1
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Burgener S, Dačević B, Zhang X, Ward TR. Binding Interactions and Inhibition Mechanisms of Gold Complexes in Thiamine Diphosphate-Dependent Enzymes. Biochemistry 2023; 62:3303-3311. [PMID: 37931174 DOI: 10.1021/acs.biochem.3c00376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2023]
Abstract
Thiamine diphosphate (ThDP)-dependent enzymes possess the unique ability to generate a carbene within their active site. In this study, we sought to harness this carbene to produce a Au(I) N-heterocyclic complex directly in the active site of ThDP enzymes, thereby establishing a novel platform for artificial metalloenzymes. Because direct metalation of ThDP proved challenging, we synthesized a ThDP mimic that acts as a competitive inhibitor with a high affinity (Ki = 1.5 μM). Upon metalation with Au(I), we observed that the complex became a more potent inhibitor (Ki = 0.7 μM). However, detailed analysis of the inhibition mode, native mass spectrometry, and size exclusion experiments revealed that the complex does not bind specifically to the active site of ThDP enzymes. Instead, it exhibits unspecific binding and exceeds the 1:1 stoichiometry. Similar binding patterns were observed for other Au(I) species. These findings prompt an important question regarding the inherent propensity of ThDP enzymes to bind strongly to Au. If this phenomenon holds true, it could pave the way for the development of Au-based drugs targeting these enzymes.
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Affiliation(s)
- Simon Burgener
- Department of Chemistry, University of Basel, Mattenstrasse 24a, BPR 1096 4058, Basel, Switzerland
| | - Bratislav Dačević
- Department of Chemistry, University of Basel, Mattenstrasse 24a, BPR 1096 4058, Basel, Switzerland
| | - Xiang Zhang
- Department of Chemistry, University of Basel, Mattenstrasse 24a, BPR 1096 4058, Basel, Switzerland
| | - Thomas R Ward
- Department of Chemistry, University of Basel, Mattenstrasse 24a, BPR 1096 4058, Basel, Switzerland
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2
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Uranga J, Rabe von Pappenheim F, Tittmann K, Mata RA. Dynamic Protonation States Underlie Carbene Formation in ThDP-Dependent Enzymes: A Theoretical Study. J Phys Chem B 2023; 127. [PMID: 37748048 PMCID: PMC10688766 DOI: 10.1021/acs.jpcb.3c03137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 09/09/2023] [Indexed: 09/27/2023]
Abstract
The activation mechanism of thiamine diphosphate (ThDP) in enzymes has long been the subject of intense research and controversial discussion. Particularly contentious is the formation of a carbene intermediate, the first one observed in an enzyme. For the formation of the carbene to take place, both intramolecular and intermolecular proton transfer pathways have been proposed. However, the physiologically relevant pH of ThDP-dependent enzymes around neutrality does not seem to be suitable for the formation of such reactive chemical species. Herein, we investigate the general mechanism of activation of the ThDP cofactor in human transketolase (TKT), by means of electronic structure methods. We show that in the case of the human TKT, the carbene species is accessible through a pKa shift induced by the electrostatics of a neighboring histidine residue (H110), whose protonation state change modulates the pKa of ThDP and suppresses the latter by more than 6 pH units. Our findings highlight that ThDP enzymes activate the cofactor beyond simple geometric constraints and the canonical glutamate. Such observations in nature can pave the way for the design of biomimetic carbene catalysts and the engineering of tailored enzymatic carbenes.
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Affiliation(s)
- Jon Uranga
- Institute
of Physical Chemistry, Georg-August Universität
Göttingen, Tammannstraße 6, 37077 Göttingen, Germany
| | - Fabian Rabe von Pappenheim
- Department
of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August Universität Göttingen, Julia-Lermonotowa-Weg 3, D-37077 Göttingen, Germany
| | - Kai Tittmann
- Department
of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August Universität Göttingen, Julia-Lermonotowa-Weg 3, D-37077 Göttingen, Germany
- Department
of Physical Biochemistry, Max-Planck-Institute
for Multidisciplinary Natural Sciences, Am Faßberg 11, D-37077 Göttingen, Germany
| | - Ricardo A. Mata
- Institute
of Physical Chemistry, Georg-August Universität
Göttingen, Tammannstraße 6, 37077 Göttingen, Germany
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3
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Delfau L, Assani N, Nichilo S, Pecaut J, Philouze C, Broggi J, Martin D, Tomás-Mendivil E. On the Redox Properties of the Dimers of Thiazol-2-ylidenes That Are Relevant for Radical Catalysis. ACS ORGANIC & INORGANIC AU 2023; 3:136-142. [PMID: 37303499 PMCID: PMC10251502 DOI: 10.1021/acsorginorgau.3c00008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/23/2023] [Accepted: 03/23/2023] [Indexed: 06/13/2023]
Abstract
We report the isolation and study of dimers stemming from popular thiazol-2-ylidene organocatalysts. The model featuring 2,6-di(isopropyl)phenyl (Dipp) N-substituents was found to be a stronger reducing agent (Eox = -0.8 V vs SCE) than bis(thiazol-2-ylidenes) previously studied in the literature. In addition, a remarkable potential gap between the first and second oxidation of the dimer also allows for the isolation of the corresponding air-persistent radical cation. The latter is an unexpected efficient promoter of the radical transformation of α-bromoamides into oxindoles.
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Affiliation(s)
| | - Nadhrata Assani
- Aix
Marseille Univ., CNRS, Institut de Chimie Radicalaire - UMR 7273,
Faculté de Pharmacie, 13005 Marseille, France
| | | | - Jacques Pecaut
- Univ.
Grenoble Alpes, CEA, CNRS, INAC-SyMMES, UMR 5819 38000 Grenoble, France
| | | | - Julie Broggi
- Aix
Marseille Univ., CNRS, Institut de Chimie Radicalaire - UMR 7273,
Faculté de Pharmacie, 13005 Marseille, France
| | - David Martin
- Univ.
Grenoble Alpes, CNRS, DCM, 38000 Grenoble, France
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4
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Huang J, Quest A, Cruz-Morales P, Deng K, Pereira JH, Van Cura D, Kakumanu R, Baidoo EEK, Dan Q, Chen Y, Petzold CJ, Northen TR, Adams PD, Clark DS, Balskus EP, Hartwig JF, Mukhopadhyay A, Keasling JD. Complete integration of carbene-transfer chemistry into biosynthesis. Nature 2023; 617:403-408. [PMID: 37138074 PMCID: PMC11334723 DOI: 10.1038/s41586-023-06027-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 03/28/2023] [Indexed: 05/05/2023]
Abstract
Biosynthesis is an environmentally benign and renewable approach that can be used to produce a broad range of natural and, in some cases, new-to-nature products. However, biology lacks many of the reactions that are available to synthetic chemists, resulting in a narrower scope of accessible products when using biosynthesis rather than synthetic chemistry. A prime example of such chemistry is carbene-transfer reactions1. Although it was recently shown that carbene-transfer reactions can be performed in a cell and used for biosynthesis2,3, carbene donors and unnatural cofactors needed to be added exogenously and transported into cells to effect the desired reactions, precluding cost-effective scale-up of the biosynthesis process with these reactions. Here we report the access to a diazo ester carbene precursor by cellular metabolism and a microbial platform for introducing unnatural carbene-transfer reactions into biosynthesis. The α-diazoester azaserine was produced by expressing a biosynthetic gene cluster in Streptomyces albus. The intracellularly produced azaserine was used as a carbene donor to cyclopropanate another intracellularly produced molecule-styrene. The reaction was catalysed by engineered P450 mutants containing a native cofactor with excellent diastereoselectivity and a moderate yield. Our study establishes a scalable, microbial platform for conducting intracellular abiological carbene-transfer reactions to functionalize a range of natural and new-to-nature products and expands the scope of organic products that can be produced by cellular metabolism.
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Affiliation(s)
- Jing Huang
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA
| | - Andrew Quest
- Department of Chemistry, University of California, Berkeley, CA, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Pablo Cruz-Morales
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Kai Deng
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
- Department of Biomaterials and Biomanufacturing, Sandia National Laboratories, Livermore, CA, USA
| | - Jose Henrique Pereira
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Devon Van Cura
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Ramu Kakumanu
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
| | - Edward E K Baidoo
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
| | - Qingyun Dan
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
| | - Yan Chen
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
| | - Christopher J Petzold
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
| | - Trent R Northen
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Paul D Adams
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department of Bioengineering, University of California, Berkeley, CA, USA
| | - Douglas S Clark
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA.
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
| | - John F Hartwig
- Department of Chemistry, University of California, Berkeley, CA, USA.
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Aindrila Mukhopadhyay
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA.
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Jay D Keasling
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
- Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA, USA.
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, USA.
- Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark.
- Department of Bioengineering, University of California, Berkeley, CA, USA.
