1
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Zubova E, Pokluda A, Dvořáková H, Krupička M, Cibulka R. Exploring the Reactivity of Flavins with Nucleophiles Using a Theoretical and Experimental Approach. Chempluschem 2024; 89:e202300547. [PMID: 38064649 DOI: 10.1002/cplu.202300547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 11/30/2023] [Indexed: 01/13/2024]
Abstract
Covalent adducts of flavin cofactors with nucleophiles play an important role in non-canonical function of flavoenzymes as well as in flavin-based catalysis. Herein, the interaction of flavin derivatives including substituted flavins (isoalloxazines), 1,10-ethylene-bridged flavinium salts, and non-substituted alloxazine and deazaflavin with selected nucleophiles was investigated using an experimental and computational approach. Triphenylphosphine or trimethylphosphine, 1-nitroethan-1-ide, and methoxide were selected as representatives of neutral soft, anionic soft, and hard nucleophiles, respectively. The interactions were investigated using UV/Vis and 1H NMR spectroscopy as well as by DFT calculations. The position of nucleophilic attack estimated using the calculated Gibbs free energy values was found to correspond with the experimental data, favouring the addition of phosphine and 1-nitroethan-1-ide into position N(5) and methoxide into position C(10a) of 1,10-ethylene-bridged flavinium salts. The calculated Gibbs free energy values were found to correlate with the experimental redox potentials of the flavin derivatives tested. These findings can be utilized as valuable tools for the design of artificial flavin-based catalytic systems or investigating the mechanism of flavoenzymes.
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Affiliation(s)
- Ekaterina Zubova
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28, Prague, Czech Republic
| | - Adam Pokluda
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28, Prague, Czech Republic
| | - Hana Dvořáková
- Central Laboratories, University of Chemistry and Technology, Prague, Technická 5, 166 28, Prague, Czech Republic
| | - Martin Krupička
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28, Prague, Czech Republic
| | - Radek Cibulka
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28, Prague, Czech Republic
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2
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Mondal A, Roy P, Carrannanto J, Datar PM, DiRocco DJ, Hunter K, Marsh ENG. Surveying the scope of aromatic decarboxylations catalyzed by prenylated-flavin dependent enzymes. Faraday Discuss 2024. [PMID: 38837123 DOI: 10.1039/d4fd00006d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
The prenylated-flavin mononucleotide-dependent decarboxylases (also known as UbiD-like enzymes) are the most recently discovered family of decarboxylases. The modified flavin facilitates the decarboxylation of unsaturated carboxylic acids through a novel mechanism involving 1,3-dipolar cyclo-addition chemistry. UbiD-like enzymes have attracted considerable interest for biocatalysis applications due to their ability to catalyse (de)carboxylation reactions on a broad range of aromatic substrates at otherwise unreactive carbon centres. There are now ∼35 000 protein sequences annotated as hypothetical UbiD-like enzymes. Sequence similarity network analyses of the UbiD protein family suggests that there are likely dozens of distinct decarboxylase enzymes represented within this family. Furthermore, many of the enzymes so far characterized can decarboxylate a broad range of substrates. Here we describe a strategy to identify potential substrates of UbiD-like enzymes based on detecting enzyme-catalysed solvent deuterium exchange into potential substrates. Using ferulic acid decarboxylase (FDC) as a model system, we tested a diverse range of aromatic and heterocyclic molecules for their ability to undergo enzyme-catalysed H/D exchange in deuterated buffer. We found that FDC catalyses H/D exchange, albeit at generally very low levels, into a wide range of small, aromatic molecules that have little resemblance to its physiological substrate. In contrast, the sub-set of aromatic carboxylic acids that are substrates for FDC-catalysed decarboxylation is much smaller. We discuss the implications of these findings for screening uncharacterized UbiD-like enzymes for novel (de)carboxylase activity.
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Affiliation(s)
- Anushree Mondal
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
| | - Pronay Roy
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
| | - Jaclyn Carrannanto
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
| | - Prathamesh M Datar
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
| | - Daniel J DiRocco
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
| | - Katherine Hunter
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
| | - E Neil G Marsh
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA
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3
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Quaye JA, Wood KE, Snelgrove C, Ouedraogo D, Gadda G. An active site mutation induces oxygen reactivity in D-arginine dehydrogenase: A case of superoxide diverting protons. J Biol Chem 2024; 300:107381. [PMID: 38762175 PMCID: PMC11193025 DOI: 10.1016/j.jbc.2024.107381] [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: 04/12/2024] [Revised: 05/09/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024] Open
Abstract
Enzymes are potent catalysts that increase biochemical reaction rates by several orders of magnitude. Flavoproteins are a class of enzymes whose classification relies on their ability to react with molecular oxygen (O2) during catalysis using ionizable active site residues. Pseudomonas aeruginosa D-arginine dehydrogenase (PaDADH) is a flavoprotein that oxidizes D-arginine for P. aeruginosa survival and biofilm formation. The crystal structure of PaDADH reveals the interaction of the glutamate 246 (E246) side chain with the substrate and at least three other active site residues, establishing a hydrogen bond network in the active site. Additionally, E246 likely ionizes to facilitate substrate binding during PaDADH catalysis. This study aimed to investigate how replacing the E246 residue with leucine affects PaDADH catalysis and its ability to react with O2 using steady-state kinetics coupled with pH profile studies. The data reveal a gain of O2 reactivity in the E246L variant, resulting in a reduced flavin semiquinone species and superoxide (O2•-) during substrate oxidation. The O2•- reacts with active site protons, resulting in an observed nonstoichiometric slope of 1.5 in the enzyme's log (kcat/Km) pH profile with D-arginine. Adding superoxide dismutase results in an observed correction of the slope to 1.0. This study demonstrates how O2•- can alter the slopes of limbs in the pH profiles of flavin-dependent enzymes and serves as a model for correcting nonstoichiometric slopes in elucidating reaction mechanisms of flavoproteins.
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Affiliation(s)
- Joanna A Quaye
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Kendall E Wood
- Biology Department, Morehouse College, Atlanta, Georgia, USA
| | - Claire Snelgrove
- The Gwinnett School of Mathematics, Science, and Technology, Lawrenceville, Georgia, USA
| | - Daniel Ouedraogo
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA; Department of Biology, Georgia State University, Atlanta, Georgia, USA; Department of the Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia, USA.
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4
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Rehpenn A, Hindelang S, Truong KN, Pöthig A, Storch G. Enhancing Flavins Photochemical Activity in Hydrogen Atom Abstraction and Triplet Sensitization through Ring-Contraction. Angew Chem Int Ed Engl 2024; 63:e202318590. [PMID: 38339882 DOI: 10.1002/anie.202318590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 01/30/2024] [Accepted: 02/01/2024] [Indexed: 02/12/2024]
Abstract
The isoalloxazine heterocycle of flavin cofactors reacts with various nucleophiles to form covalent adducts with important functions in enzymes. Molecular flavin models allow for the characterization of such adducts and the study of their properties. A fascinating set of reactions occurs when flavins react with hydroxide base, which leads to imidazolonequinoxalines, ring-contracted flavins, with so far unexplored activity. We report a systematic study of the photophysical properties of this new chromophore by absorption and emission spectroscopy as well as cyclic voltammetry. Excited, ring-contracted flavins are significantly stronger hydrogen atom abstractors when compared to the parent flavins, which allowed the direct trifluoromethylthiolation of aliphatic methine positions (bond dissociation energy (BDE) of 400.8 kJ mol-1). In an orthogonal activity, their increased triplet energy (E(S0←T1)=244 kJ mol-1) made sensitized reactions possible which exceeded the power of standard flavins. Combining both properties, ring-contracted flavin catalysts enabled the one-pot, five-step transformation of α-tropolone into trans-3,4-disubstituted cyclopentanones. We envision this new class of flavin-derived chromophores to open up new modes of reactivity that are currently impossible with unmodified flavins.
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Affiliation(s)
- Andreas Rehpenn
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Stephan Hindelang
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Khai-Nghi Truong
- Rigaku Europe SE, Hugenottenallee 167, 63263, Neu-Isenburg, Germany
| | - Alexander Pöthig
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
| | - Golo Storch
- Technical University of Munich (TUM), School of Natural Sciences and Catalysis Research Center (CRC), Lichtenbergstr. 4, 85747, Garching, Germany
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5
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Datar PM, Joshi SY, Deshmukh SA, Marsh ENG. Probing the role of protein conformational changes in the mechanism of prenylated-FMN-dependent phenazine-1-carboxylic acid decarboxylase. J Biol Chem 2024; 300:105621. [PMID: 38176649 PMCID: PMC10850782 DOI: 10.1016/j.jbc.2023.105621] [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: 08/21/2023] [Revised: 11/30/2023] [Accepted: 12/27/2023] [Indexed: 01/06/2024] Open
Abstract
Phenazine-1-carboxylic acid decarboxylase (PhdA) is a prenylated-FMN-dependent (prFMN) enzyme belonging to the UbiD family of decarboxylases. Many UbiD-like enzymes catalyze (de)carboxylation reactions on aromatic rings and conjugated double bonds and are potentially valuable industrial catalysts. We have investigated the mechanism of PhdA using a slow turnover substrate, 2,3-dimethylquinoxaline-5-carboxylic acid (DQCA). Detailed analysis of the pH dependence and solvent deuterium isotope effects associated with the reaction uncovered unusual kinetic behavior. At low substrate concentrations, a substantial inverse solvent isotope effect (SIE) is observed on Vmax/KM of ∼ 0.5 when reaction rates of DQCA in H2O and D2O are compared. Under the same conditions, a normal SIE of 4.15 is measured by internal competition for proton transfer to the product. These apparently contradictory results indicate that the SIE values report on different steps in the mechanism. A proton inventory analysis of the reaction under Vmax/KM and Vmax conditions points to a "medium effect" as the source of the inverse SIE. Molecular dynamics simulations of the effect of D2O on PhdA structure support that D2O reduces the conformational lability of the enzyme and results in a more compact structure, akin to the active, "closed" conformer observed in crystal structures of some UbiD-like enzymes. Consistent with the simulations, PhdA was found to be more stable in D2O and to bind DQCA more tightly, leading to the observed rate enhancement under Vmax/KM conditions.
