in the environment, due to their wide use as agrochemicals, has become a serious environmental problem. These organic halides can be degraded by aerobic microorganisms, where the initial steps of various biodegradation pathways include an oxidative dechlorinating process in which chloride is replaced by a hydroxyl substituent. Harnessing these dechlorinating processes could provide an opportunity for environmental remediation, but detailed catalytic mechanisms for these enzymes are not yet known. To close this gap, we now report transient kinetics and product analysis of the dechlorinating flavin-dependent monooxygenase, HadA, from the aerobic organism Ralstonia pickettii DTP0602, identifying several mechanistic properties that differ from other enzymes in the same class. We first overexpressed and purified HadA to homogeneity. Analyses of the products from single and multiple turnover reactions demonstrated that HadA prefers 4-CP and 2-CP over CPs with multiple substituents. Stopped-flow and rapid-quench flow experiments of HadA with 4-CP show the involvement of specific intermediates (C4a-hydroperoxy-FAD and C4a-hydroxy-FAD) in the reaction, define rate constants and the order of substrate binding, and demonstrate that the hydroxylation step occurs prior to chloride elimination. The data also identify the non-productive and productive paths of the HadA reactions and demonstrate that product formation is the rate-limiting step. This is the first elucidation of the kinetic mechanism of a two-component flavin-dependent monooxygenase that can catalyze oxidative dechlorination of various CPs, and as such it will serve as the basis for future investigation of enzyme variants that will be useful for applications in detoxifying chemicals hazardous to human health.
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Affiliation(s)
- Panu Pimviriyakul
- From the Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400 and
| | - Kittisak Thotsaporn
- the Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Bangkok 10300, Thailand
| | - Jeerus Sucharitakul
- the Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Bangkok 10300, Thailand
| | - Pimchai Chaiyen
- From the Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok 10400 and
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34
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Thotsaporn K, Tinikul R, Maenpuen S, Phonbuppha J, Watthaisong P, Chenprakhon P, Chaiyen P. Enzymes in the p-hydroxyphenylacetate degradation pathway of Acinetobacter baumannii. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.09.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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35
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Gonzalez-Osorio L, Luong K, Jirde S, Palfey BA, Vey JL. Initial investigations of C4a-(hydro)peroxyflavin intermediate formation by dibenzothiophene monooxygenase. Biochem Biophys Res Commun 2016; 481:189-194. [PMID: 27815073 DOI: 10.1016/j.bbrc.2016.10.145] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 10/29/2016] [Indexed: 11/17/2022]
Abstract
Dibenzothiophene monooxygenase is the initiating enzyme in the Rhodococcus 4S biodesulfurization pathway. A member of the Class D flavin monooxygenases, it uses FMN to activate molecular oxygen for oxygenation of the substrate, dibenzothiophene. Here, we have used stopped-flow spectrophotometry to show that DszC forms a peroxyflavin intermediate in the absence of substrate. Mutagenesis of Ser163 and His391 to Ala appears to decrease the binding affinity for reduced FMN and eliminates the enzyme's ability to stabilize the peroxyflavin intermediate.
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Affiliation(s)
- Liliana Gonzalez-Osorio
- Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, CA 91330-8262, United States
| | - Kelvin Luong
- Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, CA 91330-8262, United States
| | - Samatar Jirde
- Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, CA 91330-8262, United States
| | - Bruce A Palfey
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109, United States; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI 48109, United States
| | - Jessica L Vey
- Department of Chemistry and Biochemistry, California State University, Northridge, Northridge, CA 91330-8262, United States.