- Synthetic Biochemistry Center, Institute for Synthetic Biology, Shenzhen Institutes for Advanced Technologies, Shenzhen, China.
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5
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Abstract
Carbenes are highly reactive compounds with unique value to synthetic chemistry. However, a small number of natural enzymes have been shown to utilize carbene chemistry, and artificial enzymes engineered with directed evolution required transition metal ions to stabilize the carbene intermediates. To facilitate the design of broader classes of enzymes that can take advantage of the rich carbene chemistry, it is thus important to better understand how to stabilize carbene species in enzyme active sites without metal ions. Motivated by our recent studies of the anaerobic ergothioneine biosynthesis enzyme EanB, we examine carbene-protein interaction with both cluster models and QM/MM simulations. The cluster calculations find that an N-heterocyclic carbene interacts strongly with polar and positively charged protein motifs. In particular, the interaction between a guanidinium group and carbene is as strong as ∼30 kcal/mol, making arginine a great choice for the preferential stabilization of carbenes. We also compare the WT EanB and its mutant in which the key tyrosine was replaced by a non-natural analogue (F2Tyr) using DFTB3/MM simulations. The calculations suggest that the carbene intermediate in the F2Tyr mutant is more stable than that in the WT enzyme by ∼3.5 kcal/mol, due to active site rearrangements that enable a nearby arginine to better stabilize the carbene in the mutant. Overall, the current work lays the foundation for the pursuit of enzyme designs that can take advantage of the unique chemistry offered by carbenes without the requirement of metal ions.
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Affiliation(s)
- Rui Lai
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian 116023, China
| | - Qiang Cui
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, United States
- Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, Massachusetts 02215, United States
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6
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Prajapati S, Rabe von Pappenheim F, Tittmann K. Frontiers in the enzymology of thiamin diphosphate-dependent enzymes. Curr Opin Struct Biol 2022; 76:102441. [PMID: 35988322 DOI: 10.1016/j.sbi.2022.102441] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/07/2022] [Accepted: 07/11/2022] [Indexed: 11/25/2022]
Abstract
Enzymes that use thiamin diphosphate (ThDP), the biologically active derivative of vitamin B1, as a cofactor play important roles in cellular metabolism in all domains of life. The analysis of ThDP enzymes in the past decades have provided a general framework for our understanding of enzyme catalysis of this protein family. In this review, we will discuss recent advances in the field that include the observation of "unusual" reactions and reaction intermediates that highlight the chemical versatility of the thiamin cofactor. Further topics cover the structural basis of cooperativity of ThDP enzymes, novel insights into the mechanism and structure of selected enzymes, and the discovery of "superassemblies" as reported, for example, acetohydroxy acid synthase. Finally, we summarize recent findings in the structural organisation and mode of action of 2-keto acid dehydrogenase multienzyme complexes and discuss future directions of this exciting research field.
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Affiliation(s)
- Sabin Prajapati
- Department of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany.
| | - Fabian Rabe von Pappenheim
- Department of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany.
| | - Kai Tittmann
- Department of Molecular Enzymology, Göttingen Center of Molecular Biosciences, Georg-August University Göttingen, Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany; Max-Planck-Institute for Multidisciplinary Sciences, Am Fassberg 11, D-37077 Göttingen, Germany.
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7
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Lechner H, Oberdorfer G. Derivatives of Natural Organocatalytic Cofactors and Artificial Organocatalytic Cofactors as Catalysts in Enzymes. Chembiochem 2022; 23:e202100599. [PMID: 35302276 PMCID: PMC9401024 DOI: 10.1002/cbic.202100599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 03/14/2022] [Indexed: 11/11/2022]
Abstract
Catalytically active non-metal cofactors in enzymes carry out a variety of different reactions. The efforts to develop derivatives of naturally occurring cofactors such as flavins or pyridoxal phosphate and the advances to design new, non-natural cofactors are reviewed here. We report the status quo for enzymes harboring organocatalysts as derivatives of natural cofactors or as artificial ones and their application in the asymmetric synthesis of various compounds.
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Affiliation(s)
- Horst Lechner
- Graz University of TechnologyInstitute of BiochemistryPetersgasse 10–12/II8010GrazAustria
| | - Gustav Oberdorfer
- Graz University of TechnologyInstitute of BiochemistryPetersgasse 10–12/II8010GrazAustria
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8
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Cordell GA, Lamahewage SNS. Ergothioneine, Ovothiol A, and Selenoneine-Histidine-Derived, Biologically Significant, Trace Global Alkaloids. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27092673. [PMID: 35566030 PMCID: PMC9103826 DOI: 10.3390/molecules27092673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/15/2022] [Accepted: 04/16/2022] [Indexed: 11/16/2022]
Abstract
The history, chemistry, biology, and biosynthesis of the globally occurring histidine-derived alkaloids ergothioneine (10), ovothiol A (11), and selenoneine (12) are reviewed comparatively and their significance to human well-being is discussed.
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Affiliation(s)
- Geoffrey A. Cordell
- Natural Products Inc., Evanston, IL 60202, USA
- Department of Pharmaceutics, College of Pharmacy, University of Florida, Gainesville, FL 32610, USA
- Correspondence:
| | - Sujeewa N. S. Lamahewage
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA;
- Department of Chemistry, University of Ruhuna, Matara 81000, Sri Lanka
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9
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Abstract
Biocatalysis has an enormous impact on chemical synthesis. The waves in which biocatalysis has developed, and in doing so changed our perception of what organic chemistry is, were reviewed 20 and 10 years ago. Here we review the consequences of these waves of development. Nowadays, hydrolases are widely used on an industrial scale for the benign synthesis of commodity and bulk chemicals and are fully developed. In addition, further enzyme classes are gaining ever increasing interest. Particularly, enzymes catalysing selective C-C-bond formation reactions and enzymes catalysing selective oxidation and reduction reactions are solving long-standing synthetic challenges in organic chemistry. Combined efforts from molecular biology, systems biology, organic chemistry and chemical engineering will establish a whole new toolbox for chemistry. Recent developments are critically reviewed.
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Affiliation(s)
- Ulf Hanefeld
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, The Netherlands.
| | - Frank Hollmann
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, The Netherlands.
| | - Caroline E Paul
- Biocatalysis, Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, The Netherlands.
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10
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Nauton L, Hecquet L, Théry V. QM/MM Study of Human Transketolase: Thiamine Diphosphate Activation Mechanism and Complete Catalytic Cycle. J Chem Inf Model 2021; 61:3502-3515. [PMID: 34161071 DOI: 10.1021/acs.jcim.1c00190] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A computational model for human transketolase was proposed, showing that thiamine diphosphate activation was based on His110 in place of His481 reported in yeast transketolase. In addition, a complete catalytic reaction pathway was investigated using d-xylulose-5-phosphate and d-ribose-5-phosphate as substrates, showing at every step a perfect superimposition of our model with high-resolution crystallographic structures 3MOS, 4KXV, and 4KXX. This study shows that H2N4' of the active thiamine diphosphate "V form" no longer has a self-activating role but allows self-stabilization of the cofactor and of the Breslow intermediate. These advances in our knowledge of the human transketolase mechanism offer interesting prospects for the design of new drugs, this enzyme being involved in several diseases, and for a better understanding of the reactions catalyzed by transketolases from other sources.
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Affiliation(s)
- Lionel Nauton
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, ICCF, F-63000 Clermont-Ferrand, France
| | - Laurence Hecquet
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, ICCF, F-63000 Clermont-Ferrand, France
| | - Vincent Théry
- Université Clermont Auvergne, CNRS, Clermont Auvergne INP, ICCF, F-63000 Clermont-Ferrand, France
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11
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Cheng R, Lai R, Peng C, Lopez J, Li Z, Naowarojna N, Li K, Wong C, Lee N, Whelan SA, Qiao L, Grinstaff MW, Wang J, Cui Q, Liu P. Implications for an imidazol-2-yl carbene intermediate in the rhodanase-catalyzed C-S bond formation reaction of anaerobic ergothioneine biosynthesis. ACS Catal 2021; 11:3319-3334. [PMID: 34745712 DOI: 10.1021/acscatal.0c04886] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In the anaerobic ergothioneine biosynthetic pathway, a rhodanese domain containing enzyme (EanB) activates tne hercynine's sp2 ε-C-H Dona ana replaces it with a C-S bond to produce ergothioneine. The key intermediate for this trans-sulfuration reaction is the Cys412 persulfide. Substitution of the EanB-Cys412 persulfide with a Cys412 perselenide does not yield the selenium analog of ergothioneine, selenoneine. However, in deuterated buffer, the perselenide-modified EanB catalyzes the deuterium exchange between hercynine's sp2 ε-C-H bond and D2O. Results from QM/MM calculations suggest that the reaction involves a carbene intermediate and that Tyr353 plays a key role. We hypothesize that modulating the pKa of Tyr353 will affect the deuterium-exchange rate. Indeed, the 3,5-difluoro tyrosine containing EanB catalyzes the deuterium exchange reaction with k ex of ~10-fold greater than the wild-type EanB (EanBWT). With regards to potential mechanisms, these results support the involvement of a carbene intermediate in EanB-catalysis, rendering EanB as one of the few carbene-intermediate involving enzymatic systems.
