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Siedentop R, Dziennus M, Lütz S, Rosenthal K. Debottlenecking of an In Vitro Enzyme Cascade Using a Combined Model‐ and Experiment‐Based Approach. CHEM-ING-TECH 2023. [DOI: 10.1002/cite.202200170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Affiliation(s)
- Regine Siedentop
- TU Dortmund University Chair for Bioprocess Engineering, Department of Biochemical and Chemical Engineering Emil-Figge-Straße 66 44227 Dortmund Germany
| | - Marlon Dziennus
- TU Dortmund University Chair for Bioprocess Engineering, Department of Biochemical and Chemical Engineering Emil-Figge-Straße 66 44227 Dortmund Germany
| | - Stephan Lütz
- TU Dortmund University Chair for Bioprocess Engineering, Department of Biochemical and Chemical Engineering Emil-Figge-Straße 66 44227 Dortmund Germany
| | - Katrin Rosenthal
- Constructor University Department of Life Sciences and Chemistry Campus Ring 1 28759 Bremen Germany
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2
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Valentino H, Sobrado P. Performing anaerobic stopped-flow spectrophotometry inside of an anaerobic chamber. Methods Enzymol 2019; 620:51-88. [PMID: 31072501 DOI: 10.1016/bs.mie.2019.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The catalytic cycle of most flavin-dependent enzymes can be divided into oxidative and reductive half-reactions. Although some enzymes are oxidized by electron carrier proteins or organic compounds, many use oxygen as the final electron acceptor. In order to properly study the reductive half-reaction of flavin-dependent enzyme that react with oxygen, as in the case of oxidases and monooxygenases, it is necessary to establish anaerobic conditions that will only allow the reduction process to be monitored. The reduced flavoenzyme can be further studied by exposing it to oxygen to monitor the oxidative half-reaction. Anaerobic chambers provide an ideal environment for performing these experiments as they reliably maintain an anaerobic atmosphere inside a large workspace. A common tool used to study flavin-dependent enzymes is the stopped-flow spectrophotometry. This chapter describes methods for performing stopped-flow experiments in an anaerobic chamber. We include information about the chamber components, setting up a stopped-flow spectrophotometer inside of a chamber, preparing anaerobic solutions, and performing experiments to measure the reductive and oxidative half-reactions of flavin-dependent monooxygenases.
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Affiliation(s)
- Hannah Valentino
- Department of Biochemistry, Center for Drug Discovery, Virginia Tech, Blacksburg, VA, United States
| | - Pablo Sobrado
- Department of Biochemistry, Center for Drug Discovery, Virginia Tech, Blacksburg, VA, United States.
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Neti SS, Pan JJ, Poulter CD. Mechanistic Studies of the Protonation-Deprotonation Reactions for Type 1 and Type 2 Isopentenyl Diphosphate:Dimethylallyl Diphosphate Isomerase. J Am Chem Soc 2018; 140:12900-12908. [PMID: 30183274 DOI: 10.1021/jacs.8b07274] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Type 1 and type 2 isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-1 and IDI-2) catalyze the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the fundamental building blocks for biosynthesis of isoprenoid compounds. Previous studies indicate that both isoforms of IDI catalyze isomerization by a protonation-deprotonation mechanism. IDI-1 and IDI-2 are "sluggish" enzymes with turnover times of ∼10 s-1 and ∼1 s-1, respectively. We measured incorporation of deuterium into IPP and DMAPP in D2O buffer for IDI-1 and IDI-2 under conditions where newly synthesized DMAPP is immediately and irreversibly removed by coupling its release to condensation with l-tryptophan catalyzed by dimethylallyltrytophan synthase. During the course of the reactions, we detected formation of d1, d2, and d3 isotopologues of IPP and DMAPP, which were formed during up to five isomerizations between IPP and DMAPP during each turnover. The patterns for deuterium incorporation into IPP show that d2-IPP is formed in preference to d1-IPP for both enzymes. Analysis of the patterns of deuterium incorporation are consistent with a mechanism involving addition and removal of protons by a concerted asynchronous process, where addition substantially precedes removal, or a stepwise process through a short-lived (<3 ps) tertiary carbocationic intermediate. Previous work with mechanism-based inhibitors and related model studies supports a concerted asynchronous mechanism for the enzyme-catalyzed isomerizations.
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Affiliation(s)
- Syam Sundar Neti
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112 , United States
| | - Jian-Jung Pan
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112 , United States
| | - C Dale Poulter
- Department of Chemistry , University of Utah , 315 South 1400 East , Salt Lake City , Utah 84112 , United States
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Schwarz PN, Roller L, Kulik A, Wohlleben W, Stegmann E. Engineering metabolic pathways in Amycolatopsis japonicum for the optimization of the precursor supply for heterologous brasilicardin congeners production. Synth Syst Biotechnol 2018; 3:56-63. [PMID: 29911199 PMCID: PMC5884276 DOI: 10.1016/j.synbio.2017.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/06/2017] [Accepted: 12/22/2017] [Indexed: 02/08/2023] Open
Abstract
The isoprenoid brasilicardin A is a promising immunosuppressant compound with a unique mode of action, high potency and reduced toxicity compared to today's standard drugs. However, production of brasilicardin has been hampered since the producer strain Nocardia terpenica IFM0406 synthesizes brasilicardin in only low amounts and is a biosafety level 2 organism. Previously, we were able to heterologously express the brasilicardin gene cluster in the nocardioform actinomycete Amycolatopsis japonicum. Four brasilicardin congeners, intermediates of the BraA biosynthesis, were produced. Since chemical synthesis of the brasilicardin core structure has remained elusive we intended to produce high amounts of the brasilicardin backbone for semi synthesis and derivatization. Therefore, we used a metabolic engineering approach to increase heterologous production of brasilicardin in A. japonicum. Simultaneous heterologous expression of genes encoding the MVA pathway and expression of diterpenoid specific prenyltransferases were used to increase the provision of the isoprenoid precursor isopentenyl diphosphate (IPP) and to channel the precursor into the direction of diterpenoid biosynthesis. Both approaches contributed to an elevated heterologous production of the brasilicardin backbone, which can now be used as a starting point for semi synthesis of new brasilicardin congeners with better properties.
