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Dulin CC, Sharma P, Frigo L, Voehler MW, Iverson TM, Bachmann BO. EvdS6 is a bifunctional decarboxylase from the everninomicin gene cluster. J Biol Chem 2023:104893. [PMID: 37286037 PMCID: PMC10338323 DOI: 10.1016/j.jbc.2023.104893] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/25/2023] [Accepted: 05/29/2023] [Indexed: 06/09/2023] Open
Abstract
The everninomicins are bacterially produced antibiotic octasaccharides characterized by the presence of two interglycosidic spirocyclic ortho-δ-lactone (orthoester) moieties. The terminating G- and H-ring sugars, L-lyxose and C-4 branched sugar β-D-eurekanate, are proposed to be biosynthetically derived from nucleotide diphosphate pentose sugar pyranosides; however, the identity of these precursors and their biosynthetic origin remain to be determined. Herein we identify a new glucuronic acid decarboxylase from Micromonospora belonging to the superfamily of short-chain dehydrogenase/reductase enzymes, EvdS6. Biochemical characterization demonstrated that EvdS6 is an NAD+-dependent bifunctional enzyme that produces a mixture of two products, differing in the sugar C-4 oxidation state. This product distribution is atypical for glucuronic acid decarboxylating enzymes, most of which favor production of the reduced sugar and a minority of which favor release of the oxidized product. Spectroscopic and stereochemical analysis of reaction products revealed that the first product released is the oxidatively produced 4-keto-D-xylose and the second product is the reduced D-xylose. X-ray crystallographic analysis of EvdS6 at 1.51 Å resolution with bound co-factor and TDP demonstrated that the overall geometry of the EvdS6 active site is conserved with other SDR enzymes and enabled studies probing structural determinants for the reductive half of the net neutral catalytic cycle. Critical active site threonine and aspartate residues were unambiguously identified as essential in the reductive step of the reaction and resulted in enzyme variants producing almost exclusively the keto sugar. This work defines potential precursors for the G-ring L-lyxose and resolves likely origins of the H-ring β-D-eurekanate sugar precursor.
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Affiliation(s)
- Callie C Dulin
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Pankaj Sharma
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Laura Frigo
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Markus W Voehler
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - T M Iverson
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Brian O Bachmann
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA; Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
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de Visser SP, Mukherjee G, Ali HS, Sastri CV. Local Charge Distributions, Electric Dipole Moments, and Local Electric Fields Influence Reactivity Patterns and Guide Regioselectivities in α-Ketoglutarate-Dependent Non-heme Iron Dioxygenases. Acc Chem Res 2022; 55:65-74. [PMID: 34915695 DOI: 10.1021/acs.accounts.1c00538] [Citation(s) in RCA: 37] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Non-heme iron dioxygenases catalyze vital processes for human health related to the biosynthesis of essential products and the biodegradation of toxic metabolites. Often the natural product biosyntheses by these non-heme iron dioxygenases is highly regio- and chemoselective, which are commonly assigned to tight substrate-binding and positioning. However, recent high-level computational modeling has shown that substrate-binding and positioning is only part of the story and long-range electrostatic interactions can play a major additional role.In this Account, we review and summarize computational viewpoints on the high regio- and chemoselectivity of α-ketoglutarate-dependent non-heme iron dioxygenases and how external perturbations affect the catalysis. In particular, studies from our groups have shown that often a regioselectivity in enzymes can be accomplished by stabilization of the rate-determining transition state for the reaction through external charges, electric dipole moments, or local electric field effects. Furthermore, bond dissociation energies in molecules are shown to be influenced by an electric field effect, and through targeting a specific bond in an electric field, this can lead to an unusually specific reaction. For instance, in the carbon-induced starvation protein, we studied two substrate-bound conformations and showed that regardless of what C-H bond of the substrate is closest to the iron(IV)-oxo oxidant, the lowest hydrogen atom abstraction barrier is always for the pro-S C2-H abstraction due to an induced dipole moment of the protein that weakens this bond. In another example of the hygromycin biosynthesis enzyme, an oxidative ring-closure reaction in the substrate forms an ortho-δ-ester ring. Calculations on this enzyme show that the selectivity is guided by a protonated lysine residue in the active site that, through its positive charge, triggers a low energy hydrogen atom abstraction barrier. A final set of examples in this Account discuss the viomycin biosynthesis enzyme and the 2-(trimethylammonio)ethylphosphonate dioxygenase (TmpA) enzyme. Both of these enzymes are shown to possess a significant local dipole moment and local electric field effect due to charged residues surrounding the substrate and oxidant binding pockets. The protein dipole moment and local electric field strength changes the C-H bond strengths of the substrate as compared to the gas-phase triggers the regioselectivity of substrate activation. In particular, we show that in the gas phase and in a protein environment C-H bond strengths are different due to local electric dipole moments and electric field strengths. These examples show that enzymes have an intricately designed structure that enables a chemical reaction under ambient conditions through the positioning of positively and negatively charged residues that influence and enhance reaction mechanisms. These computational insights create huge possibilities in bioengineering to apply local electric field and dipole moments in proteins to achieve an unusual selectivity and specificity and trigger a fit-for-purpose biocatalyst for unique biotransformations.