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Affiliation(s)
- Prathamesh M Datar
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA
| | - Soumil Y Joshi
- Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
| | - Sanket A Deshmukh
- Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
| | - E Neil G Marsh
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, USA.
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6
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Turlington ZR, Vaz Ferreira de Macedo S, Perry K, Belsky SL, Faust JA, Snider MJ, Hicks KA. Ligand bound structure of a 6-hydroxynicotinic acid 3-monooxygenase provides mechanistic insights. Arch Biochem Biophys 2024; 752:109859. [PMID: 38104959 DOI: 10.1016/j.abb.2023.109859] [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: 10/31/2023] [Revised: 12/08/2023] [Accepted: 12/11/2023] [Indexed: 12/19/2023]
Abstract
6-Hydroxynicotinic acid 3-monooxygenase (NicC) is a bacterial enzyme involved in the degradation of nicotinic acid. This enzyme is a Class A flavin-dependent monooxygenase that catalyzes a unique decarboxylative hydroxylation. The unliganded structure of this enzyme has previously been reported and studied using steady- and transient-state kinetics to support a comprehensive kinetic mechanism. Here we report the crystal structure of the H47Q NicC variant in both a ligand-bound (solved to 2.17 Å resolution) and unliganded (1.51 Å resolution) form. Interestingly, in the liganded form, H47Q NicC is bound to 2-mercaptopyridine (2-MP), a contaminant present in the commercial stock of 6-mercaptopyridine-3-carboxylic acid(6-MNA), a substrate analogue. 2-MP binds weakly to H47Q NicC and is not a substrate for the enzyme. Based on kinetic and thermodynamic characterization, we have fortuitously captured a catalytically inactive H47Q NicC•2-MP complex in our crystal structure. This complex reveals interesting mechanistic details about the reaction catalyzed by 6-hydroxynicotinic acid 3-monooxygenase.
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Affiliation(s)
- Zachary R Turlington
- Department of Chemistry, State University of New York at Cortland, Cortland, NY, 13045, United States
| | | | - Kay Perry
- NE-CAT and Department of Chemistry and Chemical Biology, Cornell University, Argonne National Laboratory, Argonne, IL, United States
| | - Sam L Belsky
- Department of Chemistry, The College of Wooster, Wooster, OH, 44691, United States
| | - Jennifer A Faust
- Department of Chemistry, The College of Wooster, Wooster, OH, 44691, United States
| | - Mark J Snider
- Department of Chemistry, The College of Wooster, Wooster, OH, 44691, United States
| | - Katherine A Hicks
- Department of Chemistry, State University of New York at Cortland, Cortland, NY, 13045, United States.
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7
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Wang B, Wang Y, Zhang Z, Wen X, Xi Z. Insight into the Role of an α-Helix Cluster in Protoporphyrinogen IX Oxidase. Biochemistry 2024. [PMID: 38285491 DOI: 10.1021/acs.biochem.3c00508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Protoporphyrinogen IX oxidase (PPO) is the last common enzyme in chlorophyll and heme biosynthesis pathways. In humans, point mutations on PPO are responsible for the dominantly inherited disorder disease variegate porphyria (VP). It is found that several VP-causing mutation sites are located on an α-helix cluster (consisting of α-5, α-6, and α-7 helix, named the G169 helix cluster) of human PPO, although these mutation sites are outside the active site of the human PPO. In this work, we investigated the role of the G169 helix cluster via site-directed mutagenesis, enzymatic kinetics, and computational studies. Kinetic studies showed that mutations on the G169 helix cluster affect the activity of PPO. The MD simulation showed that mutations on the G169 helix cluster reduced the activity of PPO by affecting the proper orientation of substrate protoporphyrinogen within the active site of PPO and possibly the dipole moment of the G169 helix cluster. Moreover, the mutation abolished the interaction between the mutated site and other residues, thus affecting the secondary structure and hydrogen bond interactions within the G169 helix cluster. These results indicated that the integrity of the G169 helix cluster is important for the stabilization of protoporphyrinogen within the active site of PPO to facilitate the interaction between protoporphyrinogen and cofactor FAD and provide a proper electrostatic environment for the activity of PPO. Our result provides new insight into understanding the relationship between the structure and function of PPO.
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Affiliation(s)
- Baifan Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Yiban Wang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Zijuan Zhang
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Xin Wen
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
| | - Zhen Xi
- State Key Laboratory of Elemento-Organic Chemistry and Department of Chemical Biology, National Pesticide Engineering Research Center (Tianjin), Nankai University, 94 Weijin Road, Tianjin 300071, China
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8
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Tjallinks G, Boverio A, Jager AW, Kaya SG, Mattevi A, Fraaije MW. Efficient Oxidation of 5-Hydroxymethylfurfural Using a Flavoprotein Oxidase from the Honeybee Apis mellifera. Chembiochem 2023; 24:e202300588. [PMID: 37800383 DOI: 10.1002/cbic.202300588] [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: 08/21/2023] [Revised: 10/04/2023] [Accepted: 10/05/2023] [Indexed: 10/07/2023]
Abstract
The chemical 5-hydroxymethylfurfural (HMF) can be derived from lignocellulose and is an interesting bio-based platform chemical as it has the potential to be transformed into numerous valuable building blocks such as the polymer-precursor 2,5-diformylfuran (DFF). To date, only a few oxidases acting on HMF are known and by sampling atypical species, we discovered a novel flavin-dependent oxidoreductase from the honeybee Apis mellifera (beeHMFO). The enzyme can perform the chemoselective oxidation of HMF to DFF but can also readily accept other aromatic alcohols as substrates. The function of the enzyme may well be the antimicrobial generation of hydrogen peroxide using HMF, which is very abundant in honey. The discovery of this insect-derived flavoprotein oxidase holds promising potential in the synthesis of renewable products and demonstrates that insects can be an interesting source of novel biocatalysts.
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Affiliation(s)
- Gwen Tjallinks
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen (The, Netherlands
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, Pavia, Italy
| | - Alessandro Boverio
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen (The, Netherlands
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, Pavia, Italy
| | - Amarins W Jager
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen (The, Netherlands
| | - Saniye G Kaya
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen (The, Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 9, Pavia, Italy
| | - Marco W Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, Groningen (The, Netherlands
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9
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Tong Y, Kaya SG, Russo S, Rozeboom HJ, Wijma HJ, Fraaije MW. Fixing Flavins: Hijacking a Flavin Transferase for Equipping Flavoproteins with a Covalent Flavin Cofactor. J Am Chem Soc 2023; 145:27140-27148. [PMID: 38048072 PMCID: PMC10722498 DOI: 10.1021/jacs.3c12009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 12/05/2023]
Abstract
Most flavin-dependent enzymes contain a dissociable flavin cofactor. We present a new approach for installing in vivo a covalent bond between a flavin cofactor and its host protein. By using a flavin transferase and carving a flavinylation motif in target proteins, we demonstrate that "dissociable" flavoproteins can be turned into covalent flavoproteins. Specifically, four different flavin mononucleotide-containing proteins were engineered to undergo covalent flavinylation: a light-oxygen-voltage domain protein, a mini singlet oxygen generator, a nitroreductase, and an old yellow enzyme-type ene reductase. Optimizing the flavinylation motif and expression conditions led to the covalent flavinylation of all four flavoproteins. The engineered covalent flavoproteins retained function and often exhibited improved performance, such as higher thermostability or catalytic performance. The crystal structures of the designed covalent flavoproteins confirmed the designed threonyl-phosphate linkage. The targeted flavoproteins differ in fold and function, indicating that this method of introducing a covalent flavin-protein bond is a powerful new method to create flavoproteins that cannot lose their cofactor, boosting their performance.
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Affiliation(s)
- Yapei Tong
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Saniye G. Kaya
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Sara Russo
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Henriette J. Rozeboom
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Hein J. Wijma
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
| | - Marco W. Fraaije
- Molecular Enzymology Group, University of Groningen, Nijenborgh 4, 9747
AG Groningen, The
Netherlands
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10
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Bou-Nader C, Pecqueur L, de Crécy-Lagard V, Hamdane D. Integrative Approach to Probe Alternative Redox Mechanisms in RNA Modifications. Acc Chem Res 2023; 56:3142-3152. [PMID: 37916403 PMCID: PMC10999249 DOI: 10.1021/acs.accounts.3c00418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2023]
Abstract
RNA modifications found in most RNAs, particularly in tRNAs and rRNAs, reveal an abundance of chemical alterations of nucleotides. Over 150 distinct RNA modifications are known, emphasizing a remarkable diversity of chemical moieties in RNA molecules. These modifications play pivotal roles in RNA maturation, structural integrity, and the fidelity and efficiency of translation processes. The catalysts responsible for these modifications are RNA-modifying enzymes that use a striking array of chemistries to directly influence the chemical landscape of RNA. This diversity is further underscored by instances where the same modification is introduced by distinct enzymes that use unique catalytic mechanisms and cofactors across different domains of life. This phenomenon of convergent evolution highlights the biological importance of RNA modification and the vast potential within the chemical repertoire for nucleotide alteration. While shared RNA modifications can hint at conserved enzymatic pathways, a major bottleneck is to identify alternative routes within species that possess a modified RNA but are devoid of known RNA-modifying enzymes. To address this challenge, a combination of bioinformatic and experimental strategies proves invaluable in pinpointing new genes responsible for RNA modifications. This integrative approach not only unveils new chemical insights but also serves as a wellspring of inspiration for biocatalytic applications and drug design. In this Account, we present how comparative genomics and genome mining, combined with biomimetic synthetic chemistry, biochemistry, and anaerobic crystallography, can be judiciously implemented to address unprecedented and alternative chemical mechanisms in the world of RNA modification. We illustrate these integrative methodologies through the study of tRNA and rRNA modifications, dihydrouridine, 5-methyluridine, queuosine, 8-methyladenosine, 5-carboxymethylamino-methyluridine, or 5-taurinomethyluridine, each dependent on a diverse array of redox chemistries, often involving organic compounds, organometallic complexes, and metal coenzymes. We explore how vast genome and tRNA databases empower comparative genomic analyses and enable the identification of novel genes that govern RNA modification. Subsequently, we describe how the isolation of a stable reaction intermediate can guide the synthesis of a biomimetic to unveil new enzymatic pathways. We then discuss the usefulness of a biochemical "shunt" strategy to study catalytic mechanisms and to directly visualize reactive intermediates bound within active sites. While we primarily focus on various RNA-modifying enzymes studied in our laboratory, with a particular emphasis on the discovery of a SAM-independent methylation mechanism, the strategies and rationale presented herein are broadly applicable for the identification of new enzymes and the elucidation of their intricate chemistries. This Account offers a comprehensive glimpse into the evolving landscape of RNA modification research and highlights the pivotal role of integrated approaches to identify novel enzymatic pathways.