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Key Words
- 3HBA, 3-hydroxy-benzoate
- Aact, acetoacetyl CoA thiolase
- BraA, brasilicardin A
- BraB, brasilicardin B
- BraC, brasilicardin C
- BraC-agl, brasilicardin C aglycon
- BraD, brasilicardin D
- BraD-agl, brasilicardin D aglycon
- DMAPP, dimethylallyl diphosphate
- FPP, farnesyl diphosphate
- Fpps, farnesyl diphosphate synthase
- GGPP, geranylgeranyl diphosphate
- GPP, geranyl diphosphate
- Ggpps, geranylgeranyl diphosphate synthase
- GlcNAc, N-acetylglucosamine
- Gpps, geranyl diphosphate synthase
- IPP, isopentenyl diphosphate
- Idi, isopentenyl diphosphate synthase
- Isoprenoids
- MEP, Methylerythritol 4-phosphate
- MVA, mevalonate
- Mevalonate pathway
- Norcardia terpenica IFM0406
- Prenyltransferases
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Affiliation(s)
- Paul N Schwarz
- Microbiology/Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Luisa Roller
- Microbiology/Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Andreas Kulik
- Microbiology/Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls University Tübingen, Tübingen, Germany
| | - Wolfgang Wohlleben
- Microbiology/Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls University Tübingen, Tübingen, Germany.,German Centre for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
| | - Evi Stegmann
- Microbiology/Biotechnology, Interfaculty Institute of Microbiology and Infection Medicine Tübingen (IMIT), Eberhard Karls University Tübingen, Tübingen, Germany.,German Centre for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany
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5
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The type II isopentenyl Diphosphate:Dimethylallyl diphosphate isomerase (IDI-2): A model for acid/base chemistry in flavoenzyme catalysis. Arch Biochem Biophys 2017; 632:47-58. [PMID: 28577910 DOI: 10.1016/j.abb.2017.05.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 05/30/2017] [Accepted: 05/30/2017] [Indexed: 11/21/2022]
Abstract
The chemical versatility of the flavin coenzyme is nearly unparalleled in enzyme catalysis. An interesting illustration of this versatility can be found in the reaction catalyzed by the type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2) - an enzyme that interconverts the two essential isoprene units (isopentenyl pyrophosphate and dimethylallyl pyrophosphate) that are needed to initiate the biosynthesis of all isoprenoids. Over the past decade, a variety of biochemical, spectroscopic, structural and mechanistic studies of IDI-2 have provided mounting evidence that the flavin coenzyme of IDI-2 acts in a most unusual manner - as an acid/base catalyst to mediate a 1,3-proton addition/elimination reaction. While not entirely without precedent, IDI-2 is by far the most extensively studied flavoenzyme that employs flavin-mediated acid/base catalysis. Thus, IDI-2 serves as an important mechanistic model for understanding this often overlooked, but potentially widespread reactivity of flavin coenzymes. This review details the most pertinent studies that have contributed to the development of mechanistic proposals for this highly unusual flavoenzyme, and discusses future experiments that may be able to clarify remaining uncertainties in the chemical mechanism of IDI-2.
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Hou Q, Wang K, Xu F, Zhang W, Ji K, Liu Y. QM/MM studies of the type II isopentenyl diphosphate–dimethylallyl diphosphate isomerase demonstrate a novel role for the flavin coenzyme. RSC Adv 2017. [DOI: 10.1039/c6ra26397f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2) catalyzes the reversible isomerization of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP).
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Affiliation(s)
- Qianqian Hou
- Shandong Non-Metallic Materials Institute
- Jinan
- China
| | - Kang Wang
- Shandong Non-Metallic Materials Institute
- Jinan
- China
| | - Feng Xu
- Shandong Non-Metallic Materials Institute
- Jinan
- China
| | | | - Kejian Ji
- Shandong Non-Metallic Materials Institute
- Jinan
- China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan
- China
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Neti SS, Eckert DM, Poulter CD. Construction of Functional Monomeric Type 2 Isopentenyl Diphosphate:Dimethylallyl Diphosphate Isomerase. Biochemistry 2016; 55:4229-38. [PMID: 27379573 DOI: 10.1021/acs.biochem.6b00564] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Type 2 isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) in the isoprenoid biosynthetic pathway. The enzyme from Streptomyces pneumoniae (spIDI-2) is a homotetramer in solution with behavior, including a substantial increase in the rate of FMN reduction by NADPH in the presence of IPP, suggesting that substrate binding at one subunit alters the kinetic and binding properties of another. We now report the construction of catalytically active monomeric spIDI-2. The monomeric enzyme contains a single-point mutation (N37A) and a six-residue C-terminal deletion that preserves the secondary structure of the subunits in the wild-type (wt) homotetramer. UV-vis spectra of the enzyme-bound flavin mononucleotide (FMN) cofactor in FMNox, FMNred, and FMNred·IPP/DMAPP states are the same for monomeric and wt homotetrameric spIDI-2. The mutations in monomeric IDI-2 lower the melting temperature of the protein by 20 °C and reduce the binding affinities of FMN and IDI by 40-fold but have a minimal effect on kcat. Stopped-flow kinetic studies of monomeric spIDI-2 showed that the rate of reduction of FMN by NADH (k = 1.64 × 10(-3) s(-1)) is substantially faster when IPP is added to the monomeric enzyme (k = 0.57 s(-1)), similar to behavior seen for wt-spIDI-2. Our results indicate that cooperative interactions among subunits in the wt homotetramer are not responsible for the increased rate of reduction of spIDI-2·FMN by NADH, and two possible scenarios for the enhancement are suggested.
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Affiliation(s)
- Syam Sundar Neti
- Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - Debra M Eckert
- Department of Biochemistry, University of Utah School of Medicine , Salt Lake City, Utah 84112, United States
| | - C Dale Poulter
- Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States
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de Ruyck J, Brysbaert G, Blossey R, Lensink MF. Molecular docking as a popular tool in drug design, an in silico travel. Adv Appl Bioinform Chem 2016; 9:1-11. [PMID: 27390530 PMCID: PMC4930227 DOI: 10.2147/aabc.s105289] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
New molecular modeling approaches, driven by rapidly improving computational platforms, have allowed many success stories for the use of computer-assisted drug design in the discovery of new mechanism-or structure-based drugs. In this overview, we highlight three aspects of the use of molecular docking. First, we discuss the combination of molecular and quantum mechanics to investigate an unusual enzymatic mechanism of a flavoprotein. Second, we present recent advances in anti-infectious agents' synthesis driven by structural insights. At the end, we focus on larger biological complexes made by protein-protein interactions and discuss their relevance in drug design. This review provides information on how these large systems, even in the presence of the solvent, can be investigated with the outlook of drug discovery.