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Affiliation(s)
- Sam P. de Visser
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India
| | - Gourab Mukherjee
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India
| | - Hafiz Saqib Ali
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Chivukula V. Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, 781039 Assam, India
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Ali HS, Henchman RH, Visser SP. Mechanism of Oxidative Ring‐Closure as Part of the Hygromycin Biosynthesis Step by a Nonheme Iron Dioxygenase. ChemCatChem 2021. [DOI: 10.1002/cctc.202100393] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Hafiz Saqib Ali
- Manchester Institute of Biotechnology The University of Manchester 131 Princess Street Manchester M1 7DN UK
- Department of Chemistry The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Richard H. Henchman
- Manchester Institute of Biotechnology The University of Manchester 131 Princess Street Manchester M1 7DN UK
- Department of Chemistry The University of Manchester Oxford Road Manchester M13 9PL UK
| | - Sam P. Visser
- Manchester Institute of Biotechnology The University of Manchester 131 Princess Street Manchester M1 7DN UK
- Department of Chemical Engineering and Analytical Science The University of Manchester Oxford Road Manchester M13 9PL UK
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Zhang JH, Pan CL, Zhang HH, Xu PF, Luo YC. Sc(OTf) 3 catalyzed [3 + 2]-annulation reaction of donor–acceptor aziridines with methylene exo-glycals: synthesis of chiral carbohydrate-spiro-heterocycles. Org Chem Front 2021. [DOI: 10.1039/d1qo00228g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A Sc(OTf)3 catalyzed [3 + 2]-annulation reaction between D–A N-tosyl aziridines and methylene exo-glycals was developed for the synthesis of carbohydrate-spiro-heterocycles.
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Affiliation(s)
- Jie-Hui Zhang
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou
- P. R. China
| | - Cheng-Lin Pan
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou
- P. R. China
| | - Huan-Huan Zhang
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou
- P. R. China
| | - Peng-Fei Xu
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou
- P. R. China
| | - Yong-Chun Luo
- State Key Laboratory of Applied Organic Chemistry
- College of Chemistry and Chemical Engineering
- Lanzhou University
- Lanzhou
- P. R. China
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Limbrick EM, Yñigez-Gutierrez AE, Dulin CC, Derewacz DK, Spraggins JM, McCulloch KM, Iverson TM, Bachmann BO. Methyltransferase Contingencies in the Pathway of Everninomicin D Antibiotics and Analogues. Chembiochem 2020; 21:3349-3358. [PMID: 32686210 DOI: 10.1002/cbic.202000305] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 07/17/2020] [Indexed: 12/11/2022]
Abstract
Everninomicins are orthoester oligosaccharide antibiotics with potent activity against multidrug-resistant bacterial pathogens. Everninomicins act by disrupting ribosomal assembly in a distinct region in comparison to clinically prescribed drugs. We employed microporous intergeneric conjugation with Escherichia coli to manipulate Micromonospora for targeted gene-replacement studies of multiple putative methyltransferases across the octasaccharide scaffold of everninomicin effecting the A1 , C, F, and H rings. Analyses of gene-replacement and genetic complementation mutants established the mutability of the everninomicin scaffold through the generation of 12 previously unreported analogues and, together with previous results, permitted assignment of the ten methyltransferases required for everninomicin biosynthesis. The in vitro activity of A1 - and H-ring-modifying methyltransferases demonstrated the ability to catalyze late-stage modification of the scaffold on an A1 -ring phenol and H-ring C-4' hydroxy moiety. Together these results establish the potential of the everninomicin scaffold for modification through mutagenesis and in vitro modification of advanced biosynthetic intermediates.