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Affiliation(s)
- Charles Bou-Nader
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
| | - Ludovic Pecqueur
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
| | - Valérie de Crécy-Lagard
- Department of Microbiology and Cell Science, University of Florida, Gainesville, Florida, 32611, USA
- University of Florida, Genetics Institute, Gainesville, Florida, 32610, USA
| | - Djemel Hamdane
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France
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11
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Mangkalee M, Oonanant W, Aonbangkhen C, Pimviriyakul P, Tinikul R, Chaiyen P, Insin N, Sucharitakul J. Reaction mechanism and kinetics of the two-component flavoprotein dimethyl sulfone monooxygenase system: Using hydrogen peroxide for monooxygenation and substrate cleavage. FEBS J 2023; 290:5171-5195. [PMID: 37522421 DOI: 10.1111/febs.16916] [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: 05/30/2023] [Revised: 07/14/2023] [Accepted: 07/28/2023] [Indexed: 08/01/2023]
Abstract
The dimethyl sulfone monooxygenase system is a two-component flavoprotein, catalyzing the monooxygenation of dimethyl sulfone (DMSO2 ) by oxidative cleavage producing methanesulfinate and formaldehyde. The reductase component (DMSR) is a flavoprotein with FMN as a cofactor, catalyzing flavin reduction using NADH. The monooxygenase (DMSMO) uses reduced flavin from the reductase and oxygen for substrate monooxygenation. DMSMO can bind to FMN and FMNH- with a Kd of 17.4 ± 0.9 μm and 4.08 ± 0.8 μm, respectively. The binding of FMN to DMSMO is required prior to binding DMSO2 . This also applies to the fast binding of reduced FMN to DMSMO followed by DMSO2 . Substituting reduced DMSR with FMNH- demonstrated the same oxidation kinetics, indicating that FMNH- from DMSR was transferred to DMSMO. The oxidation of FMNH- :DMSMO, with and without DMSO2 did not generate any flavin adducts for monooxygenation. Therefore, H2 O2 is likely to be the reactive agent to attack the substrate. The H2 O2 assay results demonstrated production of H2 O2 from the oxidation of FMNH- :DMSMO, whereas H2 O2 was not detected in the presence of DMSO2 , confirming H2 O2 utilization. The rate constant for methanesulfinate formation determined from rapid quenched flow and the rate constant for flavin oxidation were similar, indicating that H2 O2 rapidly reacts with DMSO2 , with flavin oxidation as the rate-limiting step. This is the first report of the kinetic mechanisms of both components using rapid kinetics and of a method for methanesulfinate detection using LC-MS.
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Affiliation(s)
- Montisa Mangkalee
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Research Unit in Integrative Immuno-Microbial Biochemistry and Bioresponsive Nanomaterials, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Worrapoj Oonanant
- Department of Basic Medical Science, Faculty of Medicine Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand
| | - Chanat Aonbangkhen
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Center of Excellence in Natural Products Chemistry (CENP), Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
| | - Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Ruchanok Tinikul
- Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Pimchai Chaiyen
- School of Biomolecular Science and Engineering, Vidyasirimedhi Institute of Science and Technology (VISTEC), Rayong, Thailand
| | - Numpon Insin
- Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok, Thailand
- Research Unit in Integrative Immuno-Microbial Biochemistry and Bioresponsive Nanomaterials, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
| | - Jeerus Sucharitakul
- Department of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
- Skeletal Disorders Research Unit, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand
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12
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Kozyryev A, Boucher PA, Quiñones-Jurgensen CM, Rokita SE. The 2'-hydroxy group of flavin mononucleotide influences the catalytic function and promiscuity of the flavoprotein iodotyrosine dehalogenase. RSC Chem Biol 2023; 4:698-705. [PMID: 37654510 PMCID: PMC10467613 DOI: 10.1039/d3cb00094j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Accepted: 08/03/2023] [Indexed: 09/02/2023] Open
Abstract
The isoalloxazine ring system of the flavin cofactor is responsible for much of the catalytic power and diversity associated with flavoproteins. While the specificity of these enzymes is greatly influenced by the surrounding protein environment, the ribityl group of the cofactor may also participate in stabilizing transient intermediates formed by substrates and flavin. A conserved interaction between the phenolate oxygen of l-iodotyrosine and the 2'-hydroxy group of flavin mononucleotide (FMN) bound to iodotyrosine deiodianase (IYD) implied such a contribution to catalysis. Reconstitution of this deiodinase with 2'-deoxyflavin mononucleotide (2'-deoxyFMN) decreased the overall catalytic efficiency of l-iodotyrosine dehalogenation (kcat/Km) by more than 5-fold but increased kcat by over 2-fold. These affects are common to human IYD and its homolog from Thermotoga neapolitana and are best explained by an ability of the 2'-hydroxy group of FMN to stabilize association of the substrate in its phenolate form. Loss of this 2'-hydroxy group did not substantially affect the formation of the one electron reduced semiquinone form of FMN but its absence released constraints that otherwise suppresses the ability of IYD to promote hydride transfer as measured by a competing nitroreductase activity. Generation of IYD containing 2'-deoxyFMN also removed steric constraints that had previously limited the use of certain mechanistic probes. For example, l-O-methyl iodotyrosine could be accommodated in the active site lacking the 2'-hydroxy of FMN and shown to be inert to dehalogenation as predicted from a mechanism requiring ketonization of the phenolic oxygen. In the future, ancillary sites within a cofactor should now be considered when engineering new functions within existing protein architectures as demonstrated by the ability of IYD to promote nitroreduction after loss of the 2'-hydroxy group of FMN.
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Affiliation(s)
- Anton Kozyryev
- Department of Chemistry, Johns Hopkins University 3400 N. Charles St. Maryland 21218 USA +1-410-516-5793
| | - Petrina A Boucher
- Department of Chemistry, Johns Hopkins University 3400 N. Charles St. Maryland 21218 USA +1-410-516-5793
| | - Carla M Quiñones-Jurgensen
- Department of Chemistry, Johns Hopkins University 3400 N. Charles St. Maryland 21218 USA +1-410-516-5793
| | - Steven E Rokita
- Department of Chemistry, Johns Hopkins University 3400 N. Charles St. Maryland 21218 USA +1-410-516-5793
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13
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Pimviriyakul P, Kapaothong Y, Tangsupatawat T. Heterologous Expression and Characterization of a Full-length Protozoan Nitroreductase from Leishmania orientalis isolate PCM2. Mol Biotechnol 2023; 65:556-569. [PMID: 36042106 DOI: 10.1007/s12033-022-00556-3] [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: 06/29/2022] [Accepted: 08/22/2022] [Indexed: 11/25/2022]
Abstract
Leishmaniasis, a parasitic disease found in parts of the tropics and subtropics, is caused by Leishmania protozoa infection. Nitroreductases (NTRs), enzymes involved in nitroaromatic prodrug activation, are attractive targets for leishmaniasis treatment development. In this study, a full-length recombinant NTR from the Leishmania orientalis isolate PCM2 (LoNTR), which causes severe leishmaniasis in Thailand, was successfully expressed in soluble form using chaperone co-expression in Escherichia coli BL21(DE3). The purified histidine-tagged enzyme (His6-LoNTR) had a subunit molecular mass of 36 kDa with no cofactor bound; however, the addition of exogenous flavin (either FMN or FAD) readily increased its enzyme activity. Bioinformatics analysis found that the unique N-terminal sequences of LoNTR is only present in Leishmania where the addition of this region might result in the loss of flavin binding. Either NADH or NADPH can serve as an electron donor to transfer electrons to nitrofurazone; however, NADPH was preferred. Molecular oxygen was identified as an additional electron acceptor resulting in wasteful electrons from NADPH for the main catalysis. Steady-state kinetic experiments revealed a ping-pong mechanism for His6-LoNTR with Km,NADPH, Km,NFZ, and kcat of 28 µM, 68 µM, and 0.84 min-1, respectively. Besides nitroreductase activity, His6-LoNTR also has the ability to reduce quinone derivatives. The properties of full-length His6-LoNTR were different from previously reported protozoa and bacterial NTRs in many respects. This study provides information of NTR catalysis to be developed as a potential future therapeutic target to treat leishmaniasis.
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Affiliation(s)
- Panu Pimviriyakul
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand.
| | - Yuvarun Kapaothong
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Theerapat Tangsupatawat
- Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
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14
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Pokluda A, Zubova E, Chudoba J, Krupička M, Cibulka R. Catalytic artificial nitroalkane oxidases - a way towards organocatalytic umpolung. Org Biomol Chem 2023; 21:2768-2774. [PMID: 36919409 DOI: 10.1039/d3ob00101f] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Nitroalkane oxidases (NAOs) are flavoenzymes that catalyse the oxidation of nitroalkanes to their corresponding carbonyl compounds while producing nitrite anions. Herein, we present an artificial catalytic system using flavins or ethylene-bridged flavinium salts that works via an NAO-like process. Under conditions optimised in terms of solvent, base, temperature and oxygen pressure, primary nitroalkanes were transformed to aldehydes. In our system, aldehydes immediately reacted with other nitroalkane molecules to form β-nitroalcohols. The reduced flavin catalyst was re-oxidised by oxygen. An alternative mechanism towards β-nitroalcohols via 5-(2-nitrobutyl)-1,5-dihydroflavin was suggested through quantum chemical calculations and by trapping and characterising this dihydroflavin intermediate. Interestingly, 5-(2-nitrobutyl)-1,5-dihydroflavin is an analogue of the flavin adenine dinucleotide adduct previously observed in an NAO X-ray structure. In both mechanistic pathways, flavin-5-iminium species is formed by nitroalkanide addition to flavin. This process represents flavin-based umpolung of an original donor to an acceptor.