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Affiliation(s)
| | | | - Ralf Blossey
- University Lille, CNRS UMR8576 UGSF, Lille, France
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Janczak MW, Poulter CD. Kinetic and Binding Studies of Streptococcus pneumoniae Type 2 Isopentenyl Diphosphate:Dimethylallyl Diphosphate Isomerase. Biochemistry 2016; 55:2260-8. [PMID: 27003727 DOI: 10.1021/acs.biochem.6b00087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Type 2 isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2) converts isopentenyl diphosphate (IPP) to dimethylallyl diphosphate (DMAPP), the two fundamental building blocks of isoprenoid molecules. IDI-2 is found in many species of bacteria and is a potential antibacterial target since this isoform is non-homologous to the type 1 enzyme in Homo sapiens. IDI-2 requires a reduced flavin mononucleotide to form the catalytically active ternary complex, IDI-2·FMNH2·IPP. For IDI-2 from the pathogenic bacterium Streptococcus pneumoniae, the flavin can be treated kinetically as a dissociable cosubstrate in incubations with IPP and excess NADH. Under these conditions, the enzyme follows a modified sequential ordered mechanism where FMN adds before IPP. Interestingly, the enzyme shows sigmoidal behavior when incubated with IPP and NADH with varied concentrations of FMN in aerobic conditions. In contrast, sigmoidal behavior is not seen in incubations under anaerobic conditions where FMN is reduced to FMNH2 before the reaction is initiated by addition of IPP. Stopped-flow experiments revealed that FMN, whether bound to IDI-2 or without enzyme in solution, is slowly reduced in a pseudo-first-order reaction upon addition of excess NADH (k(red)(FMN) = 5.7 × 10(-3) s(-1) and k(red)(IDI-2·FMN) = 2.8 × 10(-3) s(-1)), while reduction of the flavin is rapid upon addition of NADH to a mixture of IDI-2·FMN, and IPP (k(red)(IDI-2·FMN·IPP) = 8.9 s(-1)). Similar experiments with dithionite as the reductant gave k(red)(FMN) = 221 s(-1) and k(red)(IDI-2·FMN) = 411 s(-1). Dithionite reduction of FMN in the IDI-2·FMN and IPP mixture was biphasic with k(red)(IDI-2·FMN·IPP (fast)) = 326 s(-1) and k(red)(IDI-2·FMN·IPP (slow)) = 6.9 s(-1) The pseudo-first-order rate constant for the slow component was similar to those for NADH reduction of the flavin in the IDI-2·FMN and IPP mixture and may reflect a rate-limiting conformational change in the enzyme.
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Affiliation(s)
- Matthew Walter Janczak
- Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States
| | - C Dale Poulter
- Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States
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10
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de Ruyck J, Janczak MW, Neti SS, Rothman SC, Schubert HL, Cornish RM, Matagne A, Wouters J, Poulter CD. Determination of kinetics and the crystal structure of a novel type 2 isopentenyl diphosphate: dimethylallyl diphosphate isomerase from Streptococcus pneumoniae. Chembiochem 2014; 15:1452-8. [PMID: 24910111 PMCID: PMC4215930 DOI: 10.1002/cbic.201402046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Indexed: 11/07/2022]
Abstract
Isopentenyl diphosphate isomerase (IDI) is a key enzyme in the isoprenoid biosynthetic pathway and is required for all organisms that synthesize isoprenoid metabolites from mevalonate. Type 1 IDI (IDI-1) is a metalloprotein that is found in eukaryotes, whereas the type 2 isoform (IDI-2) is a flavoenzyme found in bacteria that is completely absent from human. IDI-2 from the pathogenic bacterium Streptococcus pneumoniae was recombinantly expressed in Escherichia coli. Steady-state kinetic studies of the enzyme indicated that FMNH2 (KM =0.3 μM) bound before isopentenyl diphosphate (KM =40 μM) in an ordered binding mechanism. An X-ray crystal structure at 1.4 Å resolution was obtained for the holoenzyme in the closed conformation with a reduced flavin cofactor and two sulfate ions in the active site. These results helped to further approach the enzymatic mechanism of IDI-2 and, thus, open new possibilities for the rational design of antibacterial compounds against sequence-similar and structure-related pathogens such as Enterococcus faecalis or Staphylococcus aureus.
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Affiliation(s)
- Jerome de Ruyck
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112 (USA); Department of Chemistry, UNamur, 61 rue de Bruxelles, 5000 Namur (Belgium)
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11
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de Ruyck J, Schubert HL, Janczak MW, Poulter CD. Tetartohedral twinning in IDI-2 from Thermus thermophilus: crystallization under anaerobic conditions. Acta Crystallogr F Struct Biol Commun 2014; 70:347-9. [PMID: 24598924 PMCID: PMC3944699 DOI: 10.1107/s2053230x14002143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Accepted: 01/29/2014] [Indexed: 11/10/2022] Open
Abstract
Type-2 isopentenyl diphosphate isomerase (IDI-2) is a key flavoprotein involved in the biosynthesis of isoprenoids. Since fully reduced flavin mononucleotide (FMNH2) is needed for activity, it was decided to crystallize the enzyme under anaerobic conditions in order to understand how this reduced cofactor binds within the active site and interacts with the substrate isopentenyl diphosphate (IPP). In this study, the protein was expressed and purified under aerobic conditions and then reduced and crystallized under anaerobic conditions. Crystals grown by the sitting-drop vapour-diffusion method and then soaked with IPP diffracted to 2.1 Å resolution and belonged to the hexagonal space group P6322, with unit-cell parameters a = b = 133.3, c = 172.9 Å.
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Affiliation(s)
- Jerome de Ruyck
- Department of Chemistry, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium
- Department of Chemistry, University of Utah, 315 South 1400 East, Rm 2020, Salt Lake City, UT 84112, United States
| | - Heidi L. Schubert
- Department of Biochemistry, University of Utah School of Medicine, 15 North Medical Drive, Salt Lake City, UT 84112, USA
| | - Matthew W. Janczak
- Department of Chemistry, University of Utah, 315 South 1400 East, Rm 2020, Salt Lake City, UT 84112, United States
| | - C. Dale Poulter
- Department of Chemistry, University of Utah, 315 South 1400 East, Rm 2020, Salt Lake City, UT 84112, United States
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Affiliation(s)
| | - Salim Al-Babili
- BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia
| | - Eleanore T. Wurtzel
- The Graduate School and University Center, The City University of New York, New York, New York, USA
- Department of Biological Sciences, Lehman College, The City University of New York, Bronx, New York, USA
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13
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Zhao L, Chang WC, Xiao Y, Liu HW, Liu P. Methylerythritol phosphate pathway of isoprenoid biosynthesis. Annu Rev Biochem 2013; 82:497-530. [PMID: 23746261 DOI: 10.1146/annurev-biochem-052010-100934] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Isoprenoids are a class of natural products with more than 55,000 members. All isoprenoids are constructed from two precursors, isopentenyl diphosphate and its isomer dimethylallyl diphosphate. Two of the most important discoveries in isoprenoid biosynthetic studies in recent years are the elucidation of a second isoprenoid biosynthetic pathway [the methylerythritol phosphate (MEP) pathway] and a modified mevalonic acid (MVA) pathway. In this review, we summarize mechanistic insights on the MEP pathway enzymes. Because many isoprenoids have important biological activities, the need to produce them in sufficient quantities for downstream research efforts or commercial application is apparent. Recent advances in both MVA and MEP pathway-based synthetic biology are also illustrated by reviewing the landmark work of artemisinic acid and taxadien-5α-ol production through microbial fermentations.