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36
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Dhammaraj T, Pinthong C, Visitsatthawong S, Tongsook C, Surawatanawong P, Chaiyen P. A Single-Site Mutation at Ser146 Expands the Reactivity of the Oxygenase Component of p-Hydroxyphenylacetate 3-Hydroxylase. ACS Chem Biol 2016; 11:2889-2896. [PMID: 27541707 DOI: 10.1021/acschembio.6b00402] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The oxygenase component (C2) of p-hydroxyphenylacetate (4-HPA) 3-hydroxylase (HPAH) from Acinetobacter baumannii catalyzes the hydroxylation of various phenolic acids. In this report, we found that substitution of a residue close to the phenolic group binding site to yield the S146A variant resulted in an enzyme that is more effective than the wild-type in catalyzing the hydroxylation of 4-aminophenylacetate (4-APA). Product yields for both wild-type and S146A enzymes are better at lower pH values. Multiple turnover reactions of the wild-type and S146A enzymes indicate that both enzymes first hydroxylate 3-APA to give 3-hydroxy-4-aminophenylacetate (3-OH-4-APA), which is further hydroxylated to give 3,5-dihydroxy-4-aminophenylacetate, similar to the reaction of C2 with 4-HPA. Stopped-flow experiments showed that 4-APA can only bind to the wild-type enzyme at pH 6.0 and not at pH 9.0, while it can bind to S146A under both pH conditions. Rapid-quench flow results indicate that the wild-type enzyme has low reactivity toward 4-APA hydroxylation, with a hydroxylation rate constant (kOH) for 4-APA of 0.028 s-1 compared to 17 s-1 for 4-HPA, the native substrate. In contrast, for S146A, the hydroxylation rate constants for both substrates are very similar (2.6 s-1 for 4-HPA versus 2.5 s-1 for 4-APA). These data indicate that Ser146 is a key catalytic residue involved in optimizing C2 reactivity toward a phenolic compound. Removing this hydroxyl group expands C2 activity toward a non-natural aniline substrate. This understanding should be helpful for future rational engineering of other two-component flavin-dependent monooxygenases that have this conserved Ser residue.
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Affiliation(s)
- Taweesak Dhammaraj
- Department
of Biochemistry and Center for Excellence in Protein and Enzyme Technology,
Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Chatchadaporn Pinthong
- Department
of Biochemistry and Center for Excellence in Protein and Enzyme Technology,
Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
- Institute
for Innovative Learning, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Surawit Visitsatthawong
- Department
of Chemistry and Center of Excellence for Innovation in Chemistry,
Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Chanakan Tongsook
- Department
of Biochemistry and Center for Excellence in Protein and Enzyme Technology,
Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Panida Surawatanawong
- Department
of Chemistry and Center of Excellence for Innovation in Chemistry,
Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Pimchai Chaiyen
- Department
of Biochemistry and Center for Excellence in Protein and Enzyme Technology,
Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
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37
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Isupov MN, Schröder E, Gibson RP, Beecher J, Donadio G, Saneei V, Dcunha SA, McGhie EJ, Sayer C, Davenport CF, Lau PC, Hasegawa Y, Iwaki H, Kadow M, Balke K, Bornscheuer UT, Bourenkov G, Littlechild JA. The oxygenating constituent of 3,6-diketocamphane monooxygenase from the CAM plasmid of Pseudomonas putida: the first crystal structure of a type II Baeyer-Villiger monooxygenase. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2015; 71:2344-53. [PMID: 26527149 PMCID: PMC4631483 DOI: 10.1107/s1399004715017939] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 09/24/2015] [Indexed: 12/31/2022]
Abstract
The three-dimensional structures of the native enzyme and the FMN complex of the overexpressed form of the oxygenating component of the type II Baeyer-Villiger 3,6-diketocamphane monooxygenase have been determined to 1.9 Å resolution. The structure of this dimeric FMN-dependent enzyme, which is encoded on the large CAM plasmid of Pseudomonas putida, has been solved by a combination of multiple anomalous dispersion from a bromine crystal soak and molecular replacement using a bacterial luciferase model. The orientation of the isoalloxazine ring of the FMN cofactor in the active site of this TIM-barrel fold enzyme differs significantly from that previously observed in enzymes of the bacterial luciferase-like superfamily. The Ala77 residue is in a cis conformation and forms a β-bulge at the C-terminus of β-strand 3, which is a feature observed in many proteins of this superfamily.