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Affiliation(s)
- Ronghai Cheng
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Rui Lai
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Chao Peng
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 201210, China
| | - Juan Lopez
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Zhihong Li
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 201210, China
| | - Nathchar Naowarojna
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Kelin Li
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Christina Wong
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Norman Lee
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Stephen A. Whelan
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Lu Qiao
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Mark W. Grinstaff
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Jiangyun Wang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People’s Republic of China
| | - Qiang Cui
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
| | - Pinghua Liu
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, USA
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12
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Medina FE, Prejanò M. Water Molecules Allow the Intramolecular Activation of the Thiamine Di-Phosphate Cofactor in Human Transketolase: Mechanistic Insights into a Famous Proposal. ACS Catal 2021. [DOI: 10.1021/acscatal.0c05414] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Fabiola E. Medina
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Autopista Concepción-Talcahuano, Talcahuano 7100, Chile
| | - Mario Prejanò
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-10691, Sweden
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13
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Planchestainer M, McMaster J, Schulz C, Paradisi F, Albrecht M. Carbene-Induced Rescue of Catalytic Activity in Deactivated Nitrite Reductase Mutant. Chemistry 2020; 26:15206-15211. [PMID: 32543723 DOI: 10.1002/chem.202002444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Indexed: 11/10/2022]
Abstract
The role of His145 in the T1 copper center of nitrite reductase (NiR) is pivotal for the activity of the enzyme. Mutation to a glycine at this position enables the reconstitution of the T1 center by the addition of imidazole as exogenous ligands, however the catalytic activity is only marginally rescued. Here, we demonstrate that the uptake of 1,3-dimethylimidazolylidene as N-heterocyclic carbene (NHC) by the H145G NiR mutant instead of imidazole yields a significantly more active catalyst, suggesting a beneficial role of such C-bonding. Spectroscopic analyses of the formed H145G≈NHC variant as well as an analogue without the catalytic T2 copper center reveal no significant alteration of the T1 site compared to the wild type or the variant containing imidazole as exogenous N-bound surrogate of H145. However, the presence of the carbene doubles the catalytic activity of the mutant compared to the imidazole variant. This enhanced activity has been attributed to a faster electron transfer to the T1 center in the NHC variant and a concomitant change of the rate-limiting step.
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Affiliation(s)
- Matteo Planchestainer
- University of Bern, Department of Chemistry & Biochemistry, Freiestr. 3, 3012, Bern, Switzerland.,University of Nottingham, School of Chemistry, University Park, Nottingham, NG7 2RD, UK
| | - Jonathan McMaster
- University of Nottingham, School of Chemistry, University Park, Nottingham, NG7 2RD, UK
| | - Christine Schulz
- Max-Planck Institut für Kohlenforschung, Department of Molecular Theory and Spectroscopy, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Francesca Paradisi
- University of Bern, Department of Chemistry & Biochemistry, Freiestr. 3, 3012, Bern, Switzerland.,University of Nottingham, School of Chemistry, University Park, Nottingham, NG7 2RD, UK
| | - Martin Albrecht
- University of Bern, Department of Chemistry & Biochemistry, Freiestr. 3, 3012, Bern, Switzerland
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14
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Kinney ZJ, Rheingold AL, Protasiewicz JD. Preferential N-H⋯:C[double bond splayed right] hydrogen bonding involving ditopic NH-containing systems and N-heterocyclic carbenes. RSC Adv 2020; 10:42164-42171. [PMID: 35516763 PMCID: PMC9057831 DOI: 10.1039/d0ra08490e] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/05/2020] [Indexed: 11/21/2022] Open
Abstract
Hydrogen bonding plays a critical role in maintaining order and structure in complex biological and synthetic systems. N-heterocyclic carbenes (NHCs) represent one of the most versatile tools in the synthetic chemistry toolbox, yet their potential as neutral carbon hydrogen bond acceptors remains underexplored. This report investigates this capability in a strategic manner, wherein carbene-based hydrogen bonding can be assessed by use of ditopic NH-containing molecules. N-H bonds are unique as there are three established reaction modes with carbenes: non-traditional hydrogen bonding adducts (X-H⋯:C[double bond splayed right]), salts arising from proton transfer ([H-C[double bond splayed right]]+[X]-), or amines from insertion of the carbene into the N-H bond. Yet, there are no established rules to predict product distributions or the strength of these associations. Here we seek to correlate the hydrogen bond strength of symmetric and asymmetric ditopic secondary amines with 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr, a representative NHC). In symmetric and asymmetric ditopic amine adducts both the solid-state (hydrogen bond lengths, NHC interior angles) and solution-state (1H Δδ of NH signals, 13C signals of carbenic carbon) can be related to the pK a of the parent amine.
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Affiliation(s)
- Zacharias J Kinney
- Department of Chemistry, Case Western Reserve University Cleveland Ohio 44106 USA
| | - Arnold L Rheingold
- Department of Chemistry and Biochemistry, University of California La Jolla San Diego California 92093 USA
| | - John D Protasiewicz
- Department of Chemistry, Case Western Reserve University Cleveland Ohio 44106 USA
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15
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Structural basis for antibiotic action of the B 1 antivitamin 2'-methoxy-thiamine. Nat Chem Biol 2020; 16:1237-1245. [PMID: 32839604 DOI: 10.1038/s41589-020-0628-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 07/17/2020] [Indexed: 02/07/2023]
Abstract
The natural antivitamin 2'-methoxy-thiamine (MTh) is implicated in the suppression of microbial growth. However, its mode of action and enzyme-selective inhibition mechanism have remained elusive. Intriguingly, MTh inhibits some thiamine diphosphate (ThDP) enzymes, while being coenzymatically active in others. Here we report the strong inhibition of Escherichia coli transketolase activity by MTh and unravel its mode of action and the structural basis thereof. The unique 2'-methoxy group of MTh diphosphate (MThDP) clashes with a canonical glutamate required for cofactor activation in ThDP-dependent enzymes. This glutamate is forced into a stable, anticatalytic low-barrier hydrogen bond with a neighboring glutamate, disrupting cofactor activation. Molecular dynamics simulations of transketolases and other ThDP enzymes identify active-site flexibility and the topology of the cofactor-binding locale as key determinants for enzyme-selective inhibition. Human enzymes either retain enzymatic activity with MThDP or preferentially bind authentic ThDP over MThDP, while core bacterial metabolic enzymes are inhibited, demonstrating therapeutic potential.
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16
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Cheng R, Wu L, Lai R, Peng C, Naowarojna N, Hu W, Li X, Whelan SA, Lee N, Lopez J, Zhao C, Yong Y, Xue J, Jiang X, Grinstaff MW, Deng Z, Chen J, Cui Q, Zhou J, Liu P. Single-step Replacement of an Unreactive C-H Bond by a C-S Bond Using Polysulfide as the Direct Sulfur Source in Anaerobic Ergothioneine Biosynthesis. ACS Catal 2020; 10:8981-8994. [PMID: 34306804 DOI: 10.1021/acscatal.0c01809] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Ergothioneine, a natural longevity vitamin and antioxidant, is a thiol-histidine derivative. Recently, two types of biosynthetic pathways were reported. In the aerobic ergothioneine biosynthesis, a non-heme iron enzyme incorporates a sulfoxide to an sp2 C-H bond in trimethyl-histidine (hercynine) through oxidation reactions. In contrast, in the anaerobic ergothioneine biosynthetic pathway in a green sulfur bacterium, Chlorobium limicola, a rhodanese domain containing protein (EanB) directly replaces this unreactive hercynine C-H bond with a C-S bond. Herein, we demonstrate that polysulfide (HSSnSR) is the direct sulfur-source in EanB-catalysis. After identifying EanB's substrates, X-ray crystallography of several intermediate states along with mass spectrometry results provide additional mechanistic details for this reaction. Further, quantum mechanics/molecular mechanics (QM/MM) calculations reveal that protonation of Nπ of hercynine by Tyr353 with the assistance of Thr414 is a key activation step for the hercynine sp2 C-H bond in this trans-sulfuration reaction.