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Affiliation(s)
- Lishan Zhao
- Amyris, Inc., Emeryville, California 94608, USA.
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Durchschein K, Wallner S, Macheroux P, Zangger K, Fabian WMF, Faber K. Unusual C=C bond isomerization of an α,β-unsaturated γ-butyrolactone catalysed by flavoproteins from the old yellow enzyme family. Chembiochem 2012; 13:2346-51. [PMID: 23024004 PMCID: PMC3533789 DOI: 10.1002/cbic.201200475] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Indexed: 12/02/2022]
Abstract
An unexpected, redox-neutral C=C bond isomerization of a γ-butyrolactone bearing an exo-methylene unit to the thermodynamically more favoured endo isomer (kcat = 0.076 s−1) catalysed by flavoproteins from the Old Yellow Enzyme family was discovered. Theoretical calculations and kinetic data support a mechanism through which the isomerization proceeds through FMN-mediated hydride addition onto exo-Cβ, followed by hydride abstraction from endo-Cβ′, which is in line with the well-established C=C bond bioreduction of OYEs. This new isomerase activity enriches the catalytic versatility of ene-reductases.
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Affiliation(s)
- Katharina Durchschein
- Organic & Bioorganic Chemistry, Department of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
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15
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Berthelot K, Estevez Y, Deffieux A, Peruch F. Isopentenyl diphosphate isomerase: A checkpoint to isoprenoid biosynthesis. Biochimie 2012; 94:1621-34. [DOI: 10.1016/j.biochi.2012.03.021] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Accepted: 03/27/2012] [Indexed: 11/25/2022]
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16
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Calveras J, Thibodeaux CJ, Mansoorabadi SO, Liu HW. Stereochemical studies of the type II isopentenyl diphosphate-dimethylallyl diphosphate isomerase implicate the FMN coenzyme in substrate protonation. Chembiochem 2012; 13:42-6. [PMID: 22135039 PMCID: PMC3454496 DOI: 10.1002/cbic.201100694] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Indexed: 11/07/2022]
Affiliation(s)
- Jordi Calveras
- Division of Medicinal Chemistry, College of Pharmacy, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, TX 78712, USA
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Covalent modification of reduced flavin mononucleotide in type-2 isopentenyl diphosphate isomerase by active-site-directed inhibitors. Proc Natl Acad Sci U S A 2011; 108:20461-6. [PMID: 22158896 DOI: 10.1073/pnas.1115749108] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Evidence for an unusual catalysis of protonation/deprotonation by a reduced flavin mononucleotide cofactor is presented for type-2 isopentenyl diphosphate isomerase (IDI-2), which catalyzes isomerization of the two fundamental building blocks of isoprenoid biosynthesis, isopentenyl diphosphate and dimethylallyl diphosphate. The covalent adducts formed between irreversible mechanism-based inhibitors, 3-methylene-4-penten-1-yl diphosphate or 3-oxiranyl-3-buten-1-yl diphosphate, and the flavin cofactor were investigated by X-ray crystallography and UV-visible spectroscopy. Both the crystal structures of IDI-2 binding the flavin-inhibitor adduct and the UV-visible spectra of the adducts indicate that the covalent bond is formed at C4a of flavin rather than at N5, which had been proposed previously. In addition, the high-resolution crystal structures of IDI-2-substrate complexes and the kinetic studies of new mutants confirmed that only the flavin cofactor can catalyze protonation of the substrates and suggest that N5 of flavin is most likely to be involved in proton transfer. These data provide support for a mechanism where the reduced flavin cofactor acts as a general acid/base catalyst and helps stabilize the carbocationic intermediate formed by protonation.
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18
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Heaps NA, Poulter CD. Type-2 isopentenyl diphosphate isomerase: evidence for a stepwise mechanism. J Am Chem Soc 2011; 133:19017-9. [PMID: 22047048 DOI: 10.1021/ja208331q] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Isopentenyl diphosphate isomerase (IDI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). These two molecules are the building blocks for construction of isoprenoid carbon skeletons in nature. Two structurally unrelated forms of IDI are known. A variety of studies support a proton addition/proton elimination mechanism for both enzymes. During studies with Thermus thermophilus IDI-2, we discovered that the olefinic hydrogens of a vinyl thiomethyl analogue of isopentenyl diphosphate exchanged with solvent when the enzyme was incubated with D(2)O without concomitant isomerization of the double bond. These results suggest that the enzyme-catalyzed isomerization reaction is not concerted.
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Affiliation(s)
- Nicole A Heaps
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112, USA
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19
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de Ruyck J, Wouters J, Poulter CD. Inhibition Studies on Enzymes Involved in Isoprenoid Biosynthesis: Focus on Two Potential Drug Targets: DXR and IDI-2 Enzymes. ACTA ACUST UNITED AC 2011; 7. [PMID: 24339799 DOI: 10.2174/157340811796575317] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Isoprenoid compounds constitute an immensely diverse group of acyclic, monocyclic and polycyclic compounds that play important roles in all living organisms. Despite the diversity of their structures, this plethora of natural products arises from only two 5-carbon precursors, isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). This review will discuss the enzymes in the mevalonate (MVA) and methylerythritol phosphate (MEP) biosynthetic pathways leading to IPP and DMAPP with a particular focus on MEP synthase (DXR) and IPP isomerase (IDI), which are potential targets for the development of antibiotic compounds. DXR is the second enzyme in the MEP pathway and the only one for which inhibitors with antimicrobial activity at pharmaceutically relevant concentrations are known. All of the published DXR inhibitors are fosmidomycin analogues, except for a few bisphosphonates with moderate inhibitory activity. These far, there are no other candidates that target DXR. IDI was first identified and characterised over 40 years ago (IDI-1) and a second convergently evolved isoform (IDI-2) was discovered in 2001. IDI-1 is a metalloprotein found in Eukarya and many species of Bacteria. Its mechanism has been extensively studied. In contrast, IDI-2 requires reduced flavin mononucleotide as a cofactor. The mechanism of action for IDI-2 is less well defined. This review will describe how lead inhibitors are being improved by structure-based drug design and enzymatic assays against DXR to lead to new drug families and how mechanistic probes are being used to address questions about the mechanisms of the isomerases.