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Affiliation(s)
- Michail N. Isupov
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Ewald Schröder
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Robert P. Gibson
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Jean Beecher
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Giuliana Donadio
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Vahid Saneei
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Stephlina A. Dcunha
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Emma J. McGhie
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Christopher Sayer
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Colin F. Davenport
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
| | - Peter C. Lau
- Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montreal, QC H4P 2R2, Canada
| | - Yoshie Hasegawa
- Department of Biotechnology, Faculty of Engineering, Kansai University, Japan
| | - Hiroaki Iwaki
- Department of Biotechnology, Faculty of Engineering, Kansai University, Japan
| | - Maria Kadow
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix-Hausdorff-Strasse 4, 17487 Greifswald, Germany
| | - Kathleen Balke
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix-Hausdorff-Strasse 4, 17487 Greifswald, Germany
| | - Uwe T. Bornscheuer
- Department of Biotechnology and Enzyme Catalysis, Institute of Biochemistry, Greifswald University, Felix-Hausdorff-Strasse 4, 17487 Greifswald, Germany
| | - Gleb Bourenkov
- European Molecular Biology Laboratory (EMBL), Hamburg Outstation, Notkestrasse 85, 22607 Hamburg, Germany
| | - Jennifer A. Littlechild
- The Henry Wellcome Building for Biocatalysis, Biosciences, College of Life and Environmental Sciences, University of Exeter, Stocker Road, Exeter EX4 4QD, England
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38
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He Y, Haque MM, Stuehr DJ, Lu HP. Single-molecule spectroscopy reveals how calmodulin activates NO synthase by controlling its conformational fluctuation dynamics. Proc Natl Acad Sci U S A 2015; 112:11835-40. [PMID: 26311846 PMCID: PMC4586839 DOI: 10.1073/pnas.1508829112] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mechanisms that regulate the nitric oxide synthase enzymes (NOS) are of interest in biology and medicine. Although NOS catalysis relies on domain motions, and is activated by calmodulin binding, the relationships are unclear. We used single-molecule fluorescence resonance energy transfer (FRET) spectroscopy to elucidate the conformational states distribution and associated conformational fluctuation dynamics of the two electron transfer domains in a FRET dye-labeled neuronal NOS reductase domain, and to understand how calmodulin affects the dynamics to regulate catalysis. We found that calmodulin alters NOS conformational behaviors in several ways: It changes the distance distribution between the NOS domains, shortens the lifetimes of the individual conformational states, and instills conformational discipline by greatly narrowing the distributions of the conformational states and fluctuation rates. This information was specifically obtainable only by single-molecule spectroscopic measurements, and reveals how calmodulin promotes catalysis by shaping the physical and temporal conformational behaviors of NOS.
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Affiliation(s)
- Yufan He
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403
| | - Mohammad Mahfuzul Haque
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - Dennis J Stuehr
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195
| | - H Peter Lu
- Center for Photochemical Sciences, Department of Chemistry, Bowling Green State University, Bowling Green, OH 43403;
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39
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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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40
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Dhammaraj T, Phintha A, Pinthong C, Medhanavyn D, Tinikul R, Chenprakhon P, Sucharitakul J, Vardhanabhuti N, Jiarpinitnun C, Chaiyen P. p-Hydroxyphenylacetate 3-Hydroxylase as a Biocatalyst for the Synthesis of Trihydroxyphenolic Acids. ACS Catal 2015. [DOI: 10.1021/acscatal.5b00439] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Taweesak Dhammaraj
- Department of Biochemistry and Center of
Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Aisaraphon Phintha
- Department of Biochemistry and Center of
Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Chatchadaporn Pinthong
- Department of Biochemistry and Center of
Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Dheeradhach Medhanavyn
- Department of Biochemistry and Center of
Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand
| | - Ruchanok Tinikul
- Mahidol University, Nakhonsawan Campus, Nakhonsawan 60130, Thailand
| | - Pirom Chenprakhon
- Institute for Innovative Learning, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Jeerus Sucharitakul
- Department
of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant