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Affiliation(s)
- Ronghai Cheng
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Lian Wu
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Shanghai 200032, China
- College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rui Lai
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Chao Peng
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 201210, China
| | - Nathchar Naowarojna
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Weiyao Hu
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xinhao Li
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Stephen A. Whelan
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Norman Lee
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Juan Lopez
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Changming Zhao
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
- Key Laboratory of Combinatory Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Hubei 430072, China
| | - Youhua Yong
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
| | - Jiahui Xue
- Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Xuefeng Jiang
- Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China
| | - Mark W. Grinstaff
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, United States
| | - Zixin Deng
- Key Laboratory of Combinatory Biosynthesis and Drug Discovery (Wuhan University), Ministry of Education, School of Pharmaceutical Sciences, Wuhan University, Hubei 430072, China
| | - Jiesheng Chen
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Qiang Cui
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
| | - Jiahai Zhou
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
| | - Pinghua Liu
- Department of Chemistry, Boston University, Boston, Massachusetts 02215, United States
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17
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Gehrke S, Hollóczki O. N-Heterocyclic Carbene Organocatalysis: With or Without Carbenes? Chemistry 2020; 26:10140-10151. [PMID: 32608090 PMCID: PMC7496998 DOI: 10.1002/chem.202002656] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/26/2020] [Indexed: 11/18/2022]
Abstract
In this work the mechanism of the aldehyde umpolung reactions, catalyzed by azolium cations in the presence of bases, was studied through computational methods. Next to the mechanism established by Breslow in the 1950s that takes effect through the formation of a free carbene, we have suggested that these processes can follow a concerted asynchronous path, in which the azolium cation directly reacts with the substrate, avoiding the formation of the carbene intermediate. We hereby show that substituting the azolium cation, and varying the base or the substrate do not affect the preference for the concerted reaction mechanism. The concerted path was found to exhibit low barriers also for the reactions of thiamine with model substrates, showing that this path might have biological relevance. The dominance of the concerted mechanism can be explained through the specific structure of the key transition state, avoiding the liberation of the highly reactive, and thus unstable carbene lone pair, whereas activating the substrate through hydrogen-bonding interactions. Polar and hydrogen-bonding solvents, as well as the presence of the counterions of the azolium salts facilitate the reaction through carbenes, bringing the barriers of the two reaction mechanisms closer, in many cases making the concerted path less favorable. Thus, our data show that by choosing the exact components in a reaction, the mechanism can be switched to occur with or without carbenes.
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Affiliation(s)
- Sascha Gehrke
- Mulliken Center for Theoretical ChemistryUniversity of BonnBeringstr. 4+653115BonnGermany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical ChemistryUniversity of BonnBeringstr. 4+653115BonnGermany
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18
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Hollóczki O. The Mechanism of N-Heterocyclic Carbene Organocatalysis through a Magnifying Glass. Chemistry 2020; 26:4885-4894. [PMID: 31797448 PMCID: PMC7187225 DOI: 10.1002/chem.201903021] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Indexed: 11/11/2022]
Abstract
The term "N-Heterocyclic carbene organocatalysis" is often invoked in organic synthesis for reactions that are catalyzed by different azolium salts in the presence of bases. Although the mechanism of these reactions is considered today evident, a closer look into the details that have been collected throughout the last century reveals that there are many open questions and even contradictions in the field. Emerging new theoretical and experimental results offer solutions to these problems, because they show that through considering alternative reaction mechanisms a more consistent picture on the catalytic process can be obtained. These novel perspectives will be able to extend the scope of the reactions that we call today N-heterocyclic carbene organocatalysis.
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Affiliation(s)
- Oldamur Hollóczki
- Mulliken Center for Theoretical ChemistryUniversity of BonnBeringstrasse 4+653115BonnGermany
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19
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20
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Manna D, Lo R, Hobza P. Spin modification of iron(ii) complexes via covalent (dative) and dispersion guided non-covalent bonding with N-heterocyclic carbenes: DFT, DLPNO-CCSD(T) and MCSCF studies. Dalton Trans 2020; 49:164-170. [DOI: 10.1039/c9dt04334a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spin crossover from high spin Fe(ii)-phthalocyanine to low or intermediate spin via either dative covalent or non-covalent interaction by just varying the substituent using the same core ligand.
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Affiliation(s)
- Debashree Manna
- Institute of Organic Chemistry and Biochemistry
- Academy of Sciences of the Czech Republic
- 16610 Prague 6
- Czech Republic
- Regional Centre of Advanced Technologies and Materials
| | - Rabindranath Lo
- Institute of Organic Chemistry and Biochemistry
- Academy of Sciences of the Czech Republic
- 16610 Prague 6
- Czech Republic
- Regional Centre of Advanced Technologies and Materials
| | - Pavel Hobza
- Institute of Organic Chemistry and Biochemistry
- Academy of Sciences of the Czech Republic
- 16610 Prague 6
- Czech Republic
- Regional Centre of Advanced Technologies and Materials
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21
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Dai S, Funk LM, von Pappenheim FR, Sautner V, Paulikat M, Schröder B, Uranga J, Mata RA, Tittmann K. Low-barrier hydrogen bonds in enzyme cooperativity. Nature 2019; 573:609-613. [PMID: 31534226 DOI: 10.1038/s41586-019-1581-9] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/12/2019] [Indexed: 11/09/2022]
Abstract
The underlying molecular mechanisms of cooperativity and allosteric regulation are well understood for many proteins, with haemoglobin and aspartate transcarbamoylase serving as prototypical examples1,2. The binding of effectors typically causes a structural transition of the protein that is propagated through signalling pathways to remote sites and involves marked changes on the tertiary and sometimes even the quaternary level1-5. However, the origin of these signals and the molecular mechanism of long-range signalling at an atomic level remain unclear5-8. The different spatial scales and timescales in signalling pathways render experimental observation challenging; in particular, the positions and movement of mobile protons cannot be visualized by current methods of structural analysis. Here we report the experimental observation of fluctuating low-barrier hydrogen bonds as switching elements in cooperativity pathways of multimeric enzymes. We have observed these low-barrier hydrogen bonds in ultra-high-resolution X-ray crystallographic structures of two multimeric enzymes, and have validated their assignment using computational calculations. Catalytic events at the active sites switch between low-barrier hydrogen bonds and ordinary hydrogen bonds in a circuit that consists of acidic side chains and water molecules, transmitting a signal through the collective repositioning of protons by behaving as an atomistic Newton's cradle. The resulting communication synchronizes catalysis in the oligomer. Our studies provide several lines of evidence and a working model for not only the existence of low-barrier hydrogen bonds in proteins, but also a connection to enzyme cooperativity. This finding suggests new principles of drug and enzyme design, in which sequences of residues can be purposefully included to enable long-range communication and thus the regulation of engineered biomolecules.
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Affiliation(s)
- Shaobo Dai
- Department of Molecular Enzymology, Göttingen Centre for Molecular Biosciences and Albrecht-von-Haller Institute, Georg-August University Göttingen, Göttingen, Germany.,Department of Structural Dynamics, Max-Planck-Institute for Biophysical Chemistry Göttingen, Göttingen, Germany
| | - Lisa-Marie Funk
- Department of Molecular Enzymology, Göttingen Centre for Molecular Biosciences and Albrecht-von-Haller Institute, Georg-August University Göttingen, Göttingen, Germany.,Department of Structural Dynamics, Max-Planck-Institute for Biophysical Chemistry Göttingen, Göttingen, Germany
| | - Fabian Rabe von Pappenheim
- Department of Molecular Enzymology, Göttingen Centre for Molecular Biosciences and Albrecht-von-Haller Institute, Georg-August University Göttingen, Göttingen, Germany.,Department of Structural Dynamics, Max-Planck-Institute for Biophysical Chemistry Göttingen, Göttingen, Germany
| | - Viktor Sautner
- Department of Molecular Enzymology, Göttingen Centre for Molecular Biosciences and Albrecht-von-Haller Institute, Georg-August University Göttingen, Göttingen, Germany.,Department of Structural Dynamics, Max-Planck-Institute for Biophysical Chemistry Göttingen, Göttingen, Germany
| | - Mirko Paulikat
- Institute of Physical Chemistry, Georg-August University Göttingen, Göttingen, Germany
| | - Benjamin Schröder
- Institute of Physical Chemistry, Georg-August University Göttingen, Göttingen, Germany
| | - Jon Uranga
- Institute of Physical Chemistry, Georg-August University Göttingen, Göttingen, Germany
| | - Ricardo A Mata
- Institute of Physical Chemistry, Georg-August University Göttingen, Göttingen, Germany.
| | - Kai Tittmann
- Department of Molecular Enzymology, Göttingen Centre for Molecular Biosciences and Albrecht-von-Haller Institute, Georg-August University Göttingen, Göttingen, Germany. .,Department of Structural Dynamics, Max-Planck-Institute for Biophysical Chemistry Göttingen, Göttingen, Germany.