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Affiliation(s)
- Jérôme de Ruyck
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, UT 84112, USA
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20
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Thibodeaux CJ, Chang WC, Liu HW. Linear free energy relationships demonstrate a catalytic role for the flavin mononucleotide coenzyme of the type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase. J Am Chem Soc 2010; 132:9994-6. [PMID: 20593767 DOI: 10.1021/ja104090m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2) catalyzes the reversible isomerization of the two ubiquitous isoprene units, isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP), which are required to initiate the biosynthesis of all isoprenoid compounds found in nature. The overall chemical transformation catalyzed by IDI-2 involves a net 1,3-proton addition/elimination reaction. Surprisingly, IDI-2 requires a reduced flavin mononucleotide (FMN) coenzyme to carry out this redox neutral isomerization. The exact function of FMN in catalysis has not yet been clearly defined. To provide mechanistic insight into the role of the reduced flavin in IDI-2 catalysis, several FMN analogues with altered electronic properties were chemoenzymatically prepared, and their effects on the kinetic properties of the IDI-2 catalyzed reaction were investigated. Linear free energy relationships (LFERs) between the electronic properties of the flavin and the steady state kinetic parameters of the IDI-2 catalyzed reaction were observed. The LFER studies are complemented with kinetic isotope effect studies and kinetic characterization of an active site mutant enzyme (Q154N). Cumulatively, the data presented in this work (and in other studies) suggest that the reduced FMN coenzyme of IDI-2 functions as an acid/base catalyst, with the N5 atom of the flavin likely playing a critical role in the deprotonation of IPP en route to DMAPP formation. Several potential chemical mechanisms involving the reduced flavin as an acid/base catalyst are presented and discussed.
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Affiliation(s)
- Christopher J Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, Department of Chemistry and Biochemistry, and Institute of Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA
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21
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Sharma NK, Pan JJ, Poulter CD. Type II isopentenyl diphosphate isomerase: probing the mechanism with alkyne/allene diphosphate substrate analogues. Biochemistry 2010; 49:6228-33. [PMID: 20560533 DOI: 10.1021/bi100844e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Isopentenyl diphosphate isomerase (IDI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the basic five-carbon building blocks of isoprenoid molecules. Two structurally unrelated classes of IDIs are known. Type I IPP isomerase (IDI-1) utilizes a divalent metal in a protonation-deprotonation reaction. In contrast, the type II enzyme (IDI-2) requires reduced flavin, raising the possibility that the reaction catalyzed by IDI-2 involves the net addition or abstraction of a hydrogen atom. As part of our studies of the mechanism of isomerization for IDI-2, we synthesized allene and alkyne substrate analogues for the enzyme. These molecules are predicted to be substantially less reactive toward proton addition than IPP and DMAPP but have similar reactivities toward hydrogen atom addition. This prediction was verified by calculations of gas-phase heats of reaction for addition of a proton and of a hydrogen atom to 1-butyne (3) and 1,2-butadiene (4) to form the 1-buten-2-yl carbocation and radical, respectively, and related affinities for 2-methyl-1-butene (5) and 2-methyl-2-butene (6) using G3MP2B3 and CBS-QB3 protocols. Alkyne 1-OPP and allene 2-OPP were not substrates for Thermus thermophilus IDI-2 or Escherichia coli IDI-1 but instead were competitive inhibitors. The experimental and computational results are consistent with a protonation-deprotonation mechanism for the enzyme-catalyzed isomerization of IPP and DMAPP.
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Affiliation(s)
- Nagendra K Sharma
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
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22
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Mialoundama AS, Heintz D, Jadid N, Nkeng P, Rahier A, Deli J, Camara B, Bouvier F. Characterization of plant carotenoid cyclases as members of the flavoprotein family functioning with no net redox change. PLANT PHYSIOLOGY 2010; 153:970-979. [PMID: 20460582 PMCID: PMC2899934 DOI: 10.1104/pp.110.155440] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Accepted: 05/08/2010] [Indexed: 05/28/2023]
Abstract
The later steps of carotenoid biosynthesis involve the formation of cyclic carotenoids. The reaction is catalyzed by lycopene beta-cyclase (LCY-B), which converts lycopene into beta-carotene, and by capsanthin-capsorubin synthase (CCS), which is mainly dedicated to the synthesis of kappa-cyclic carotenoids (capsanthin and capsorubin) but also has LCY-B activity. Although the peptide sequences of plant LCY-Bs and CCS contain a putative dinucleotide-binding motif, it is believed that these two carotenoid cyclases proceed via protic activation and stabilization of resulting carbocation intermediates. Using pepper (Capsicum annuum) CCS as a prototypic carotenoid cyclase, we show that the monomeric protein contains one noncovalently bound flavin adenine dinucleotide (FAD) that is essential for enzyme activity only in the presence of NADPH, which functions as the FAD reductant. The reaction proceeds without transfer of hydrogen from the dinucleotide cofactors to beta-carotene or capsanthin. Using site-directed mutagenesis, amino acids potentially involved in the protic activation were identified. Substitutions of alanine, lysine, and arginine for glutamate-295 in the conserved 293-FLEET-297 motif of pepper CCS or LCY-B abolish the formation of beta-carotene and kappa-cyclic carotenoids. We also found that mutations of the equivalent glutamate-196 located in the 194-LIEDT-198 domain of structurally divergent bacterial LCY-B abolish the formation of beta-carotene. The data herein reveal plant carotenoid cyclases to be novel enzymes that combine characteristics of non-metal-assisted terpene cyclases with those attributes typically found in flavoenzymes that catalyze reactions, with no net redox, such as type 2 isopentenyl diphosphate isomerase. Thus, FAD in its reduced form could be implicated in the stabilization of the carbocation intermediate.