Road, Patumwan, Bangkok 10300, Thailand
| | - Nontima Vardhanabhuti
- Department of Pharmacy,
Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok 10300, Thailand
| | - Chutima Jiarpinitnun
- Department of Chemistry
and Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand
| | - Pimchai Chaiyen
- 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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41
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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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42
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Chenprakhon P, Trisrivirat D, Thotsaporn K, Sucharitakul J, Chaiyen P. Control of C4a-Hydroperoxyflavin Protonation in the Oxygenase Component of p-Hydroxyphenylacetate-3-hydroxylase. Biochemistry 2014; 53:4084-6. [DOI: 10.1021/bi500480n] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
| | | | - Kittisak Thotsaporn
- Department
of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant, Patumwan, Bangkok 10300, Thailand
| | - Jeerus Sucharitakul
- Department
of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant, Patumwan, Bangkok 10300, Thailand
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43
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Willetts A, Kelly DR. Multiple native flavin reductases in camphor-metabolizing Pseudomonas putida NCIMB 10007: functional interaction with two-component diketocamphane monooxygenase isoenzymes. MICROBIOLOGY-SGM 2014; 160:1783-1794. [PMID: 24836624 DOI: 10.1099/mic.0.079913-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Although they have been studied for nearly 50 years, the source of the FMNH2 needed for effective biooxidation by the 2,5- and 3,6-diketocamphane monooxygenase (DKCMO) isoenzymes induced by the growth of Pseudomonas putida NCIMB 10007 (ATCC 17453) on camphor remains incompletely characterized. Prior studies have focussed exclusively on enzymes present in cells harvested during late-exponential-phase growth despite considerable circumstantial evidence that the flavin reductase (FR) component of these multicomponent monooxygenases is subject to growth-phase-dependent variation. In this study, a number of alternative FMNH2-generating activities, including both conventional FRs and enzymes also able to serve as ferric reductases, were isolated from camphor-grown cells, and the relative level, and hence potential contribution, of these various proteins shown to vary considerably depending on the point of harvest of NCIMB 10007 within exponential-phase growth. While two constitutive monomeric ferric reductases (molecular masses 27.0 and 28.5 kDa) were found to be the major relevant sources of FMNH2 during the initial stages of growth on camphor-based media, a significant subsequent contribution throughout the mid- to late-exponential phases of growth was also made by the camphor-induced homodimeric 37.0 kDa FR Fred, recently reported to serve such a role exclusively. The possible involvement of camphor-induced putidaredoxin reductase (51.0 kDa) as a contributory activity was also investigated and considered. Studies with highly purified preparations of the isofunctional DKCMOs confirmed the potential of the various reductases to function effectively as sources of the requisite FMNH2 to both monooxygenases at different times throughout growth on camphor.
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Affiliation(s)
- Andrew Willetts
- Department of Biological Sciences, University of Exeter, Exeter EX4 4QG, UK
| | - David R Kelly
- Department of Chemistry, University of Wales College of Cardiff, Cardiff CF1 3TB, UK
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44
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Huijbers MME, Montersino S, Westphal AH, Tischler D, van Berkel WJH. Flavin dependent monooxygenases. Arch Biochem Biophys 2013; 544:2-17. [PMID: 24361254 DOI: 10.1016/j.abb.2013.12.005] [Citation(s) in RCA: 359] [Impact Index Per Article: 32.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 11/29/2022]
Abstract
Flavin-dependent monooxygenases catalyze a wide variety of chemo-, regio- and enantioselective oxygenation reactions. As such, they are involved in key biological processes ranging from catabolism, detoxification and biosynthesis, to light emission and axon guidance. Based on fold and function, flavin-dependent monooxygenases can be distributed into eight groups. Groups A and B comprise enzymes that rely on NAD(P)H as external electron donor. Groups C-F are two-protein systems, composed of a monooxygenase and a flavin reductase. Groups G and H comprise internal monooxygenases that reduce the flavin cofactor through substrate oxidation. Recently, many new flavin-dependent monooxygenases have been discovered. In addition to posing basic enzymological questions, these proteins attract attention of pharmaceutical and fine-chemical industries, given their importance as regio- and enantioselective biocatalysts. In this review we present an update of the classification of flavin-dependent monooxygenases and summarize the latest advances in our understanding of their catalytic and structural properties.