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Affiliation(s)
- Emilianne M Limbrick
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Ctr, Nashville, TN 37235, USA.,Department of Chemistry, Mercer University, 1501 Mercer University Drive, Macon, GA 31207, USA
| | | | - Callie C Dulin
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Ctr, Nashville, TN 37235, USA
| | - Dagmara K Derewacz
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Ctr, Nashville, TN 37235, USA
| | - Jeffrey M Spraggins
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Ctr, Nashville, TN 37235, USA.,Department of Biochemistry, Vanderbilt University School of Medicine, 607 Light Hall, Nashville, TN 37205, USA.,Mass Spectrometry Research Center, Vanderbilt University School of Medicine, 465 21st Ave S, Nashville, TN 37240, USA
| | - Kathryn M McCulloch
- Department of Pharmacology, Vanderbilt University 7124 MRBIII, 465 21st Ave S, Nashville, TN 37232, USA.,Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, 3801 West Temple Ave, Pomona, CA 91768, USA
| | - T M Iverson
- Department of Biochemistry, Vanderbilt University School of Medicine, 607 Light Hall, Nashville, TN 37205, USA.,Department of Pharmacology, Vanderbilt University 7124 MRBIII, 465 21st Ave S, Nashville, TN 37232, USA.,Vanderbilt Institute of Chemical Biology.,Vanderbilt Center for Structural Biology
| | - Brian O Bachmann
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Ctr, Nashville, TN 37235, USA.,Department of Biochemistry, Vanderbilt University School of Medicine, 607 Light Hall, Nashville, TN 37205, USA.,Department of Pharmacology, Vanderbilt University 7124 MRBIII, 465 21st Ave S, Nashville, TN 37232, USA.,Vanderbilt Institute of Chemical Biology
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Affiliation(s)
- Zohreh Nazarian
- Faculty of Chemistry and Petroleum SciencesShahid Beheshti University, District 1 Daneshjou Boulevard 1983969411 Tehran Tehran Province Iran P.O. Box: 1983963113
| | - Minoo Dabiri
- Faculty of Chemistry and Petroleum SciencesShahid Beheshti University, District 1 Daneshjou Boulevard 1983969411 Tehran Tehran Province Iran P.O. Box: 1983963113
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Rajakovich LJ, Pandelia ME, Mitchell AJ, Chang WC, Zhang B, Boal AK, Krebs C, Bollinger JM. A New Microbial Pathway for Organophosphonate Degradation Catalyzed by Two Previously Misannotated Non-Heme-Iron Oxygenases. Biochemistry 2019; 58:1627-1647. [PMID: 30789718 PMCID: PMC6503667 DOI: 10.1021/acs.biochem.9b00044] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The assignment of biochemical functions to hypothetical proteins is challenged by functional diversification within many protein structural superfamilies. This diversification, which is particularly common for metalloenzymes, renders functional annotations that are founded solely on sequence and domain similarities unreliable and often erroneous. Definitive biochemical characterization to delineate functional subgroups within these superfamilies will aid in improving bioinformatic approaches for functional annotation. We describe here the structural and functional characterization of two non-heme-iron oxygenases, TmpA and TmpB, which are encoded by a genomically clustered pair of genes found in more than 350 species of bacteria. TmpA and TmpB are functional homologues of a pair of enzymes (PhnY and PhnZ) that degrade 2-aminoethylphosphonate but instead act on its naturally occurring, quaternary ammonium analogue, 2-(trimethylammonio)ethylphosphonate (TMAEP). TmpA, an iron(II)- and 2-(oxo)glutarate-dependent oxygenase misannotated as a γ-butyrobetaine (γbb) hydroxylase, shows no activity toward γbb but efficiently hydroxylates TMAEP. The product, ( R)-1-hydroxy-2-(trimethylammonio)ethylphosphonate [( R)-OH-TMAEP], then serves as the substrate for the second enzyme, TmpB. By contrast to its purported phosphohydrolytic activity, TmpB is an HD-domain oxygenase that uses a mixed-valent diiron cofactor to enact oxidative cleavage of the C-P bond of its substrate, yielding glycine betaine and phosphate. The high specificities of TmpA and TmpB for their N-trimethylated substrates suggest that they have evolved specifically to degrade TMAEP, which was not previously known to be subject to microbial catabolism. This study thus adds to the growing list of known pathways through which microbes break down organophosphonates to harvest phosphorus, carbon, and nitrogen in nutrient-limited niches.
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Affiliation(s)
- Lauren J. Rajakovich
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Present address: Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
| | - Maria-Eirini Pandelia
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Present address: Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02453, United States
| | - Andrew J. Mitchell
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Present address: Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142
| | - Wei-chen Chang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Present address: Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Bo Zhang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Present address: REG Life Sciences, LLC, South San Francisco, California 94080
| | - Amie K. Boal
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - J. Martin Bollinger
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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