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22
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Desmons S, Fauré R, Bontemps S. Formaldehyde as a Promising C1 Source: The Instrumental Role of Biocatalysis for Stereocontrolled Reactions. ACS Catal 2019. [DOI: 10.1021/acscatal.9b03128] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Sarah Desmons
- LCC-CNRS, Université de Toulouse, CNRS, Toulouse, France
- TBI, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
| | - Régis Fauré
- TBI, Université de Toulouse, CNRS, INRA, INSA, Toulouse, France
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23
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24
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Leisinger F, Burn R, Meury M, Lukat P, Seebeck FP. Structural and Mechanistic Basis for Anaerobic Ergothioneine Biosynthesis. J Am Chem Soc 2019; 141:6906-6914. [DOI: 10.1021/jacs.8b12596] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Florian Leisinger
- Department for Chemistry, University of Basel, Mattenstrasse 24a, BPR 1002, 4056, Basel, Switzerland
| | - Reto Burn
- Department for Chemistry, University of Basel, Mattenstrasse 24a, BPR 1002, 4056, Basel, Switzerland
| | - Marcel Meury
- Department for Chemistry, University of Basel, Mattenstrasse 24a, BPR 1002, 4056, Basel, Switzerland
| | - Peer Lukat
- Structure and Function of Proteins, Helmholtz Centre for Infection Research, Inhoffenstr. 7, 38124, Braunschweig, Germany
| | - Florian P. Seebeck
- Department for Chemistry, University of Basel, Mattenstrasse 24a, BPR 1002, 4056, Basel, Switzerland
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25
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Hoffbauer MR, Comanescu CC, Iluc VM. Reactivity of a Pd(II) carbene towards 2,6-dimesitylphenyldiazomethane and 2,6-dimesitylphenylazide. Polyhedron 2019. [DOI: 10.1016/j.poly.2018.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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26
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Hsu N, Wang Y, Lin K, Chang C, Ke S, Lyu S, Hsu L, Li Y, Chen S, Wang K, Li T. Evidence of Diradicals Involved in the Yeast Transketolase Catalyzed Keto-Transferring Reactions. Chembiochem 2018; 19:2395-2402. [PMID: 30155962 PMCID: PMC6282555 DOI: 10.1002/cbic.201800378] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Indexed: 11/12/2022]
Abstract
Transketolase (TK) catalyzes a reversible transfer of a two-carbon (C2 ) unit between phosphoketose donors and phosphoaldose acceptors, for which the group-transfer reaction that follows a one- or two-electron mechanism and the force that breaks the C2"-C3" bond of the ketose donors remain unresolved. Herein, we report ultrahigh-resolution crystal structures of a TK (TKps) from Pichia stipitis in previously undiscovered intermediate states and support a diradical mechanism for a reversible group-transfer reaction. In conjunction with MS, NMR spectroscopy, EPR and computational analyses, it is concluded that the enzyme-catalyzed non-Kekulé diradical cofactor brings about the C2"-C3" bond cleavage/formation for the C2 -unit transfer reaction, for which suppression of activation energy and activation and destabilization of enzymatic intermediates are facilitated.
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Affiliation(s)
- Ning‐Shian Hsu
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
- Institute of Biochemistry and Molecular BiologyNational Yang-Ming UniversityTaipei112Taiwan
| | - Yung‐Lin Wang
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Kuan‐Hung Lin
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
- Institute of Biochemistry and Molecular BiologyNational Yang-Ming UniversityTaipei112Taiwan
| | - Chi‐Fon Chang
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Shyue‐Chu Ke
- Department of PhysicsNational Dong Hwa UniversityHualien974Taiwan
| | - Syue‐Yi Lyu
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Li‐Jen Hsu
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | - Yi‐Shan Li
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
| | | | | | - Tsung‐Lin Li
- Genomics Research CenterAcademia SinicaTaipei115Taiwan
- Biotechnology CenterNational Chung Hsing UniversityTaichung City402Taiwan
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27
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Lewis RD, Garcia-Borràs M, Chalkley MJ, Buller AR, Houk KN, Kan SBJ, Arnold FH. Catalytic iron-carbene intermediate revealed in a cytochrome c carbene transferase. Proc Natl Acad Sci U S A 2018; 115:7308-7313. [PMID: 29946033 PMCID: PMC6048479 DOI: 10.1073/pnas.1807027115] [Citation(s) in RCA: 84] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recently, heme proteins have been discovered and engineered by directed evolution to catalyze chemical transformations that are biochemically unprecedented. Many of these nonnatural enzyme-catalyzed reactions are assumed to proceed through a catalytic iron porphyrin carbene (IPC) intermediate, although this intermediate has never been observed in a protein. Using crystallographic, spectroscopic, and computational methods, we have captured and studied a catalytic IPC intermediate in the active site of an enzyme derived from thermostable Rhodothermus marinus (Rma) cytochrome c High-resolution crystal structures and computational methods reveal how directed evolution created an active site for carbene transfer in an electron transfer protein and how the laboratory-evolved enzyme achieves perfect carbene transfer stereoselectivity by holding the catalytic IPC in a single orientation. We also discovered that the IPC in Rma cytochrome c has a singlet ground electronic state and that the protein environment uses geometrical constraints and noncovalent interactions to influence different IPC electronic states. This information helps us to understand the impressive reactivity and selectivity of carbene transfer enzymes and offers insights that will guide and inspire future engineering efforts.
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Affiliation(s)
- Russell D Lewis
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena, CA 91125
| | - Marc Garcia-Borràs
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095
| | - Matthew J Chalkley
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Andrew R Buller
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - K N Houk
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095;
| | - S B Jennifer Kan
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Frances H Arnold
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena, CA 91125;
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
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28
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Qin M, Song H, Dai X, Chan C, Chan W, Guo Z. Single‐Turnover Kinetics Reveal a Distinct Mode of Thiamine Diphosphate‐Dependent Catalysis in Vitamin K Biosynthesis. Chembiochem 2018; 19:1514-1522. [DOI: 10.1002/cbic.201800143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Indexed: 01/09/2023]
Affiliation(s)
- Mingming Qin
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Haigang Song
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
- Present address: Division of Structural BiologyWellcome Trust Centre of Human GenomicsUniversity of Oxford Roosevelt Drive Oxford OX3 7BN UK
| | - Xin Dai
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Chi‐Kong Chan
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
- Environmental Science ProgramThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Wan Chan
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
- Environmental Science ProgramThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
| | - Zhihong Guo
- Department of ChemistryThe Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong
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29
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Hsu NS, Wang YL, Lin KH, Chang CF, Lyu SY, Hsu LJ, Liu YC, Chang CY, Wu CJ, Li TL. The Mesomeric Effect of Thiazolium on non-Kekulé Diradicals in Pichia stipitis
Transketolase. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201709799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Ning-Shian Hsu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
- Institute of Biochemistry and Molecular Biology; National Yang-Ming University; Taipei 112 Taiwan
| | - Yung-Lin Wang
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Kuan-Hung Lin
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
- Institute of Biochemistry and Molecular Biology; National Yang-Ming University; Taipei 112 Taiwan
| | - Chi-Fon Chang
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Syue-Yi Lyu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Li-Jen Hsu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Yu-Chen Liu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Chin-Yuan Chang
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Chang-Jer Wu
- Department of Food Science; National (Taiwan) Ocean University; Keelung 202 Taiwan
| | - Tsung-Lin Li
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
- Biotechnology Center; National Chung Hsing University; Taichung City 402 Taiwan
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30
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Hsu NS, Wang YL, Lin KH, Chang CF, Lyu SY, Hsu LJ, Liu YC, Chang CY, Wu CJ, Li TL. The Mesomeric Effect of Thiazolium on non-Kekulé Diradicals in Pichia stipitis
Transketolase. Angew Chem Int Ed Engl 2018; 57:1802-1807. [DOI: 10.1002/anie.201709799] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 11/23/2017] [Indexed: 11/07/2022]
Affiliation(s)
- Ning-Shian Hsu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
- Institute of Biochemistry and Molecular Biology; National Yang-Ming University; Taipei 112 Taiwan
| | - Yung-Lin Wang
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Kuan-Hung Lin
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
- Institute of Biochemistry and Molecular Biology; National Yang-Ming University; Taipei 112 Taiwan
| | - Chi-Fon Chang
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Syue-Yi Lyu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Li-Jen Hsu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Yu-Chen Liu
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Chin-Yuan Chang
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
| | - Chang-Jer Wu
- Department of Food Science; National (Taiwan) Ocean University; Keelung 202 Taiwan
| | - Tsung-Lin Li
- Genomics Research Center; Academia Sinica; Taipei 115 Taiwan
- Biotechnology Center; National Chung Hsing University; Taichung City 402 Taiwan
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Gehrke S, Hollóczki O. Treten in der N-heterozyklischen Carben-Organokatalyse wirklich Carbene auf? Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201708305] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sascha Gehrke
- Mulliken Center für Theoretische Chemie; Rheinische Friedrich-Wilhelms-Universität Bonn; Beringstraße 4+6 53115 Bonn Deutschland
- Max-Planck-Institut für Chemische Energiekonversion; Stiftstraße 34-36 45470 Mülheim an der Ruhr Deutschland
| | - Oldamur Hollóczki
- Mulliken Center für Theoretische Chemie; Rheinische Friedrich-Wilhelms-Universität Bonn; Beringstraße 4+6 53115 Bonn Deutschland
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32
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Gehrke S, Hollóczki O. Are There Carbenes in N-Heterocyclic Carbene Organocatalysis? Angew Chem Int Ed Engl 2017; 56:16395-16398. [PMID: 29072807 DOI: 10.1002/anie.201708305] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 10/23/2017] [Indexed: 11/08/2022]
Abstract
Azolium cations are widely employed in organocatalysis to catalyse highly valuable synthetic processes in the presence of a base. These reactions are called "N-heterocyclic carbene catalysis", based on the assumption that they are initiated by the formation of a free carbene through deprotonation, which can then react with the substrates and thereby affect their reactivity to obtain the desired products. However, we herein provide evidence that an electrophilic aromatic substitution mechanism is energetically more favourable, in which the azolium cation reacts directly with the substrate, avoiding the formation of the free carbene in solution.