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Affiliation(s)
- Mieke M E Huijbers
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
| | - Stefania Montersino
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
| | - Adrie H Westphal
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
| | - Dirk Tischler
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands; Interdisciplinary Ecological Center, TU Bergakademie Freiberg, Leipziger Str. 29, 09599 Freiberg, Germany
| | - Willem J H van Berkel
- Laboratory of Biochemistry, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
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45
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Sucharitakul J, Tongsook C, Pakotiprapha D, van Berkel WJH, Chaiyen P. The reaction kinetics of 3-hydroxybenzoate 6-hydroxylase from Rhodococcus jostii RHA1 provide an understanding of the para-hydroxylation enzyme catalytic cycle. J Biol Chem 2013; 288:35210-21. [PMID: 24129570 DOI: 10.1074/jbc.m113.515205] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
3-Hydroxybenzoate 6-hydroxylase (3HB6H) from Rhodococcus jostii RHA1 is an NADH-specific flavoprotein monooxygenase that catalyzes the para-hydroxylation of 3-hydroxybenzoate (3HB) to form 2,5-dihydroxybenzoate (2,5-DHB). Based on results from stopped-flow spectrophotometry, the reduced enzyme-3HB complex reacts with oxygen to form a C4a-peroxy flavin with a rate constant of 1.13 ± 0.01 × 10(6) m(-1) s(-1) (pH 8.0, 4 °C). This intermediate is subsequently protonated to form a C4a-hydroperoxyflavin with a rate constant of 96 ± 3 s(-1). This step shows a solvent kinetic isotope effect of 1.7. Based on rapid-quench measurements, the hydroxylation occurs with a rate constant of 36 ± 2 s(-1). 3HB6H does not exhibit substrate inhibition on the flavin oxidation step, a common characteristic found in most ortho-hydroxylation enzymes. The apparent kcat at saturating concentrations of 3HB, NADH, and oxygen is 6.49 ± 0.02 s(-1). Pre-steady state and steady-state kinetic data were used to construct the catalytic cycle of the reaction. The data indicate that the steps of product release (11.7 s(-1)) and hydroxylation (36 ± 2 s(-1)) partially control the overall turnover.
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Affiliation(s)
- Jeerus Sucharitakul
- From the Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri Dunant Road, Patumwan, Bangkok 10330, Thailand
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46
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Tinikul R, Pitsawong W, Sucharitakul J, Nijvipakul S, Ballou DP, Chaiyen P. The transfer of reduced flavin mononucleotide from LuxG oxidoreductase to luciferase occurs via free diffusion. Biochemistry 2013; 52:6834-43. [PMID: 24004065 DOI: 10.1021/bi4006545] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Bacterial luciferase (LuxAB) is a two-component flavin mononucleotide (FMN)-dependent monooxygenase that catalyzes the oxidation of reduced FMN (FMNH(-)) and a long-chain aliphatic aldehyde by molecular oxygen to generate oxidized FMN, the corresponding aliphatic carboxylic acid, and concomitant emission of light. The LuxAB reaction requires a flavin reductase to generate FMNH(-) to serve as a luciferin in its reaction. However, FMNH(-) is unstable and can react with oxygen to generate H2O2, so that it is important to transfer it efficiently to LuxAB. Recently, LuxG has been identified as a NADH:FMN oxidoreductase that supplies FMNH(-) to luciferase in vivo. In this report, the mode of transfer of FMNH(-) between LuxG from Photobacterium leiognathi TH1 and LuxABs from both P. leiognathi TH1 and Vibrio campbellii (PlLuxAB and VcLuxAB, respectively) was investigated using single-mixing and double-mixing stopped-flow spectrophotometry. The oxygenase component of p-hydroxyphenylacetate hydroxylase (C2) from Acinetobacter baumannii, which has no structural similarity to LuxAB, was used to measure the kinetics of release of FMNH(-) from LuxG. With all FMNH(-) acceptors used (C2, PlLuxAB, and VcLuxAB), the kinetics of FMN reduction on LuxG were the same, showing that LuxG releases FMNH(-) with a rate constant of 4.5-6 s(-1). Our data showed that the kinetics of binding of FMNH(-)to PlLuxAB and VcLuxAB and the subsequent reactions with oxygen were the same with either free FMNH(-) or FMNH(-) generated in situ by LuxG. These results strongly suggest that no complexes between LuxG and the various species are necessary to transfer FMNH(-) to the acceptors. The kinetics of the overall reactions and the individual rate constants correlate well with a free diffusion model for the transfer of FMNH(-) from LuxG to either LuxAB.