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Affiliation(s)
- Adam Pokluda
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic.
| | - Ekaterina Zubova
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic.
| | - Josef Chudoba
- Central Laboratories, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Martin Krupička
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic.
| | - Radek Cibulka
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Technická 5, 166 28 Prague, Czech Republic.
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15
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Van Galen CJ, Pauszek RF, Koder RL, Stanley RJ. Flavin Charge Redistribution upon Optical Excitation Is Independent of Solvent Polarity. J Phys Chem B 2023; 127:661-672. [PMID: 36649202 DOI: 10.1021/acs.jpcb.2c07266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Flavin absorption spectra encode molecular details of the flavin's local environment through coupling of local electric fields with the chromophore's charge redistribution upon optical excitation. Translating experimentally measured field-tuned transition energies to local electric field magnitudes and directions across a wide range of field magnitudes requires that the charge redistribution be independent of the local field. We have measured the charge redistribution upon optical excitation of the derivatized flavin TPARF in the non-hydrogen-bonding, nonpolar solvent toluene, with and without a tridentate hydrogen-bonding ligand, DBAP, using electronic Stark spectroscopy. These measurements were interpreted using TD-DFT finite field and difference density calculations. In comparing our present results to previous Stark spectroscopic analyses of flavin in more polar solvents, we conclude that flavin charge redistribution upon optical excitation is independent of solvent polarity, indicating that dependence of flavin transition energies on local field magnitude is linear with local field magnitude.
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Affiliation(s)
- Cornelius J Van Galen
- Department of Chemistry, Temple University, 1901 N. 13th St., 250B Beury Hall, Philadelphia, Pennsylvania19122, United States
| | - Raymond F Pauszek
- Department of Chemistry, Temple University, 1901 N. 13th St., 250B Beury Hall, Philadelphia, Pennsylvania19122, United States
| | - Ronald L Koder
- Department of Physics, The City College of New York, 1.308 CDI Bldg., 85 St. Nicholas Terrace, New York, New York10031, United States
| | - Robert J Stanley
- Department of Chemistry, Temple University, 1901 N. 13th St., 250B Beury Hall, Philadelphia, Pennsylvania19122, United States
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16
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Kaneshiro AK, Datar PM, Marsh ENG. Negative Cooperativity in the Mechanism of Prenylated-Flavin-Dependent Ferulic Acid Decarboxylase: A Proposal for a "Two-Stroke" Decarboxylation Cycle. Biochemistry 2023; 62:53-61. [PMID: 36521056 DOI: 10.1021/acs.biochem.2c00460] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Ferulic acid decarboxylase (FDC) catalyzes the reversible carboxylation of various substituted phenylacrylic acids to produce the correspondingly substituted styrenes and CO2. FDC is a member of the UbiD family of enzymes that use prenylated-FMN (prFMN) to catalyze decarboxylation reactions on aromatic rings and C-C double bonds. Although a growing number of prFMN-dependent enzymes have been identified, the mechanism of the reaction remains poorly understood. Here, we present a detailed pre-steady-state kinetic analysis of the FDC-catalyzed reaction of prFMN with both styrene and phenylacrylic acid. Based on the pattern of reactivity observed, we propose a "two-stroke" kinetic model in which negative cooperativity between the two subunits of the FDC homodimer plays an important and previously unrecognized role in catalysis. In this model, catalysis is initiated at the high-affinity active site, which reacts with phenylacrylate to yield, after decarboxylation, the covalently bound styrene-prFMN cycloadduct. In the second stage of the catalytic cycle, binding of the second substrate molecule to the low-affinity active site drives a conformational switch that interconverts the high-affinity and low-affinity active sites. This switching of affinity couples the energetically unfavorable cycloelimination of styrene from the first site with the energetically favorable cycloaddition and decarboxylation of phenylacrylate at the second site. We note as a caveat that, at this point, the complexity of the FDC kinetics leaves open other mechanistic interpretations and that further experiments will be needed to more firmly establish or refute our proposal.
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17
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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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18
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Rehpenn A, Walter A, Storch G. Molecular flavin catalysts for C-H functionalisation and derivatisation of dehydroamino acids. Chem Sci 2022; 13:14151-14156. [PMID: 36540823 PMCID: PMC9728571 DOI: 10.1039/d2sc04341f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/04/2022] [Indexed: 03/12/2024] Open
Abstract
In nature, the isoalloxazine heterocycle of flavin cofactors undergoes reversible covalent bond formation with a variety of different reaction partners. These intermediates play a crucial role inter alia as the signalling states and in selective catalysis reactions. In the organic laboratory, covalent adducts with a new carbon-carbon bond have been observed with photochemically excited flavins but have, so far, only been regarded as dead-end side products. We have identified a series of molecular flavins that form adducts resulting in a new C-C bond at the C4a-position through allylic C-H activation and dehydroamino acid oxidation. Typically, these reactions are of radical nature and a stepwise pathway is assumed. We could demonstrate that these adducts are no dead-end and that the labile C-C bond can be cleaved by adding the persistent radical TEMPO leading to flavin regeneration and alkoxyamine-functionalised substrates. Our method allows for the catalytic oxidation of dehydroamino acids (16 examples) and we show that the acylimine products serve as versatile starting points for diversification. The present results are envisioned to stimulate the design of further catalytic reactions involving intermediates at the flavin C4a-position and their reactivity towards metal complexes or other persistent organic radicals. Our method for dehydrobutyrine derivatisation is orthogonal to the currently used methods (i.e., nucleophilic attack or radical addition) and offers new perspectives for peptide natural product diversification.
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Affiliation(s)
- Andreas Rehpenn
- School of Natural Sciences and Catalysis Research Center (CRC), Technical University of Munich (TUM) Lichtenbergstr. 4 85747 Garching Germany
| | - Alexandra Walter
- School of Natural Sciences and Catalysis Research Center (CRC), Technical University of Munich (TUM) Lichtenbergstr. 4 85747 Garching Germany
| | - Golo Storch
- School of Natural Sciences and Catalysis Research Center (CRC), Technical University of Munich (TUM) Lichtenbergstr. 4 85747 Garching Germany
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19
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WANG M, ZHANG W, WANG N. Covalent flavoproteins: types, occurrence, biogenesis and catalytic mechanisms. Chin J Nat Med 2022; 20:749-760. [DOI: 10.1016/s1875-5364(22)60194-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Indexed: 11/03/2022]
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20
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Żaczek S, Dybala-Defratyka A. Unravelling interactions between active site residues and DMAP in the initial steps of prenylated flavin mononucleotide biosynthesis catalyzed by PaUbiX. Biochim Biophys Acta Gen Subj 2022; 1866:130247. [PMID: 36162732 DOI: 10.1016/j.bbagen.2022.130247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 09/15/2022] [Accepted: 09/20/2022] [Indexed: 10/14/2022]
Abstract
BACKGROUND Prenylated flavin mononucleotide (prFMN) is a recently discovered, heavily modified flavin compound. It is the only known cofactor that enables enzymatic 1,3-dipolar cycloaddition reactions. It is produced by enzymes from the UbiX family, from flavin mononucleotide and either dimethylallyl mono- or diphosphate. prFMN biosynthesis is currently reported to be initiated by protonation of the substrate by Glu140. METHODS Computational chemistry methods are applied herein - Constant pH MD, classical MD simulations, and QM cluster optimizations. RESULTS Glu140 competes for a single proton with Lys129 prior to prFMN biosynthesis, but it is the latter that adopted a protonated state. Once the prenyl-FMN adduct is formed, Glu140 occurs in a protonated state far more often, while the occupancy of protonated Lys129 does not change. Lys129, Glu140, and Arg122 seem to play a key role in either stabilizing or protonating DMAP phosphate group within the PaUbiX active site throughout initial steps of prFMN biosynthesis. CONCLUSIONS The role of Lys129 in the functioning of PaUbiX is reported for the first time. Glu140 is unlikely to act as a proton donor in prFMN biosynthesis. Instead, Lys129 and Arg122 fulfil this role. Glu140 still plays a role in contributing to hydrogen-bond network. This behavior is most likely conserved throughout the UbiX family due to the structural similarity of the active sites of those proteins. SIGNIFICANCE Mechanistic insights into a crucial biochemical process, the biosynthesis of prFMN, are provided. This study, although purely computational, extends and perfectly complements the knowledge obtained in classical laboratory experiments.
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Affiliation(s)
- Szymon Żaczek
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Żeromskiego 116, 90-924 Lodz, Poland
| | - Agnieszka Dybala-Defratyka
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology, Żeromskiego 116, 90-924 Lodz, Poland.
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21
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Flavin-enabled reductive and oxidative epoxide ring opening reactions. Nat Commun 2022; 13:4896. [PMID: 35986005 PMCID: PMC9391479 DOI: 10.1038/s41467-022-32641-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 08/08/2022] [Indexed: 12/23/2022] Open
Abstract
Epoxide ring opening reactions are common and important in both biological processes and synthetic applications and can be catalyzed in a non-redox manner by epoxide hydrolases or reductively by oxidoreductases. Here we report that fluostatins (FSTs), a family of atypical angucyclines with a benzofluorene core, can undergo nonenzyme-catalyzed epoxide ring opening reactions in the presence of flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NADH). The 2,3-epoxide ring in FST C is shown to open reductively via a putative enol intermediate, or oxidatively via a peroxylated intermediate with molecular oxygen as the oxidant. These reactions lead to multiple products with different redox states that possess a single hydroxyl group at C-2, a 2,3-vicinal diol, a contracted five-membered A-ring, or an expanded seven-membered A-ring. Similar reactions also take place in both natural products and other organic compounds harboring an epoxide adjacent to a carbonyl group that is conjugated to an aromatic moiety. Our findings extend the repertoire of known flavin chemistry that may provide new and useful tools for organic synthesis. Epoxide ring opening reactions are important in both biological processes and synthetic applications. Here, the authors show that flavin cofactors can catalyze reductive and oxidative epoxide ring opening reactions and propose the underlying mechanisms.