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Affiliation(s)
- Sascha Gehrke
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstrasse 4+6, 53115, Bonn, Germany.,Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470, Muelheim an der Ruhr, Germany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstrasse 4+6, 53115, Bonn, Germany
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33
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Paulikat M, Wechsler C, Tittmann K, Mata RA. Theoretical Studies of the Electronic Absorption Spectra of Thiamin Diphosphate in Pyruvate Decarboxylase. Biochemistry 2017; 56:1854-1864. [PMID: 28296385 DOI: 10.1021/acs.biochem.6b00984] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Electronic absorption spectra are oftentimes used to identify reaction intermediates or substrates/products in enzymatic systems, as long as absorption bands can be unequivocally assigned to the species being studied. The latter task is far from trivial given the transient nature of some states and the complexity of the surrounding environment around the active site. To identify unique spectral fingerprints, controlled experiments with model compounds have been used in the past, but even these can sometimes be unreliable. Circular dichroism (CD) and ultraviolet-visible spectra have been tools of choice in the study of the rich chemistry of thiamin diphosphate-dependent enzymes. In this study, we focus on the Zymomonas mobilis pyruvate decarboxylase, and mutant analogues thereof, as a prototypical representative of the thiamin diphosphate (ThDP) enzyme superfamily. Through the use of electronic structure methods, we analyze the nature of electronic excitations in the cofactor. We find that all the determining CD bands around the 280-340 nm spectral range correspond to charge-transfer excitations between the pyrimidine and thiazolium rings of ThDP, which, most likely, is a general property of related ThDP-dependent enzymes. While we can confirm the assignments of previously proposed bands to chemical states, our calculations further suggest that a hitherto unassigned band of enzyme-bound ThDP reports on the ionization state of the canonical glutamate that is required for cofactor activation. This finding expands the spectroscopic "library" of chemical states of ThDP enzymes, permitting a simultaneous assignment of both the cofactor ThDP and the activating glutamate. We anticipate this finding to be helpful for mechanistic analyses of related ThDP enzymes.
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Affiliation(s)
- Mirko Paulikat
- Institute of Physical Chemistry, University of Goettingen , Tammannstraße 6, D-37077 Göttingen, Germany
| | - Cindy Wechsler
- Department of Molecular Enzymology, Albrecht-von-Haller-Institute for Plant Sciences, and Göttingen Center for Molecular Biosciences, University of Goettingen , Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany
| | - Kai Tittmann
- Department of Molecular Enzymology, Albrecht-von-Haller-Institute for Plant Sciences, and Göttingen Center for Molecular Biosciences, University of Goettingen , Julia-Lermontowa-Weg 3, D-37077 Göttingen, Germany
| | - Ricardo A Mata
- Institute of Physical Chemistry, University of Goettingen , Tammannstraße 6, D-37077 Göttingen, Germany
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34
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Mechanistic and Structural Insight to an Evolved Benzoylformate Decarboxylase with Enhanced Pyruvate Decarboxylase Activity. Catalysts 2016. [DOI: 10.3390/catal6120190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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35
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White JK, Handa S, Vankayala SL, Merkler DJ, Woodcock HL. Thiamin Diphosphate Activation in 1-Deoxy-d-xylulose 5-Phosphate Synthase: Insights into the Mechanism and Underlying Intermolecular Interactions. J Phys Chem B 2016; 120:9922-34. [PMID: 27537621 PMCID: PMC5379999 DOI: 10.1021/acs.jpcb.6b07248] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
1-Deoxy-d-xylulose 5-phosphate synthase (DXS) is a thiamin diphosphate (TDP) dependent enzyme that marks the beginning of the methylerythritol 4-phosphate isoprenoid biosynthesis pathway. The mechanism of action for DXS is still poorly understood and begins with the formation of a thiazolium ylide. This TDP activation step is thought to proceed through an intramolecular deprotonation by the 4'-aminopyrimidine ring of TDP; however, this step would occur only after an initial deprotonation of its own 4'-amino group. The mechanism of the initial deprotonation has been hypothesized, by analogy to transketolases, to occur via a histidine or an active site water molecule. Results from hybrid quantum mechanical/molecular mechanical (QM/MM) reaction path calculations reveal an ∼10 kcal/mol difference in transition state energies, favoring a water mediated mechanism over direct deprotonation by histidine. This difference was determined to be largely governed by electrostatic changes induced by conformational variations in the active site. Additionally, mutagenesis studies reveal DXS to be an evolutionarily resilient enzyme. Particularly, we hypothesize that residues H82 and H304 may act in a compensatory fashion if the other is lost due to mutation. Further, nucleus-independent chemical shifts (NICSs) and aromatic stabilization energy (ASE) calculations suggest that reduction in TDP aromaticity also serves as a factor for regulating ylide formation and controlling reactivity.
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Affiliation(s)
- Justin K. White
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - Sumit Handa
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
- Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0332, United States
| | - Sai Lakshmana Vankayala
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - David J. Merkler
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
| | - H. Lee Woodcock
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, CHE205, Tampa, Florida 33620-5250, United States
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36
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Moerdyk JP, Schilter D, Bielawski CW. N,N'-Diamidocarbenes: Isolable Divalent Carbons with Bona Fide Carbene Reactivity. Acc Chem Res 2016; 49:1458-68. [PMID: 27409520 DOI: 10.1021/acs.accounts.6b00080] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Since the first reported isolation of a carbene just over a quarter century ago, the study of such compounds-including stable derivatives-has flourished. Indeed, N-heterocyclic carbenes (NHCs), of which imidazolylidenes and their derivatives are the most pervasive subclass, feature prominently in organocatalysis, as ligands for transition metal catalysts, and as stabilizers of reactive species. However, imidazolylidenes (and many other NHCs) typically lack the reactivity characteristic of electrophilic carbenes, including insertion into unactivated C-H bonds, participation in [2 + 1] cycloadditions, and reaction with carbon monoxide. This has led to debates over whether NHCs are truly carbenic in nature or perhaps better regarded as ylides. The fundamental and synthetic utility of transformations that involve electrophilic carbenes has motivated our group and others to expand the reactivity of NHCs and other stable carbenes to encompass electrophilic carbene chemistry. These efforts have led to the development of the diamidocarbenes (DACs), a stable and unique subset of the NHCs that feature carbonyl groups inserted into the N-heterocyclic scaffold. To date, crystalline five-, six-, and seven-membered DACs have been prepared and studied. Unlike imidazolylidenes, which are often designated as prototypical NHCs, the DACs exhibit a reactivity profile similar to that of bona fide carbenes, reactive species that are less "tamed" by heteroatom π conjugation. The DACs engage in [2 + 1] cycloadditions with electron-rich or -poor alkenes, aldehydes, alkynes, and nitriles, and doing so in a reversible manner in some cases. They also react with isonitriles, reversibly couple to CO, and mediate the dehydrogenation of hydrocarbons. Such rich chemistry may be rationalized in terms of their ambiphilicity: DACs are nucleophilic, as required for some of the reactions above, yet also have electrophilic character, as evidenced by their insertions into unactivated N-H and C-H bonds, including nonacidic derivatives. As will become clear, such reactivity is unique among isolable carbenes. DAC chemistry is expected to find applications in synthesis, dynamic covalent chemistry, and catalysis. For example, the hydrolysis of DAC-derived diamidocyclopropanes and -propenes affords carboxylic acids and cyclopropenones, respectively. These new hydrocarboxylation and carbonylation methodologies are significant in that they represent alternatives to processes that typically involve precious metals and gaseous carbon monoxide. Future efforts in this area may involve modifications that transform the stoichiometric conversions facilitated by DACs into catalytic variants. In this context, the reversible binding of CO to DACs is an indication that the latter may serve as a blueprint for the development of more electrophilic, stable carbenes with the capacity to activate other challenging small molecules.