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Affiliation(s)
- Ruchanok Tinikul
- Mahidol University , Nakhonsawan Campus, Nakhonsawan 60130, Thailand
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47
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Thoden JB, Branch MC, Zimmer AL, Bruender NA, Holden HM. Active site architecture of a sugar N-oxygenase. Biochemistry 2013; 52:3191-3. [PMID: 23621882 DOI: 10.1021/bi400407x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
KijD3 is a flavin-dependent N-oxygenase implicated in the formation of the nitro-containing sugar d-kijanose, found attached to the antibiotic kijanimicin. For this investigation, the structure of KijD3 in complex with FMN and its dTDP-sugar substrate was solved to 2.1 Å resolution. In contrast to the apoenzyme structure, the C-terminus of the protein becomes ordered and projects into the active site cleft [Bruender, N. A., Thoden, J. B., and Holden, H. M. (2010) Biochemistry 49, 3517-3524]. The amino group of the dTDP-aminosugar that is oxidized is located 4.9 Å from C4a of the flavin ring. The model provides a molecular basis for understanding the manner in which KijD3 catalyzes its unusual chemical transformation.
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Affiliation(s)
- James B Thoden
- Department of Biochemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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48
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Form follows function: structural and catalytic variation in the class a flavoprotein monooxygenases. Int J Mol Sci 2012; 13:15601-39. [PMID: 23443084 PMCID: PMC3546652 DOI: 10.3390/ijms131215601] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 11/08/2012] [Accepted: 11/09/2012] [Indexed: 12/02/2022] Open
Abstract
Flavoprotein monooxygenases (FPMOs) exhibit an array of mechanistic solutions to a common chemical objective; the monooxygenation of a target substrate. Each FPMO efficiently couples reduction of a flavin cofactor by NAD(P)H to oxygenation of the target substrate via a (hydro)peroxyflavin intermediate. This purpose of this review is to describe in detail the Class A flavoprotein hydroxylases (FPMO) in the context of the other FPMO classes (B–F). Both one and two component FPMOs are found in nature. Two-component enzymes require, in addition to the monooxygenase, the involvement of a reductase that first catalyzes the reduction of the flavin by NAD(P)H. The Class A and B FPMOs are single-component and manage to orchestrate the same net reaction within a single peptide. The Class A enzymes have, by some considerable margin, the most complete research record. These enzymes use choreographed movements of the flavin ring that facilitate access of the organic substrates to the active site, provide a means for interaction of NADPH with the flavin, offer a mechanism to sequester the dioxygen reduction chemistry from solvent and a means to release the product. The majority of the discrete catalytic events of the catalytic cycle can be observed directly in exquisite detail using spectrophotometric kinetic methods and many of the key mechanistic conclusions are further supported by structural data. This review attempts to compile each of the key observations made for both paradigm and newly discovered examples of Class A FPMOs into a complete catalytic description of one enzymatic turnover.
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49
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The fusion Vibrio campbellii luciferase as a eukaryotic gene reporter. J Biotechnol 2012; 162:346-53. [PMID: 23000378 DOI: 10.1016/j.jbiotec.2012.08.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 08/27/2012] [Accepted: 08/30/2012] [Indexed: 11/21/2022]
Abstract
Bacterial luciferase from Vibrio campbellii is a thermostable enzyme with an in vitro thermal inactivation half-life of ~1020 min at 37°C. The enzyme also binds tightly to reduced FMN. In this study, a V. campbellii fusion luciferase construct in which the α and β subunits are linked with a decapeptide was made and characterized. In general, the overall enzymatic properties of the two enzymes are similar. Expression of the enzymes in Escherichia coli demonstrated that the V. campbellii fusion luciferase emits less light than the native luciferase, but still emits a much greater amount of light than native luciferase from Vibrio harveyi and Photobacterium leiognathi TH1. The intensity of light emitted by the V. campbellii fusion luciferase was more than 80-fold greater than that from the V. harveyi native luciferase when expressed at 37°C. Biochemical characterization has shown that the V. campbellii fusion luciferase also retains a high binding affinity for reduced flavin mononucleotide and high thermostability. The levels of bioluminescence emitted by the V. campbellii fusion luciferase expressed in HEK293T cells reached ~1×10(6) Relative Light Units/mg total protein. These findings suggest that the V. campbellii fusion luciferase is a promising candidate for further development as a luciferase-based reporter for eukaryotic systems.
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50
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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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