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22
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Iyer A, Reis RAG, Agniswamy J, Weber IT, Gadda G. Discovery of a new flavin N5-adduct in a tyrosine to phenylalanine variant of d-Arginine dehydrogenase. Arch Biochem Biophys 2022; 715:109100. [PMID: 34864048 DOI: 10.1016/j.abb.2021.109100] [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: 10/29/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 11/02/2022]
Abstract
d-Arginine dehydrogenase from Pseudomonas aeruginosa (PaDADH) catalyzes the flavin-dependent oxidation of d-arginine and other d-amino acids. Here, we report the crystal structure at 1.29 Å resolution for PaDADH-Y249F expressed and co-crystallized with d-arginine. The overall structure of PaDADH-Y249F resembled PaDADH-WT, but the electron density for the flavin cofactor was ambiguous, suggesting the presence of modified flavins. Electron density maps and mass spectrometric analysis confirmed the presence of both N5-(4-guanidino-oxobutyl)-FAD and 6-OH-FAD in a single crystal of PaDADH-Y249F and helped with the further refinement of the X-ray crystal structure. The versatility of the reduced flavin is apparent in the PaDADH-Y249F structure and is evidenced by the multiple functions it can perform in the same active site.
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Affiliation(s)
- Archana Iyer
- Department of Chemistry, Georgia State University, Atlanta, GA, 30302, USA
| | - Renata A G Reis
- Department of Chemistry, Georgia State University, Atlanta, GA, 30302, USA
| | - Johnson Agniswamy
- Department of Biology, Georgia State University, Atlanta, GA, 30302, USA
| | - Irene T Weber
- Department of Chemistry, Georgia State University, Atlanta, GA, 30302, USA; Department of Biology, Georgia State University, Atlanta, GA, 30302, USA
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, GA, 30302, USA; Department of Biology, Georgia State University, Atlanta, GA, 30302, USA; Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30302, USA.
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23
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Cui CY, Chen Q, He Q, Chen C, Zhang RM, Feng Y, Sun J. Transferability of tigecycline resistance: Characterization of the expanding Tet(X) family. WIREs Mech Dis 2022; 14:e1538. [PMID: 35023325 DOI: 10.1002/wsbm.1538] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 01/13/2023]
Abstract
Tetracycline and its derivative tigecycline are clinical options against Gram-negative bacterial infections. The emergence of mobile Tet(X) enzymes that destruct tetracycline-type antibiotics is posing a big challenge to antibacterial therapy and food/environmental securities. Here, we present an update on a growing number of Tet(X) variants. We describe structure and action of Tet(X) enzyme, and discuss the evolutional origin. In addition, potential Tet(X) inhibitors are given. This mini-review might benefit better understanding of Tet(X)-mediated tigecycline resistance. This article is categorized under: Infectious Diseases > Genetics/Genomics/Epigenetics Infectious Diseases > Environmental Factors Infectious Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Chao-Yue Cui
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Qiwei Chen
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China.,Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Qian He
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Chong Chen
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Institutes of Agricultural Science and Technology Development, Yangzhou University, Yangzhou, Jiangsu, China
| | - Rong-Min Zhang
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
| | - Youjun Feng
- Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.,Department of Microbiology, and Department of General Intensive Care Unit of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,College of Animal Sciences, Zhejiang University, Hangzhou, Zhejiang, China
| | - Jian Sun
- National Risk Assessment Laboratory for Antimicrobial Resistance of Animal Original Bacteria, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Laboratory for Lingnan Modern Agriculture, South China Agricultural University, Guangzhou, Guangdong, China.,Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation, College of Veterinary Medicine, South China Agricultural University, Guangzhou, Guangdong, China
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24
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Dabravolski SA, Isayenkov SV. Evolution of the Cytokinin Dehydrogenase (CKX) Domain. J Mol Evol 2021; 89:665-677. [PMID: 34757471 DOI: 10.1007/s00239-021-10035-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/30/2021] [Indexed: 01/05/2023]
Abstract
Plant hormone cytokinins are important regulators of plant development, response to environmental stresses and interplay with other plant hormones. Cytokinin dehydrogenases (CKXs) are proteins responsible for the irreversible break-down of cytokinins to the adenine and aldehyde. Even though plant CKXs have been extensively studied, homologous proteins from other taxa remain mainly uncharacterised. Here we present our study on the molecular evolution and divergence of the CKX from bacteria, fungi, amoeba and viridiplantae. Although CKXs are present in eukaryotes and prokaryotes, they are missing in algae and metazoan taxa. The prevalent domain architecture consists of the FAD-binding and cytokinin binding domains, whereas some bacteria appear to have only cytokinin binding domain proteins. The CKXs play important role in the various aspects of plant life including control of plant development, response to biotic and abiotic stress, influence nutrition. Results of our study suggested that CKX originates from the FAD-linked C-terminal oxidase and has a defence-oriented function. The obtained results significantly extend the current understanding of the cytokinin dehydrogenases structure-function from the relationship to homologues from other taxa and provide a starting point baseline for their future functional characterization.
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Affiliation(s)
- Siarhei A Dabravolski
- Department of Clinical Diagnostics, Vitebsk State Academy of Veterinary Medicine [UO VGAVM], Dovatora str. 7/11, 21002, Vitebsk, Belarus
| | - Stanislav V Isayenkov
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China.
- Department of Plant Food Products and Biofortification, Institute of Food Biotechnology and Genomics, NAS of Ukraine, Osipovskogo str., 2a, Kyiv-123, Kyiv, 04123, Ukraine.
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25
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Lee YJ, Dai N, Müller SI, Guan C, Parker MJ, Fraser ME, Walsh SE, Sridar J, Mulholland A, Nayak K, Sun Z, Lin YC, Comb DG, Marks K, Gonzalez R, Dowling DP, Bandarian V, Saleh L, Corrêa IR, Weigele PR. Pathways of thymidine hypermodification. Nucleic Acids Res 2021; 50:3001-3017. [PMID: 34522950 PMCID: PMC8989533 DOI: 10.1093/nar/gkab781] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 08/25/2021] [Accepted: 09/12/2021] [Indexed: 11/15/2022] Open
Abstract
The DNAs of bacterial viruses are known to contain diverse, chemically complex modifications to thymidine that protect them from the endonuclease-based defenses of their cellular hosts, but whose biosynthetic origins are enigmatic. Up to half of thymidines in the Pseudomonas phage M6, the Salmonella phage ViI, and others, contain exotic chemical moieties synthesized through the post-replicative modification of 5-hydroxymethyluridine (5-hmdU). We have determined that these thymidine hypermodifications are derived from free amino acids enzymatically installed on 5-hmdU. These appended amino acids are further sculpted by various enzyme classes such as radical SAM isomerases, PLP-dependent decarboxylases, flavin-dependent lyases and acetyltransferases. The combinatorial permutations of thymidine hypermodification genes found in viral metagenomes from geographically widespread sources suggests an untapped reservoir of chemical diversity in DNA hypermodifications.
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Affiliation(s)
- Yan-Jiun Lee
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Nan Dai
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Stephanie I Müller
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Chudi Guan
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Mackenzie J Parker
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Morgan E Fraser
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Shannon E Walsh
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Janani Sridar
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Andrew Mulholland
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Krutika Nayak
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Zhiyi Sun
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Yu-Cheng Lin
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Donald G Comb
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Katherine Marks
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Reyaz Gonzalez
- Chemistry Department, University of Massachusetts Boston, 100 William T. Morrissey Blvd. Boston, MA02125, USA
| | - Daniel P Dowling
- Chemistry Department, University of Massachusetts Boston, 100 William T. Morrissey Blvd. Boston, MA02125, USA
| | - Vahe Bandarian
- Department of Chemistry, University of Utah, 315 South 1400 East Salt Lake City, UT 84112, USA
| | - Lana Saleh
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Ivan R Corrêa
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
| | - Peter R Weigele
- Research Department, New England Biolabs, Inc., 240 County Road, Ipswich, MA01938, USA
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26
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Datar PM, Marsh ENG. Decarboxylation of Aromatic Carboxylic Acids by the Prenylated-FMN-dependent Enzyme Phenazine-1-carboxylic Acid Decarboxylase. ACS Catal 2021. [DOI: 10.1021/acscatal.1c03040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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27
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Beagan DM, Maciulis NA, Pink M, Carta V, Huerfano IJ, Chen CH, Caulton KG. A Redox-Active Tetrazine-Based Pincer Ligand for the Reduction of N-Oxyanions Using a Redox-Inert Metal. Chemistry 2021; 27:11676-11681. [PMID: 34008888 DOI: 10.1002/chem.202101302] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Indexed: 01/01/2023]
Abstract
The reaction chemistry of the bis-tetrazinyl pyridine ligand (btzp) towards nitrogen oxyanions coordinated to zinc is studied in order to explore the reduction of the NOx - substrates with a redox-active ligand in the absence of redox activity at the metal. Following syntheses and characterization of (btzp)ZnX2 for X=Cl, NO3 and NO2 , featuring O-Zn linkage of both nitrogen oxyanions, it is shown that a silylating agent selectively delivers silyl substituents to tetrazine nitrogens, without reductive deoxygenation of NOx -1 . A new synthesis of the highly hydrogenated H4 btzp, containing two dihydrotetrazine reductants is described as is the synthesis and characterization of (H4 btzp)ZnX2 for X=Cl and NO3 , both of which show considerable hydrogen bonding potential of the dihydrotetrazine ring NH groups. The (H4 btzp)ZnCl2 complex does not bind zinc in the pincer pocket, but instead H4 btzp becomes a bridge between neighboring atoms through tetrazine nitrogen atoms, forming a polymeric chain. The reaction of AgNO2 with (H4 btzp)ZnCl2 is shown to proceed with fast nitrite deoxygenation, yielding water and free NO. Half of the H4 btzp reducing equivalents form Ag0 and thus the chloride ligand remains coordinated to the zinc metal center to yield (btzp)ZnCl2 . To compare with AgNO2 , experiments of (H4 btzp)ZnCl2 with NaNO2 result in salt metathesis between chloride and nitrite, highlighting the importance of a redox-active cation in the reduction of nitrite to NO.