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Affiliation(s)
- Jonathan P. Moerdyk
- Department
of Chemistry, Seton Hill University, Greensburg, Pennsylvania 15601, United States
| | - David Schilter
- Center
for Multidimensional Carbon Materials (CMCM), Institute for Basic
Science (IBS), Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Christopher W. Bielawski
- Center
for Multidimensional Carbon Materials (CMCM), Institute for Basic
Science (IBS), Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
- Department
of Chemistry and Department of Energy Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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37
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Nauton L, Hélaine V, Théry V, Hecquet L. Insights into the Thiamine Diphosphate Enzyme Activation Mechanism: Computational Model for Transketolase Using a Quantum Mechanical/Molecular Mechanical Method. Biochemistry 2016; 55:2144-52. [PMID: 26998737 DOI: 10.1021/acs.biochem.5b00787] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We propose the first computational model for transketolase (TK), a thiamine diphosphate (ThDP)-dependent enzyme, using a quantum mechanical/molecular mechanical method on the basis of crystallographic TK structures from yeast and Escherichia coli, together with experimental kinetic data reported in the literature with wild-type and mutant TK. This model allowed us to define a new route for ThDP activation in the enzyme environment. We evidenced a strong interaction between ThDP and Glu418B of the TK active site, itself stabilized by Glu162A. The crucial point highlighted here is that deprotonation of ThDP C2 is not performed by ThDP N4' as reported in the literature, but by His481B, involving a HOH688A molecule bridge. Thus, ThDP N4' is converted from an amino form to an iminium form, ensuring the stabilization of the C2 carbanion or carbene. Finally, ThDP activation proceeds via an intermolecular process and not by an intramolecular one as reported in the literature. More generally, this proposed ThDP activation mechanism can be applied to some other ThDP-dependent enzymes and used to define the entire TK mechanism with donor and acceptor substrates more accurately.
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Affiliation(s)
- Lionel Nauton
- Université Clermont Auvergne, Université Blaise-Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS , UMR 6296, ICCF, F-63178 Aubiere, France
| | - Virgil Hélaine
- Université Clermont Auvergne, Université Blaise-Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS , UMR 6296, ICCF, F-63178 Aubiere, France
| | - Vincent Théry
- Université Clermont Auvergne, Université Blaise-Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS , UMR 6296, ICCF, F-63178 Aubiere, France
| | - Laurence Hecquet
- Université Clermont Auvergne, Université Blaise-Pascal , Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand, France.,CNRS , UMR 6296, ICCF, F-63178 Aubiere, France
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38
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Wechsler C, Meyer D, Loschonsky S, Funk LM, Neumann P, Ficner R, Brodhun F, Müller M, Tittmann K. Tuning and Switching Enantioselectivity of Asymmetric Carboligation in an Enzyme through Mutational Analysis of a Single Hot Spot. Chembiochem 2015; 16:2580-4. [DOI: 10.1002/cbic.201500529] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Cindy Wechsler
- Abt. Molekulare Enzymologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Danilo Meyer
- Abt. Molekulare Enzymologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Sabrina Loschonsky
- Institut für Pharmazeutische Wissenschaften; Albert-Ludwigs-Universität Freiburg; Albertstrasse 25 79104 Freiburg im Breisgau Germany
| | - Lisa-Marie Funk
- Abt. Molekulare Enzymologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Piotr Neumann
- Abt. Molekulare Strukturbiologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Ralf Ficner
- Abt. Molekulare Strukturbiologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Florian Brodhun
- Abt. Molekulare Enzymologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
| | - Michael Müller
- Institut für Pharmazeutische Wissenschaften; Albert-Ludwigs-Universität Freiburg; Albertstrasse 25 79104 Freiburg im Breisgau Germany
| | - Kai Tittmann
- Abt. Molekulare Enzymologie; Georg-August-Universität Göttingen; Justus-von-Liebig-Weg 11 37077 Göttingen Germany
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39
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Wallace S, Balskus EP. Interfacing Microbial Styrene Production with a Biocompatible Cyclopropanation Reaction. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201502185] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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40
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Wallace S, Balskus EP. Interfacing microbial styrene production with a biocompatible cyclopropanation reaction. Angew Chem Int Ed Engl 2015; 54:7106-9. [PMID: 25925138 DOI: 10.1002/anie.201502185] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2015] [Indexed: 01/04/2023]
Abstract
The introduction of new reactivity into living organisms is a major challenge in synthetic biology. Despite an increasing interest in both the development of small-molecule catalysts that are compatible with aqueous media and the engineering of enzymes to perform new chemistry in vitro, the integration of non-native reactivity into metabolic pathways for small-molecule production has been underexplored. Herein we report a biocompatible iron(III) phthalocyanine catalyst capable of efficient olefin cyclopropanation in the presence of a living microorganism. By interfacing this catalyst with E. coli engineered to produce styrene, we synthesized non-natural phenyl cyclopropanes directly from D-glucose in single-vessel fermentations. This process is the first example of the combination of nonbiological carbene-transfer reactivity with cellular metabolism for small-molecule production.
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Affiliation(s)
- Stephen Wallace
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138 (USA) http://scholar.harvard.edu/balskus
| | - Emily P Balskus
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA 02138 (USA) http://scholar.harvard.edu/balskus.
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41
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Neumann P, Tittmann K. Marvels of enzyme catalysis at true atomic resolution: distortions, bond elongations, hidden flips, protonation states and atom identities. Curr Opin Struct Biol 2014; 29:122-33. [PMID: 25460275 DOI: 10.1016/j.sbi.2014.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 10/31/2014] [Accepted: 11/03/2014] [Indexed: 10/24/2022]
Abstract
Although general principles of enzyme catalysis are fairly well understood nowadays, many important details of how exactly the substrate is bound and processed in an enzyme remain often invisible and as such elusive. In fortunate cases, structural analysis of enzymes can be accomplished at true atomic resolution thus making possible to shed light on otherwise concealed fine-structural traits of bound substrates, intermediates, cofactors and protein groups. We highlight recent structural studies of enzymes using ultrahigh-resolution X-ray protein crystallography showcasing its enormous potential as a tool in the elucidation of enzymatic mechanisms and in unveiling fundamental principles of enzyme catalysis. We discuss the observation of seemingly hyper-reactive, physically distorted cofactors and intermediates with elongated scissile substrate bonds, the detection of 'hidden' conformational and chemical equilibria and the analysis of protonation states with surprising findings. In delicate cases, atomic resolution is required to unambiguously disclose the identity of atoms as demonstrated for the metal cluster in nitrogenase. In addition to the pivotal structural findings and the implications for our understanding of enzyme catalysis, we further provide a practical framework for resolution enhancement through optimized data acquisition and processing.
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Affiliation(s)
- Piotr Neumann
- Abteilung für Molekulare Strukturbiologie, Institut für Mikrobiologie und Genetik, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Justus-von-Liebig-Weg 11, Georg-August-Universität Göttingen, Göttingen D-37077, Germany.
| | - Kai Tittmann
- Abteilung Molekulare Enzymologie, Göttinger Zentrum für Molekulare Biowissenschaften (GZMB), Justus-von-Liebig-Weg 11, Georg-August-Universität Göttingen, Göttingen D-37077, Germany.
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42
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van Zyl LJ, Schubert WD, Tuffin MI, Cowan DA. Structure and functional characterization of pyruvate decarboxylase from Gluconacetobacter diazotrophicus. BMC STRUCTURAL BIOLOGY 2014; 14:21. [PMID: 25369873 PMCID: PMC4428508 DOI: 10.1186/s12900-014-0021-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 09/25/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND Bacterial pyruvate decarboxylases (PDC) are rare. Their role in ethanol production and in bacterially mediated ethanologenic processes has, however, ensured a continued and growing interest. PDCs from Zymomonas mobilis (ZmPDC), Zymobacter palmae (ZpPDC) and Sarcina ventriculi (SvPDC) have been characterized and ZmPDC has been produced successfully in a range of heterologous hosts. PDCs from the Acetobacteraceae and their role in metabolism have not been characterized to the same extent. Examples include Gluconobacter oxydans (GoPDC), G. diazotrophicus (GdPDC) and Acetobacter pasteutrianus (ApPDC). All of these organisms are of commercial importance. RESULTS This study reports the kinetic characterization and the crystal structure of a PDC from Gluconacetobacter diazotrophicus (GdPDC). Enzyme kinetic analysis indicates a high affinity for pyruvate (K M 0.06 mM at pH 5), high catalytic efficiencies (1.3 • 10(6) M(-1) • s(-1) at pH 5), pHopt of 5.5 and Topt at 45°C. The enzyme is not thermostable (T½ of 18 minutes at 60°C) and the calculated number of bonds between monomers and dimers do not give clear indications for the relatively lower thermostability compared to other PDCs. The structure is highly similar to those described for Z. mobilis (ZmPDC) and A. pasteurianus PDC (ApPDC) with a rmsd value of 0.57 Å for Cα when comparing GdPDC to that of ApPDC. Indole-3-pyruvate does not serve as a substrate for the enzyme. Structural differences occur in two loci, involving the regions Thr341 to Thr352 and Asn499 to Asp503. CONCLUSIONS This is the first study of the PDC from G. diazotrophicus (PAL5) and lays the groundwork for future research into its role in this endosymbiont. The crystal structure of GdPDC indicates the enzyme to be evolutionarily closely related to homologues from Z. mobilis and A. pasteurianus and suggests strong selective pressure to keep the enzyme characteristics in a narrow range. The pH optimum together with reduced thermostability likely reflect the host organisms niche and conditions under which these properties have been naturally selected for. The lack of activity on indole-3-pyruvate excludes this decarboxylase as the enzyme responsible for indole acetic acid production in G. diazotrophicus.