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23
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Yu Q, Schaub P, Ghisla S, Al-Babili S, Krieger-Liszkay A, Beyer P. The lycopene cyclase CrtY from Pantoea ananatis (formerly Erwinia uredovora) catalyzes an FADred-dependent non-redox reaction. J Biol Chem 2010; 285:12109-20. [PMID: 20178989 PMCID: PMC2852950 DOI: 10.1074/jbc.m109.091843] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 02/22/2010] [Indexed: 11/06/2022] Open
Abstract
The cyclization of lycopene generates provitamin A carotenoids such as beta-carotene and paves the way toward the formation of cyclic xanthophylls playing distinct roles in photosynthesis and as precursors for regulatory molecules in plants and animals. The biochemistry of lycopene cyclization has been enigmatic, as the previously proposed acid-base catalysis conflicted with the possibility of redox catalysis as predicted by the presence of a dinucleotide binding site. We show that reduced FAD is the essential lycopene cyclase (CrtY) cofactor. Using flavin analogs, mass spectrometry, and mutagenesis, evidence was obtained based on which a catalytic mechanism relying on cryptic (net) electron transfer can be refuted. The role of reduced FAD is proposed to reside in the stabilization of a transition state carrying a (partial) positive charge or of a positively charged intermediate via a charge transfer interaction, acid-base catalysis serving as the underlying catalytic principle. Lycopene cyclase, thus, ranks among the novel class of non-redox flavoproteins, such as isopentenyl diphosphate:dimethylallyl diphosphate isomerase type 2 (IDI-2) that requires the reduced form of the cofactor.
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Affiliation(s)
- Qiuju Yu
- From the Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Patrick Schaub
- From the Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Sandro Ghisla
- the Department of Biology, University of Konstanz, D-78457 Konstanz, Germany, and
| | - Salim Al-Babili
- From the Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
| | - Anja Krieger-Liszkay
- the Commissariat á l'Energie Atomique, Institut de Biologie et Technologies de Saclay, CNRS Unité de Recherche Associée 2096, Service de Bioénergétique Biologie Structurale et Mécanisme, F-91191 Gif-sur-Yvette Cedex, France
| | - Peter Beyer
- From the Faculty of Biology, University of Freiburg, D-79104 Freiburg, Germany
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Unno H, Yamashita S, Ikeda Y, Sekiguchi SY, Yoshida N, Yoshimura T, Kusunoki M, Nakayama T, Nishino T, Hemmi H. New role of flavin as a general acid-base catalyst with no redox function in type 2 isopentenyl-diphosphate isomerase. J Biol Chem 2009; 284:9160-7. [PMID: 19158086 DOI: 10.1074/jbc.m808438200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using FMN and a reducing agent such as NAD(P)H, type 2 isopentenyl-diphosphate isomerase catalyzes isomerization between isopentenyl diphosphate and dimethylallyl diphosphate, both of which are elemental units for the biosynthesis of highly diverse isoprenoid compounds. Although the flavin cofactor is expected to be integrally involved in catalysis, its exact role remains controversial. Here we report the crystal structures of the substrate-free and complex forms of type 2 isopentenyl-diphosphate isomerase from the thermoacidophilic archaeon Sulfolobus shibatae, not only in the oxidized state but also in the reduced state. Based on the active-site structures of the reduced FMN-substrate-enzyme ternary complexes, which are in the active state, and on the data from site-directed mutagenesis at highly conserved charged or polar amino acid residues around the active site, we demonstrate that only reduced FMN, not amino acid residues, can catalyze proton addition/elimination required for the isomerase reaction. This discovery is the first evidence for this long suspected, but previously unobserved, role of flavins just as a general acid-base catalyst without playing any redox roles, and thereby expands the known functions of these versatile coenzymes.
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Affiliation(s)
- Hideaki Unno
- Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, Bunkyo-machi, Nagasaki, Nagasaki 852-8521, Japan
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25
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Liavonchanka A, Rudolph MG, Tittmann K, Hamberg M, Feussner I. On the mechanism of a polyunsaturated fatty acid double bond isomerase from Propionibacterium acnes. J Biol Chem 2009; 284:8005-12. [PMID: 19164287 DOI: 10.1074/jbc.m809060200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The catalytic mechanism of Propionibacterium acnes polyunsaturated fatty acid isomerase (PAI) is explored by kinetic, spectroscopic, and thermodynamic studies. The PAI-catalyzed double bond isomerization takes place by selective removal of the pro-R hydrogen from C-11 followed by suprafacial transfer of this hydrogen to C-9 as shown by conversion of C-9-deuterated substrate isotopologs. Data on the midpoint potential, photoreduction, and cofactor replacement suggest PAI to operate via an ionic mechanism with the formation of FADH(2) and linoleic acid carbocation as intermediates. In line with this proposal, no radical intermediates were detected neither by stopped flow absorption nor by EPR spectroscopy. The substrate preference toward free fatty acids is determined by the interaction between Arg-88 and Phe-193, and the reaction rate is strongly affected by replacement of these amino acids, indicating that the efficiency of the hydrogen transfer relies on a fixed distance between the free carboxyl group and the N-5 atom of FAD. Combining data obtained for PAI from the structural studies and experiments described here suggests that at least two different prototypical active site geometries exist among polyunsaturated fatty acid double bond isomerases.
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Affiliation(s)
- Alena Liavonchanka
- Department for Plant Biochemistry, Albrecht-von-Haller-Institute for Plant Sciences, Goettingen, Germany
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26
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Liavonchanka A, Feussner I. Biochemistry of PUFA double bond isomerases producing conjugated linoleic acid. Chembiochem 2008; 9:1867-72. [PMID: 18655062 DOI: 10.1002/cbic.200800141] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The biotransformation of linoleic acid (LA) into conjugated linoleic acid (CLA) by microorganisms is a potentially useful industrial process. In most cases, however, the identities of proteins involved and the details of enzymatic activity regulation are far from clear. Here we summarize available data on the reaction mechanisms of CLA-producing enzymes characterized until now, from Butyrivibrio fibrisolvens, Lactobacillus acidophilus, Ptilota filicina, and Propionibacterium acnes. A general feature of enzymatic LA isomerization is the protein-assisted abstraction of an aliphatic hydrogen atom from position C-11, while the role of flavin as cofactor for the double bond activation in CLA-producing enzymes is also discussed with regard to the recently published three-dimensional structure of an isomerase from P. acnes. Combined data from structural studies, isotopic labeling experiments, and sequence comparison suggest that at least two different prototypical active site geometries occur among polyunsaturated fatty acid (PUFA) double bond isomerases.