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Affiliation(s)
- Daniel M Beagan
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
| | - Nicholas A Maciulis
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
| | - Maren Pink
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
| | - Veronica Carta
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
| | - I J Huerfano
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
| | - Chun-Hsing Chen
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
| | - Kenneth G Caulton
- Department of Chemistry, Indiana University, 47405, Bloomington, Indiana, USA
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28
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Ma GL, Tran HT, Low ZJ, Candra H, Pang LM, Cheang QW, Fang M, Liang ZX. Pathway Retrofitting Yields Insights into the Biosynthesis of Anthraquinone-Fused Enediynes. J Am Chem Soc 2021; 143:11500-11509. [PMID: 34293863 DOI: 10.1021/jacs.1c03911] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Anthraquinone-fused enediynes (AQEs) are renowned for their distinctive molecular architecture, reactive enediyne warhead, and potent anticancer activity. Although the first members of AQEs, i.e., dynemicins, were discovered three decades ago, how their nitrogen-containing carbon skeleton is synthesized by microbial producers remains largely a mystery. In this study, we showed that the recently discovered sungeidine pathway is a "degenerative" AQE pathway that contains upstream enzymes for AQE biosynthesis. Retrofitting the sungeidine pathway with genes from the dynemicin pathway not only restored the biosynthesis of the AQE skeleton but also produced a series of novel compounds likely as the cycloaromatized derivatives of chemically unstable biosynthetic intermediates. The results suggest a cascade of highly surprising biosynthetic steps leading to the formation of the anthraquinone moiety, the hallmark C8-C9 linkage via alkyl-aryl cross-coupling, and the characteristic epoxide functionality. The findings provide unprecedented insights into the biosynthesis of AQEs and pave the way for examining these intriguing biosynthetic enzymes.
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Affiliation(s)
- Guang-Lei Ma
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Hoa Thi Tran
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Zhen Jie Low
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Hartono Candra
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Li Mei Pang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Qing Wei Cheang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
| | - Mingliang Fang
- School of Civil and Environmental Engineering, Nanyang Technological University, Singapore 639798
| | - Zhao-Xun Liang
- School of Biological Sciences, Nanyang Technological University, Singapore 637551
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29
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Song Y, Wang X, Wang L, Dong Z, Fan S, Huang P, Zeng J, Cheng P. Visible-light promoted allylation of N-substituted tetrahydroisoquinoline using riboflavin tetra-acetate as photocatalyst. Tetrahedron Lett 2021. [DOI: 10.1016/j.tetlet.2021.153286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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30
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Bou-Nader C, Stull FW, Pecqueur L, Simon P, Guérineau V, Royant A, Fontecave M, Lombard M, Palfey BA, Hamdane D. An enzymatic activation of formaldehyde for nucleotide methylation. Nat Commun 2021; 12:4542. [PMID: 34315871 PMCID: PMC8316439 DOI: 10.1038/s41467-021-24756-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 07/05/2021] [Indexed: 11/09/2022] Open
Abstract
Folate enzyme cofactors and their derivatives have the unique ability to provide a single carbon unit at different oxidation levels for the de novo synthesis of amino-acids, purines, or thymidylate, an essential DNA nucleotide. How these cofactors mediate methylene transfer is not fully settled yet, particularly with regard to how the methylene is transferred to the methylene acceptor. Here, we uncovered that the bacterial thymidylate synthase ThyX, which relies on both folate and flavin for activity, can also use a formaldehyde-shunt to directly synthesize thymidylate. Combining biochemical, spectroscopic and anaerobic crystallographic analyses, we showed that formaldehyde reacts with the reduced flavin coenzyme to form a carbinolamine intermediate used by ThyX for dUMP methylation. The crystallographic structure of this intermediate reveals how ThyX activates formaldehyde and uses it, with the assistance of active site residues, to methylate dUMP. Our results reveal that carbinolamine species promote methylene transfer and suggest that the use of a CH2O-shunt may be relevant in several other important folate-dependent reactions.
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Affiliation(s)
- Charles Bou-Nader
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France.,Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, 20892, USA
| | - Frederick W Stull
- Programs in Chemical Biology and the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ludovic Pecqueur
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France
| | - Philippe Simon
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France
| | - Vincent Guérineau
- CNRS, Institut de Chimie des Substances Naturelles UPR 2301, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Antoine Royant
- CEA, CNRS, Institut de Biologie Structurale (IBS), Université Grenoble Alpes, Grenoble, France.,European Synchrotron Radiation Facility, Grenoble, France
| | - Marc Fontecave
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France
| | - Murielle Lombard
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France
| | - Bruce A Palfey
- Programs in Chemical Biology and the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Djemel Hamdane
- Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, Université Pierre et Marie Curie, Paris, France.
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31
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Bell JD, Murphy JA. Recent advances in visible light-activated radical coupling reactions triggered by (i) ruthenium, (ii) iridium and (iii) organic photoredox agents. Chem Soc Rev 2021; 50:9540-9685. [PMID: 34309610 DOI: 10.1039/d1cs00311a] [Citation(s) in RCA: 134] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Photoredox chemistry with organic or transition metal agents has been reviewed in earlier years, but such is the pace of progress that we will overlap very little with earlier comprehensive reviews. This review first presents an overview of the area of research and then examines recent examples of C-C, C-N, C-O and C-S bond formations via radical intermediates with transition metal and organic radical promoters. Recent successes with Birch reductions are also included. The transition metal chemistry will be restricted to photocatalysts based on the most widely used metals, Ru and Ir, but includes coupling chemistries that take advantage of low-valent nickel, or occasionally copper, complexes to process the radicals that are formed. Our focus is on developments in the past 10 years (2011-2021). This period has also seen great advances in the chemistry of organic photoredox reagents and the review covers this area. The review is intended to present highlights and is not comprehensive.
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Affiliation(s)
- Jonathan D Bell
- Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, UK.
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32
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Stricker F, Kölsch JC, Beil SB, Preiß S, Waldvogel SR, Opatz T, Besenius P. Facile access to foldable redox-active flavin-peptide conjugates. Org Biomol Chem 2021; 19:4483-4486. [PMID: 33960997 DOI: 10.1039/d1ob00414j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A convenient approach for the synthesis of foldable redox-active flavin peptide conjugates was established. A model β-hairpin oligopeptide motif was utilized to demonstrate that azidolysine side-chains are readily functionalised with an alkyne-bearing flavine derivative. The folding equilibrium of the peptide backbone as well as the redox behaviour of the flavin moieties remains intact after the conjugation.
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Affiliation(s)
- Friedrich Stricker
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Jonas Christopher Kölsch
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Sebastian B Beil
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany. and Graduate School of Materials Science in Mainz, Staudingerweg 9, 55128 Mainz, Germany
| | - Sebastian Preiß
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Siegfried R Waldvogel
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany. and Graduate School of Materials Science in Mainz, Staudingerweg 9, 55128 Mainz, Germany
| | - Till Opatz
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Pol Besenius
- Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany. and Graduate School of Materials Science in Mainz, Staudingerweg 9, 55128 Mainz, Germany
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33
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Wörner J, Chen J, Bacher A, Weber S. Non-classical disproportionation revealed by photo-chemically induced dynamic nuclear polarization NMR. MAGNETIC RESONANCE (GOTTINGEN, GERMANY) 2021; 2:281-290. [PMID: 37904753 PMCID: PMC10539781 DOI: 10.5194/mr-2-281-2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Accepted: 04/07/2021] [Indexed: 11/01/2023]
Abstract
Photo-chemically induced dynamic nuclear polarization (photo-CIDNP) was used to observe the light-induced disproportionation reaction of 6,7,8-trimethyllumazine starting out from its triplet state to generate a pair of radicals comprising a one-electron reduced and a one-electron oxidized species. Our evidence is based on the measurement of two marker proton hyperfine couplings, A iso (H(6α )) and A iso (H(8α )), which we correlated to predictions from density functional theory. The ratio of these two hyperfine couplings is reversed in the oxidized and the reduced radical species. Observation of the dismutation reaction is facilitated by the exceptional C-H acidity of the methyl group at position 7 of 6,7,8-trimethyllumazine and the slow proton exchange associated with it, which leads to NMR-distinguishable anionic (TML- ) and neutral (TMLH) protonation forms.
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Affiliation(s)
- Jakob Wörner
- Institute of Physical Chemistry, Albert-Ludwigs-Universität
Freiburg, Freiburg, 79104, Germany
| | - Jing Chen
- Institute of Physical Chemistry, Albert-Ludwigs-Universität
Freiburg, Freiburg, 79104, Germany
| | - Adelbert Bacher
- Department of Chemistry, Technical University of Munich, Garching,
85748, Germany
| | - Stefan Weber
- Institute of Physical Chemistry, Albert-Ludwigs-Universität
Freiburg, Freiburg, 79104, Germany
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34
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Vanoni MA. Iron-sulfur flavoenzymes: the added value of making the most ancient redox cofactors and the versatile flavins work together. Open Biol 2021; 11:210010. [PMID: 33947244 PMCID: PMC8097209 DOI: 10.1098/rsob.210010] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Iron-sulfur (Fe-S) flavoproteins form a broad and growing class of complex, multi-domain and often multi-subunit proteins coupling the most ancient cofactors (the Fe-S clusters) and the most versatile coenzymes (the flavin coenzymes, FMN and FAD). These enzymes catalyse oxidoreduction reactions usually acting as switches between donors of electron pairs and acceptors of single electrons, and vice versa. Through selected examples, the enzymes' structure−function relationships with respect to rate and directionality of the electron transfer steps, the role of the apoprotein and its dynamics in modulating the electron transfer process will be discussed.