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Affiliation(s)
- Alena Liavonchanka
- Georg August University, Albrecht von Haller Institute for Plant Sciences, Department of Plant Biochemistry, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
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27
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Eoh H, Brennan PJ, Crick DC. The Mycobacterium tuberculosis MEP (2C-methyl-d-erythritol 4-phosphate) pathway as a new drug target. Tuberculosis (Edinb) 2008; 89:1-11. [PMID: 18793870 DOI: 10.1016/j.tube.2008.07.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 07/15/2008] [Accepted: 07/23/2008] [Indexed: 10/21/2022]
Abstract
Tuberculosis (TB) is still a major public health problem, compounded by the human immunodeficiency virus (HIV)-TB co-infection and recent emergence of multidrug-resistant (MDR) and extensively drug resistant (XDR)-TB. Novel anti-TB drugs are urgently required. In this context, the 2C-methyl-d-erythritol 4-phosphate (MEP) pathway of Mycobacterium tuberculosis has drawn attention; it is one of several pathways vital for M. tuberculosis viability and the human host lacks homologous enzymes. Thus, the MEP pathway promises bacterium-specific drug targets and the potential for identification of lead compounds unencumbered by target-based toxicity. Indeed, fosmidomycin is now known to inhibit the second step in the MEP pathway. This review describes the cardinal features of the main enzymes of the MEP pathway in M. tuberculosis and how these can be manipulated in high throughput screening campaigns in the search for new anti-infectives against TB.
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Affiliation(s)
- Hyungjin Eoh
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA.
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28
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de Ruyck J, Pouyez J, Rothman SC, Poulter D, Wouters J. Crystal structure of type 2 isopentenyl diphosphate isomerase from Thermus thermophilus in complex with inorganic pyrophosphate. Biochemistry 2008; 47:9051-3. [PMID: 18693754 DOI: 10.1021/bi801159x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The N-terminal region is stabilized in the crystal structure of Thermus thermophilus type 2 isopentenyl diphosphate isomerase in complex with inorganic pyrophosphate, providing new insights about the active site and the catalytic mechanism of the enzyme. The PP i moiety is located near the conserved residues, H10, R97, H152, Q157, E158, and W219, and the flavin cofactor. The putative active site of isopentenyl diphosphate isomerase 2 provides interactions for stabilizing a carbocationic intermediate similar to those that stabilize the intermediate in the well-established protonation-deprotonation mechanism of isopentenyl diphosphate isomerase 1.
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Affiliation(s)
- Jérôme de Ruyck
- Department of Chemistry, University of Namur, Namur, Belgium.
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29
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Rothman SC, Johnston JB, Lee S, Walker JR, Poulter CD. Type II isopentenyl diphosphate isomerase: irreversible inactivation by covalent modification of flavin. J Am Chem Soc 2008; 130:4906-13. [PMID: 18345677 DOI: 10.1021/ja7108954] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Isopentenyl diphosphate isomerase (IDI) catalyzes the interconversion of isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP), the basic building blocks of isoprenoid molecules. Two structurally unrelated classes of IDI are known. Type I IPP isomerase (IDI-1) utilizes a divalent metal in a protonation-deprotonation reaction; whereas, the type II enzyme (IDI-2) requires reduced flavin. Epoxy, diene, and fluorinated substrate analogues, irreversible inhibitors of IDI-1, were analyzed as mechanistic probes for IDI-2. 3,4-Oxido-3-methyl-1-butyl diphosphate (eIPP), 3-methylene-4-penten-1-yl diphosphate (vIPP), and 3-(fluoromethyl)-3-buten-1-yl diphosphate (fmIPP) inactivate IDI-2 through formation of covalent adducts with the reduced flavin. UV-visible spectra of the inactivated complexes are consistent with modification of the isoalloxazine ring at position N5. vIPP and fmIPP are also alternate substrates with isomerization competing with alkylation of the flavin cofactor. (Z)-3-(Fluoromethyl)-2-buten-1-yl diphosphate ((Z)-fmDMAPP) and (Z)-3-(difluoromethyl)-2-buten-1-yl diphosphate ((Z)-dfmDMAPP) are alternate substrates, which are isomerized to the corresponding IPP derivatives. The rates of isomerization of fmIPP and (Z)-fmDMAPP are approximately 50-fold less than IPP and DMAPP, respectively. dfmIPP is not an irreversible inhibitor. These studies indicate that the irreversible inhibitors inactivate the reduced flavin required for catalysis by electrophilic alkylation and are consistent with a protonation-deprotonation mechanism for the isomerization catalyzed by IDI-2.
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Affiliation(s)
- Steven C Rothman
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
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30
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Thibodeaux CJ, Mansoorabadi SO, Kittleman W, Chang WC, Liu HW. Evidence for the involvement of acid/base chemistry in the reaction catalyzed by the type II isopentenyl diphosphate/dimethylallyl diphosphate isomerase from Staphylococcus aureus. Biochemistry 2008; 47:2547-58. [PMID: 18229948 DOI: 10.1021/bi701467g] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The type II isopentenyl diphosphate/dimethylallyl diphosphate isomerase (IDI-2) is a flavin mononucleotide (FMN)-dependent enzyme that catalyzes the reversible isomerization of isopentenyl pyrophosphate (IPP) to dimethylallyl pyrophosphate (DMAPP), a reaction with no net change in redox state of the coenzyme or substrate. Here, UV-vis spectral analysis of the IDI-2 reaction revealed the accumulation of a reduced neutral dihydroflavin intermediate when the reduced enzyme was incubated with IPP or DMAPP. When IDI-2 was reconstituted with 1-deazaFMN and 5-deazaFMN, similar reduced neutral forms of the deazaflavin analogues were observed in the presence of IPP. Single turnover stopped-flow absorbance experiments indicated that this flavin intermediate formed and decayed at kinetically competent rates in the pre-steady-state and, thus, most likely represents a true intermediate in the catalytic cycle. UV-vis spectra of the reaction mixtures reveal trace amounts of a neutral semiquinone, but evidence for the presence of IPP-based radicals could not be obtained by EPR spectroscopy. Rapid-mix chemical quench experiments show no burst in DMAPP formation, suggesting that the rate determining step in the forward direction (IPP to DMAPP) occurs prior to DMAPP formation. A solvent deuterium kinetic isotope effect (D2OVmax = 1.5) was measured on vo in steady-state kinetic experiments at saturating substrate concentrations. A substrate deuterium kinetic isotope effect was also measured on the initital velocity (DVmax = 1.8) and on the decay rate of the flavin intermediate (Dks = 2.3) in single-turnover stopped-flow experiments using (R)-[2-2H]-IPP. Taken together, these data suggest that the C2-H bond of IPP is cleaved in the rate determining step and that general acid/base catalysis may be involved during turnover. Possible mechanisms for the IDI-2 catalyzed reaction are presented and discussed in terms of the available X-ray crystal structures.