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Affiliation(s)
- Maria Antonietta Vanoni
- Dipartimento di Bioscienze, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
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35
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Iyer A, Reis RAG, Gannavaram S, Momin M, Spring-Connell AM, Orozco-Gonzalez Y, Agniswamy J, Hamelberg D, Weber IT, Gozem S, Wang S, Germann MW, Gadda G. A Single-Point Mutation in d-Arginine Dehydrogenase Unlocks a Transient Conformational State Resulting in Altered Cofactor Reactivity. Biochemistry 2021; 60:711-724. [PMID: 33630571 DOI: 10.1021/acs.biochem.1c00054] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Proteins are inherently dynamic, and proper enzyme function relies on conformational flexibility. In this study, we demonstrated how an active site residue changes an enzyme's reactivity by modulating fluctuations between conformational states. Replacement of tyrosine 249 (Y249) with phenylalanine in the active site of the flavin-dependent d-arginine dehydrogenase yielded an enzyme with both an active yellow FAD (Y249F-y) and an inactive chemically modified green FAD, identified as 6-OH-FAD (Y249F-g) through various spectroscopic techniques. Structural investigation of Y249F-g and Y249F-y variants by comparison to the wild-type enzyme showed no differences in the overall protein structure and fold. A closer observation of the active site of the Y249F-y enzyme revealed an alternative conformation for some active site residues and the flavin cofactor. Molecular dynamics simulations probed the alternate conformations observed in the Y249F-y enzyme structure and showed that the enzyme variant with FAD samples a metastable conformational state, not available to the wild-type enzyme. Hybrid quantum/molecular mechanical calculations identified differences in flavin electronics between the wild type and the alternate conformation of the Y249F-y enzyme. The computational studies further indicated that the alternate conformation in the Y249F-y enzyme is responsible for the higher spin density at the C6 atom of flavin, which is consistent with the formation of 6-OH-FAD in the variant enzyme. The observations in this study are consistent with an alternate conformational space that results in fine-tuning the microenvironment around a versatile cofactor playing a critical role in enzyme function.
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Affiliation(s)
- Archana Iyer
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Renata A G Reis
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Swathi Gannavaram
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Mohamed Momin
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | | | | | - Johnson Agniswamy
- Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States
| | - Donald Hamelberg
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Irene T Weber
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States
| | - Samer Gozem
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Siming Wang
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States
| | - Markus W Germann
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States
| | - Giovanni Gadda
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Department of Biology, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
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36
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Paul CE, Eggerichs D, Westphal AH, Tischler D, van Berkel WJH. Flavoprotein monooxygenases: Versatile biocatalysts. Biotechnol Adv 2021; 51:107712. [PMID: 33588053 DOI: 10.1016/j.biotechadv.2021.107712] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 01/27/2021] [Accepted: 02/06/2021] [Indexed: 12/13/2022]
Abstract
Flavoprotein monooxygenases (FPMOs) are single- or two-component enzymes that catalyze a diverse set of chemo-, regio- and enantioselective oxyfunctionalization reactions. In this review, we describe how FPMOs have evolved from model enzymes in mechanistic flavoprotein research to biotechnologically relevant catalysts that can be applied for the sustainable production of valuable chemicals. After a historical account of the development of the FPMO field, we explain the FPMO classification system, which is primarily based on protein structural properties and electron donor specificities. We then summarize the most appealing reactions catalyzed by each group with a focus on the different types of oxygenation chemistries. Wherever relevant, we report engineering strategies that have been used to improve the robustness and applicability of FPMOs.
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Affiliation(s)
- Caroline E Paul
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Daniel Eggerichs
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Adrie H Westphal
- Laboratory of Biochemistry, Wageningen University, Stippeneng 4, 6708 WE Wageningen, The Netherlands
| | - Dirk Tischler
- Microbial Biotechnology, Faculty of Biology and Biotechnology, Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
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37
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Reis RAG, Li H, Johnson M, Sobrado P. New frontiers in flavin-dependent monooxygenases. Arch Biochem Biophys 2021; 699:108765. [PMID: 33460580 DOI: 10.1016/j.abb.2021.108765] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 12/15/2022]
Abstract
Flavin-dependent monooxygenases catalyze a wide variety of redox reactions in important biological processes and are responsible for the synthesis of highly complex natural products. Although much has been learned about FMO chemistry in the last ~80 years of research, several aspects of the reactions catalyzed by these enzymes remain unknown. In this review, we summarize recent advancements in the flavin-dependent monooxygenase field including aspects of flavin dynamics, formation and stabilization of reactive species, and the hydroxylation mechanism. Novel catalysis of flavin-dependent N-oxidases involving consecutive oxidations of amines to generate oximes or nitrones is presented and the biological relevance of the products is discussed. In addition, the activity of some FMOs have been shown to be essential for the virulence of several human pathogens. We also discuss the biomedical relevance of FMOs in antibiotic resistance and the efforts to identify inhibitors against some members of this important and growing family enzymes.
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Affiliation(s)
| | - Hao Li
- Department of Biochemistry, Blacksburg, VA, 24061, USA
| | - Maxim Johnson
- Department of Biochemistry, Blacksburg, VA, 24061, USA
| | - Pablo Sobrado
- Department of Biochemistry, Blacksburg, VA, 24061, USA; Center for Drug Discovery, Virginia Tech, Blacksburg, VA, 24061, USA.
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Toplak M, Matthews A, Teufel R. The devil is in the details: The chemical basis and mechanistic versatility of flavoprotein monooxygenases. Arch Biochem Biophys 2020; 698:108732. [PMID: 33358998 DOI: 10.1016/j.abb.2020.108732] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/15/2020] [Accepted: 12/19/2020] [Indexed: 02/07/2023]
Abstract
The ubiquitous flavoenzymes commonly catalyze redox chemistry such as the monooxygenation of organic substrates and are both widely utilized in nature (e.g., in primary and secondary metabolism) and of significant industrial interest. In this work, we highlight the structural and mechanistic characteristics of the distinct types of flavoprotein monooxygenases (FPMOs). We thereby illustrate the chemical basis of FPMO catalysis, which enables reactions such as (aromatic) hydroxylation, epoxidation, (de)halogenation, heteroatom oxygenation, Baeyer-Villiger oxidation, α-hydroxylation of ketones, or non-oxidative carbon-hetero bond cleavage. This seemingly unmatched versatility in oxygenation chemistry results from extensive fine-tuning and regiospecific functionalization of the flavin cofactor that is tightly controlled by the surrounding protein matrix. Accordingly, FPMOs steer the formation of covalent flavin-oxygen adducts for oxygen transfer in the form of the classical flavin-C4a-(hydro)peroxide or the recently discovered N5-functionalized flavins (i.e. the flavin-N5-oxide and the flavin-N5-peroxide), while in rare cases covalent oxygen adduct formation may be foregone entirely. Finally, we speculate about hitherto undiscovered flavin-mediated oxygenation reactions and compare FPMOs to cytochrome P450 monooxygenases, before addressing open questions and challenges for the future investigation of FPMOs.
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Affiliation(s)
- Marina Toplak
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Arne Matthews
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany
| | - Robin Teufel
- Faculty of Biology, University of Freiburg, 79104, Freiburg, Germany.
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Kaneshiro AK, Koebke KJ, Zhao C, Ferguson KL, Ballou DP, Palfey BA, Ruotolo BT, Marsh ENG. Kinetic Analysis of Transient Intermediates in the Mechanism of Prenyl-Flavin-Dependent Ferulic Acid Decarboxylase. Biochemistry 2020; 60:125-134. [PMID: 33342208 DOI: 10.1021/acs.biochem.0c00856] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ferulic acid decarboxylase catalyzes the decarboxylation of various substituted phenylacrylic acids to their corresponding styrene derivatives and CO2 using the recently discovered cofactor prenylated FMN (prFMN). The mechanism involves an unusual 1,3-dipolar cycloaddition reaction between prFMN and the substrate to generate a cycloadduct capable of undergoing decarboxylation. Using native mass spectrometry, we show the enzyme forms a stable prFMN-styrene cycloadduct that accumulates on the enzyme during turnover. Pre-steady state kinetic analysis of the reaction using ultraviolet-visible stopped-flow spectroscopy reveals a complex pattern of kinetic behavior, best described by a half-of-sites model involving negative cooperativity between the two subunits of the dimeric enzyme. For the reactive site, the cycloadduct of prFMN with phenylacylic acid is formed with a kapp of 131 s-1. This intermediate converts to the prFMN-styrene cycloadduct with a kapp of 75 s-1. Cycloelimination of the prFMN-styrene cycloadduct to generate styrene and free enzyme appears to determine kcat for the overall reaction, which is 11.3 s-1.
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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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Conformation of the Intermediates in the Reaction Catalyzed by Protoporphyrinogen Oxidase: An In Silico Analysis. Int J Mol Sci 2020; 21:ijms21249495. [PMID: 33327448 PMCID: PMC7764921 DOI: 10.3390/ijms21249495] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/09/2020] [Accepted: 12/10/2020] [Indexed: 12/29/2022] Open
Abstract
Protoporphyrinogen oxidase (PPO) is a critical enzyme across life as the last common step in the synthesis of many metalloporphyrins. The reaction mechanism of PPO was assessed in silico and the unstructured loop near the binding pocket was investigated. The substrate, intermediates, and product were docked in the catalytic domain of PPO using a modified Autodock method, introducing flexibility in the macrocycles. Sixteen PPO protein sequences across phyla were aligned and analyzed with Phyre2 and ProteinPredict to study the unstructured loop from residue 204–210 in the H. sapiens structure. Docking of the substrate, intermediates, and product all resulted in negative binding energies, though the substrate had a lower energy than the others by 40%. The α-H of C10 was found to be 1.4 angstroms closer to FAD than the β-H, explaining previous reports of the reaction occurring on the meso face of the substrate. A lack of homology in sequence or length in the unstructured loop indicates a lack of function for the protein reaction. This docking study supports a reaction mechanism proposed previously whereby all hydride abstractions occur on the C10 of the tetrapyrrole followed by tautomeric rearrangement to prepare the intermediate for the next reaction.
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Beaupre BA, Moran GR. N5 Is the New C4a: Biochemical Functionalization of Reduced Flavins at the N5 Position. Front Mol Biosci 2020; 7:598912. [PMID: 33195440 PMCID: PMC7662398 DOI: 10.3389/fmolb.2020.598912] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/05/2020] [Indexed: 12/31/2022] Open
Abstract
For three decades the C4a-position of reduced flavins was the known site for covalency within flavoenzymes. The reactivity of this position of the reduced isoalloxazine ring with the dioxygen ground-state triplet established the C4a as a site capable of one-electron chemistry. Within the last two decades new types of reduced flavin reactivity have been documented. These studies reveal that the N5 position is also a protean site of reactivity, that is capable of nucleophilic attack to form covalent bonds with substrates. In addition, though the precise mechanism of dioxygen reactivity is yet to be definitively demonstrated, it is clear that the N5 position is directly involved in substrate oxygenation in some enzymes. In this review we document the lineage of discoveries that identified five unique modes of N5 reactivity that collectively illustrate the versatility of this position of the reduced isoalloxazine ring.
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Affiliation(s)
- Brett A Beaupre
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States
| | - Graham R Moran
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States
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Balaikaite A, Chisanga M, Fisher K, Heyes DJ, Spiess R, Leys D. Ferulic Acid Decarboxylase Controls Oxidative Maturation of the Prenylated Flavin Mononucleotide Cofactor. ACS Chem Biol 2020; 15:2466-2475. [PMID: 32840348 DOI: 10.1021/acschembio.0c00456] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prenylated flavin mononucleotide (prFMN) is a recently discovered modified flavin cofactor containing an additional nonaromatic ring, connected to the N5 and C6 atoms. This cofactor underpins reversible decarboxylation catalyzed by members of the widespread UbiD enzyme family and is produced by the flavin prenyltransferase UbiX. Oxidative maturation of the UbiX product prFMNH2 to the corresponding oxidized prFMNiminium is required for ferulic acid decarboxylase (Fdc1; a UbiD-type enzyme) activity. However, it is unclear what role the Fdc1 enzyme plays in this process. Here, we demonstrate that, in the absence of Fdc1, prFMNH2 oxidation by O2 proceeds via a transient semiquinone prFMNradical species and culminates in a remarkably stable prFMN-hydroperoxide species. Neither forms of prFMN are able to support Fdc1 activity. Instead, enzyme activation using O2-mediated oxidation requires prFMNH2 binding prior to oxygen exposure, confirming that UbiD enzymes play a role in O2-mediated oxidative maturation. In marked contrast, alternative oxidants such as potassium ferricyanide support prFMNiminium formation both in solution and in Fdc1.
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Affiliation(s)
- Arune Balaikaite
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Malama Chisanga
- Department of Biochemistry, Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
- Department of Chemistry, School of Mathematics and Natural Sciences, Copperbelt University, Kitwe, Zambia
| | - Karl Fisher
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Derren J. Heyes
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - Reynard Spiess
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
| | - David Leys
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester M1 7DN, United Kingdom
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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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Tolomeo M, Nisco A, Leone P, Barile M. Development of Novel Experimental Models to Study Flavoproteome Alterations in Human Neuromuscular Diseases: The Effect of Rf Therapy. Int J Mol Sci 2020; 21:ijms21155310. [PMID: 32722651 PMCID: PMC7432027 DOI: 10.3390/ijms21155310] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 02/07/2023] Open
Abstract
Inborn errors of Riboflavin (Rf) transport and metabolism have been recently related to severe human neuromuscular disorders, as resulting in profound alteration of human flavoproteome and, therefore, of cellular bioenergetics. This explains why the interest in studying the “flavin world”, a topic which has not been intensively investigated before, has increased much over the last few years. This also prompts basic questions concerning how Rf transporters and FAD (flavin adenine dinucleotide) -forming enzymes work in humans, and how they can create a coordinated network ensuring the maintenance of intracellular flavoproteome. The concept of a coordinated cellular “flavin network”, introduced long ago studying humans suffering for Multiple Acyl-CoA Dehydrogenase Deficiency (MADD), has been, later on, addressed in model organisms and more recently in cell models. In the frame of the underlying relevance of a correct supply of Rf in humans and of a better understanding of the molecular rationale of Rf therapy in patients, this review wants to deal with theories and existing experimental models in the aim to potentiate possible therapeutic interventions in Rf-related neuromuscular diseases.
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Abstract
Flavoenzymes are broadly employed as biocatalysts for a large variety of reactions, owing to the chemical versatility of the flavin cofactor. Oxidases set aside, many flavoenzymes require a source of electrons in form of the biological reductant nicotinamide NAD(P)H in order to initiate catalysis via the reduced flavin. Chemists can take advantage of the reactivity of reduced flavins with oxygen to carry out monooxygenation reactions, while the reduced flavin can also be used for formal hydrogenation reactions. The main advantage of these reactions compared to chemical approaches is the frequent regio-, chemo- and stereo-selectivity of the biocatalysts, which allows the synthesis of chiral molecules in optically active form. This chapter provides an overview of the variety of biocatalytic processes that have been developed with flavoenzymes, with a particular focus on nicotinamide-dependent enzymes. The diversity of molecules obtained is highlighted and in several cases, strategies that allow control of the stereochemical outcome of the reactions are reviewed.
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Affiliation(s)
- Mélanie Hall
- Department of Chemistry, University of Graz, Graz, Austria.
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47
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Thermal, electrochemical and photochemical reactions involving catalytically versatile ene reductase enzymes. Enzymes 2020; 47:491-515. [PMID: 32951833 DOI: 10.1016/bs.enz.2020.05.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Successful exploitation of biocatalytic processes employing flavoproteins requires the implementation of cost-effective solutions to circumvent the need to supply costly nicotinamide coenzymes as reducing equivalents. Chemical syntheses harnessing the power of the flavoprotein ene reductases will likely increase the range and/or optical purity of available fine chemicals and pharmaceuticals due to their ability to catalyze asymmetric bioreductions. This review will outline current progress in the design of alternative routes to ene reductase flavin activation, most notably within the Old Yellow Enzyme family. A variety of chemical, enzymatic, electrochemical and photocatalytic routes have been employed, designed to eliminate the need for nicotinamide coenzymes or provide cost-effective alternatives to efficient recycling. Photochemical approaches have also enabled novel mechanistic routes of ene reductases to become available, opening up the possibility of accessing a wider range of non-natural chemical diversity.
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48
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Abstract
The reversible (de)carboxylation of unsaturated carboxylic acids is carried out by the UbiX-UbiD system, ubiquitously present in microbes. The biochemical basis of this challenging reaction has recently been uncovered by the discovery of the UbiD cofactor, prenylated FMN (prFMN). This heavily modified flavin is synthesized by the flavin prenyltransferase UbiX, which catalyzes the non-metal dependent prenyl transfer from dimethylallyl(pyro)phosphate (DMAP(P)) to the flavin N5 and C6 positions, creating a fourth non-aromatic ring. Following prenylation, prFMN undergoes oxidative maturation to form the iminium species required for UbiD activity. prFMNiminium acts as a prostethic group and is bound via metal ion mediated interactions between UbiD and the prFMNiminium phosphate moiety. The modified isoalloxazine ring is place adjacent to the E(D)-R-E UbiD signature sequent motif. The fungal ferulic acid decarboxylase Fdc from Aspergillus niger has emerged as a UbiD-model system, and has yielded atomic level insight into the prFMNiminium mediated (de)carboxylation. A wealth of data now supports a mechanism reliant on reversible 1,3 dipolar cycloaddition between substrate and cofactor for this enzyme. This poses the intriguing question whether a similar mechanism is used by all UbiD enzymes, especially those that act as carboxylases on inherently more difficult substrates such as phenylphosphate or benzene/naphthalene. Indeed, considerable variability in terms of oligomerization, domain motion and active site structure is now reported for the UbiD family.
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Affiliation(s)
- Annica Saaret
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom
| | - Arune Balaikaite
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom
| | - David Leys
- Manchester Institute of Biotechnology, School of Chemistry, University of Manchester, Manchester, United Kingdom.
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Mordhorst S, Andexer JN. Round, round we go - strategies for enzymatic cofactor regeneration. Nat Prod Rep 2020; 37:1316-1333. [PMID: 32582886 DOI: 10.1039/d0np00004c] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Covering: up to the beginning of 2020Enzymes depending on cofactors are essential in many biosynthetic pathways of natural products. They are often involved in key steps: catalytic conversions that are difficult to achieve purely with synthetic organic chemistry. Hence, cofactor-dependent enzymes have great potential for biocatalysis, on the condition that a corresponding cofactor regeneration system is available. For some cofactors, these regeneration systems require multiple steps; such complex enzyme cascades/multi-enzyme systems are (still) challenging for in vitro biocatalysis. Further, artificial cofactor analogues have been synthesised that are more stable, show an altered reaction range, or act as inhibitors. The development of bio-orthogonal systems that can be used for the production of modified natural products in vivo is an ongoing challenge. In light of the recent progress in this field, this review aims to provide an overview of general strategies involving enzyme cofactors, cofactor analogues, and regeneration systems; highlighting the current possibilities for application of enzymes using some of the most common cofactors.
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Affiliation(s)
- Silja Mordhorst
- Institute of Microbiology, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
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Etz BD, DuClos JM, Vyas S. Investigating the Photochemistry of C7 and C8 Functionalized N(5)-Ethyl-flavinium Cation: A Computational Study. J Phys Chem A 2020; 124:4193-4201. [PMID: 32337990 DOI: 10.1021/acs.jpca.0c01938] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Flavins are a diverse set of compounds with a wide variety of biological and nonbiological applications. Applications of flavins receiving attention recently consist of electro- and photocatalytic oxidation of substrates for organic synthesis, bioengineered nanotechnology, and water splitting catalysts, among others. While there is vast knowledge regarding the structure-property relationships of flavins and their electrochemistry, there is much less work elucidating the structure property relationships as they pertain to flavinium photochemistry. Herein, we report the effect of molecular tailoring on the molecular properties of N(5)-ethyl-flavinium cation (Et-Fl+), a derivative of the biocatalytic coenzyme riboflavin, by incorporating electron withdrawing and donating groups at the C7 and C8 position of the isoalloxazine ring. The presence of electron withdrawing groups at the C8 position caused a red shift in the absorption spectrum, while the electron donating groups caused a blue shift. Functionalization at the C7 position had the opposite effect on the absorption spectrum. The effects of single substitution were relatively negated with simultaneous functionalization at both the C8 and C7 positions. Difference density plots indicate no change in the nature of the S1 excited state, which was confirmed by optimization of the excited state geometries. The results presented in this study indicate that functionalization of the isoalloxazine unit affects the photophysical properties of N(5)-ethyl-flavinium cations.
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Affiliation(s)
- Brian D Etz
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Julie M DuClos
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
| | - Shubham Vyas
- Department of Chemistry, Colorado School of Mines, Golden, Colorado 80401, United States
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