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Affiliation(s)
- Christopher J Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, Department of Chemistry and Biochemistry, and Institute of Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A1935, Austin, Texas 78712, USA
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31
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Grochowski LL, White RH. Promiscuous anaerobes: new and unconventional metabolism in methanogenic archaea. Ann N Y Acad Sci 2007; 1125:190-214. [PMID: 18096851 DOI: 10.1196/annals.1419.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The development of an oxygenated atmosphere on earth resulted in the polarization of life into two major groups, those that could live in the presence of oxygen and those that could not-the aerobes and the anaerobes. The evolution of aerobes from the earliest anaerobic prokaryotes resulted in a variety of metabolic adaptations. Many of these adaptations center on the need to sustain oxygen-sensitive reactions and cofactors to function in the new oxygen-containing atmosphere. Still other metabolic pathways that were not sensitive to oxygen also diverged. This is likely due to the physical separation of the organisms, based on their ability to live in the presence of oxygen, which allowed for the independent evolution of the pathways. Through the study of metabolic pathways in anaerobes and comparison to the more established pathways from aerobes, insight into metabolic evolution can be gained. This, in turn, can allow for extra- polation to those metabolic pathways occurring in the Last Universal Common Ancestor (LUCA). Some of the unique and uncanonical metabolic pathways that have been identified in the archaea with emphasis on the biochemistry of an obligate anaerobic methanogen, Methanocaldococcus jannaschii are reviewed.
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Affiliation(s)
- Laura L Grochowski
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA
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32
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Walker JR, Rothman SC, Poulter CD. Synthesis and evaluation of substrate analogues as mechanism-based inhibitors of type II isopentenyl diphosphate isomerase. J Org Chem 2007; 73:726-9. [PMID: 18088143 DOI: 10.1021/jo702061d] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Type 2 isopentenyl diphosphate isomerase (IDI-2), which catalyzes the interconversion of isopentenyl diphosphate and dimethylallyl diphosphate, contains a tightly bound molecule of FMN. To probe the mechanism of the reaction, cyclopropyl and epoxy substrate analogues, designed to be mechanism-based irreversible inhibitors, were synthesized and evaluated with IDI-2 from Thermus thermophilus. The cyclopropyl analogues were alternative substrates. The epoxy analogue was an irreversible inhibitor, with kI = 0.37 +/- 0.07 min(-1) and KI = 1.4 +/- 0.3 microM. LC-MS studies revealed formation of an epoxide-FMN adduct.
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Affiliation(s)
- Joel R Walker
- Department of Chemistry, University of Utah, 315 South 1400 East RM 2020, Salt Lake City, Utah 84112, USA
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Overexpression, physicochemical characterization, and modeling of a hyperthermophilic pyrococcus furiosus type 2 IPP isomerase. Proteins 2007; 71:1699-707. [DOI: 10.1002/prot.21863] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Mansoorabadi SO, Thibodeaux CJ, Liu HW. The diverse roles of flavin coenzymes--nature's most versatile thespians. J Org Chem 2007; 72:6329-42. [PMID: 17580897 PMCID: PMC2519020 DOI: 10.1021/jo0703092] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Flavin coenzymes play a variety of roles in biological systems. This Perspective highlights the chemical versatility of flavins by reviewing research on five flavoenzymes that have been studied in our laboratory. Each of the enzymes discussed in this review [the acyl-CoA dehydrogenases (ACDs), CDP-6-deoxy-l-threo-d-glycero-4-hexulose-3-dehydrase reductase (E3), CDP-4-aceto-3,6-dideoxygalactose synthase (YerE), UDP-galactopyranose mutase (UGM), and type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase (IDI-2)] utilizes flavin in a distinct role. In particular, the catalytic mechanisms of two of these enzymes, UGM and IDI-2, may involve novel flavin chemistry.
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Affiliation(s)
- Steven O. Mansoorabadi
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
| | - Christopher J. Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, TX 78712, USA
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Kittleman W, Thibodeaux CJ, Liu YN, Zhang H, Liu HW. Characterization and mechanistic studies of type II isopentenyl diphosphate:dimethylallyl diphosphate isomerase from Staphylococcus aureus. Biochemistry 2007; 46:8401-13. [PMID: 17585782 PMCID: PMC2515275 DOI: 10.1021/bi700286a] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The recently identified type II isopentenyl diphosphate (IPP):dimethylallyl diphosphate (DMAPP) isomerase (IDI-2) is a flavoenzyme that requires FMN and NAD(P)H for activity. IDI-2 is an essential enzyme for the biosynthesis of isoprenoids in several pathogenic bacteria including Staphylococcus aureus, Streptococcus pneumoniae, and Enterococcus faecalis, and thus is considered as a potential new drug target to battle bacterial infections. One notable feature of the IDI-2 reaction is that there is no net change in redox state between the substrate (IPP) and product (DMAPP), indicating that the FMN cofactor must start and finish each catalytic cycle in the same redox state. Here, we report the characterization and initial mechanistic studies of the S. aureus IDI-2. The steady-state kinetic analyses under aerobic and anaerobic conditions show that FMN must be reduced to be catalytically active and the overall IDI-2 reaction is O2-sensitive. Interestingly, our results demonstrate that NADPH is needed only in catalytic amounts to activate the enzyme for multiple turnovers of IPP to DMAPP. The hydride transfer from NAD(P)H to reduce FMN is determined to be pro-S stereospecific. Photoreduction and oxidation-reduction potential studies reveal that the S. aureus IDI-2 can stabilize significant amounts of the neutral FMN semiquinone. In addition, reconstitution of apo-IDI-2 with 5-deazaFMN resulted in a dead enzyme, whereas reconstitution with 1-deazaFMN led to the full recovery of enzyme activity. Taken together, these studies appear to support a catalytic mechanism in which the reduced flavin coenzyme mediates a single electron transfer to and from the IPP substrate during catalysis.
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Affiliation(s)
- William Kittleman
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712
| | - Christopher J. Thibodeaux
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712
| | - Yung-nan Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712
| | - Hua Zhang
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712
| | - Hung-wen Liu
- Division of Medicinal Chemistry, College of Pharmacy, and Department of Chemistry and Biochemistry, University of Texas, Austin, Texas 78712
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Johnston JB, Walker JR, Rothman SC, Poulter CD. Type-2 isopentenyl diphosphate isomerase. Mechanistic studies with cyclopropyl and epoxy analogues. J Am Chem Soc 2007; 129:7740-1. [PMID: 17547410 PMCID: PMC2494526 DOI: 10.1021/ja072501r] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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