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Affiliation(s)
- Leonardo J van Zyl
- Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Robert Sobukwe Road, Bellville, Cape Town, South Africa.
| | - Wolf-Dieter Schubert
- Department of Biochemistry, University of Pretoria, 2 Lynnwood Road, Pretoria, 0002, South Africa.
| | - Marla I Tuffin
- Institute for Microbial Biotechnology and Metagenomics (IMBM), University of the Western Cape, Robert Sobukwe Road, Bellville, Cape Town, South Africa.
| | - Don A Cowan
- Department of Genetics, University of Pretoria, Pretoria, 0002, South Africa.
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Tittmann K. Sweet siblings with different faces: the mechanisms of FBP and F6P aldolase, transaldolase, transketolase and phosphoketolase revisited in light of recent structural data. Bioorg Chem 2014; 57:263-280. [PMID: 25267444 DOI: 10.1016/j.bioorg.2014.09.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 08/25/2014] [Accepted: 09/01/2014] [Indexed: 10/24/2022]
Abstract
Nature has evolved different strategies for the reversible cleavage of ketose phosphosugars as essential metabolic reactions in all domains of life. Prominent examples are the Schiff-base forming class I FBP and F6P aldolase as well as transaldolase, which all exploit an active center lysine to reversibly cleave the C3-C4 bond of fructose-1,6-bisphosphate or fructose-6-phosphate to give two 3-carbon products (aldolase), or to shuttle 3-carbon units between various phosphosugars (transaldolase). In contrast, transketolase and phosphoketolase make use of the bioorganic cofactor thiamin diphosphate to cleave the preceding C2-C3 bond of ketose phosphates. While transketolase catalyzes the reversible transfer of 2-carbon ketol fragments in a reaction analogous to that of transaldolase, phosphoketolase forms acetyl phosphate as final product in a reaction that comprises ketol cleavage, dehydration and phosphorolysis. In this review, common and divergent catalytic principles of these enzymes will be discussed, mostly, but not exclusively, on the basis of crystallographic snapshots of catalysis. These studies in combination with mutagenesis and kinetic analysis not only delineated the stereochemical course of substrate binding and processing, but also identified key catalytic players acting at the various stages of the reaction. The structural basis for the different chemical fates and lifetimes of the central enamine intermediates in all five enzymes will be particularly discussed, in addition to the mechanisms of substrate cleavage, dehydration and ring-opening reactions of cyclic substrates. The observation of covalent enzymatic intermediates in hyperreactive conformations such as Schiff-bases with twisted double-bond linkages in transaldolase and physically distorted substrate-thiamin conjugates with elongated substrate bonds to be cleaved in transketolase, which probably epitomize a canonical feature of enzyme catalysis, will be also highlighted.
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Affiliation(s)
- Kai Tittmann
- Göttingen Center for Molecular Biosciences, Georg-August University Göttingen, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany.
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44
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Jordan F, Nemeria NS. Progress in the experimental observation of thiamin diphosphate-bound intermediates on enzymes and mechanistic information derived from these observations. Bioorg Chem 2014; 57:251-262. [PMID: 25228115 DOI: 10.1016/j.bioorg.2014.08.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 08/11/2014] [Indexed: 11/26/2022]
Abstract
Thiamin diphosphate (ThDP), the vitamin B1 coenzyme is an excellent representative of coenzymes, which carry out electrophilic catalysis by forming a covalent complex with their substrates. The function of ThDP is to greatly increase the acidity of two carbon acids by stabilizing their conjugate bases, the ylide/carbene/C2-carbanion of the thiazolium ring and the C2α-carbanion/enamine, once the substrate binds to ThDP. In recent years, several ThDP-bound intermediates on such pathways have been characterized by both solution and solid-state methods. Prominent among these advances are X-ray crystallographic results identifying both oxidative and non-oxidative intermediates, rapid chemical quench followed by NMR detection of several intermediates which are stable under acidic conditions, solid-state NMR and circular dichroism detection of the states of ionization and tautomerization of the 4'-aminopyrimidine moiety of ThDP in some of the intermediates. These methods also enabled in some cases determination of the rate-limiting step in the complex series of steps. This review is an update of a review with the same title published by the authors in 2005 in this Journal. Much progress has been made in the intervening decade in the identification of the intermediates and their application to gain additional mechanistic insight.
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Affiliation(s)
- Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ 07102, USA.
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Gutiérrez A, Gimeno MC, Marzo I, Metzler-Nolte N. Synthesis, Characterization, and Cytotoxic Activity of AuIN,S-Heterocyclic Carbenes Derived from Peptides ContainingL-Thiazolylalanine. Eur J Inorg Chem 2014. [DOI: 10.1002/ejic.201402103] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Patel H, Nemeria NS, Andrews FH, McLeish MJ, Jordan F. Identification of charge transfer transitions related to thiamin-bound intermediates on enzymes provides a plethora of signatures useful in mechanistic studies. Biochemistry 2014; 53:2145-52. [PMID: 24628377 PMCID: PMC3985856 DOI: 10.1021/bi4015743] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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Identification
of enzyme-bound intermediates via their spectroscopic
signatures, which then allows direct monitoring of the kinetic fate
of these intermediates, poses a continuing challenge. As an electrophilic
covalent catalyst, the thiamin diphosphate (ThDP) coenzyme forms a
number of noncovalent and covalent intermediates along its reaction
pathways, and multiple UV–vis and circular dichroism (CD) bands
have been identified at Rutgers pertinent to several among them. These
electronic transitions fall into two classes: those for which the
conjugated system provides a reasonable guide to the observed λmax and others in which there is no corresponding conjugated
system and the observed CD bands are best ascribed to charge transfer
(CT) transitions. Herein is reported the reaction of four ThDP enzymes
with alternate substrates: (a) acetyl pyruvate, its methyl ester,
and fluoropyruvate, these providing the shortest side chains attached
at the thiazolium C2 atom and leading to CT bands with λmax values of >390 nm, not pertinent to any on-pathway conjugated
systems (estimated λmax values of <330 nm), and
(b) (E)-4-(4-chlorophenyl)-2-oxo-3-butenoic acid
displaying both a conjugated enamine (430 nm) and a CT transition
(480 nm). We suggest that the CT transitions result from an interaction
of the π bond on the ThDP C2 side chain as a donor, and the
positively charged thiazolium ring as an acceptor, and correspond
to covalent ThDP-bound intermediates. Time resolution of these bands
allows the rate constants for individual steps to be determined. These
CD methods can be applied to the entire ThDP superfamily of enzymes
and should find applications with other enzymes.
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Affiliation(s)
- Hetalben Patel
- Department of Chemistry, Rutgers, the State University of New Jersey , Newark, New Jersey 07102, United States
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Jordan F, Nemeria NS. Experimental observation of thiamin diphosphate-bound intermediates on enzymes and mechanistic information derived from these observations. Bioorg Chem 2005; 33:190-215. [PMID: 15888311 PMCID: PMC4189838 DOI: 10.1016/j.bioorg.2005.02.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2004] [Revised: 02/08/2005] [Accepted: 02/10/2005] [Indexed: 11/27/2022]
Abstract
Thiamin diphosphate (ThDP), the vitamin B1 coenzyme, is an excellent representative of coenzymes, which carry out electrophilic catalysis by forming a covalent complex with their substrates. The function of ThDP is to greatly increase the acidity of two carbon acids by stabilizing their conjugate bases, the ylide/C2-carbanion of the thiazolium ring and the C2alpha-carbanion (or enamine) once the substrate binds to ThDP. In recent years, several ThDP-bound intermediates on such pathways have been characterized by both solution and solid-state (X-ray) methods. Prominent among these advances are X-ray crystallographic results identifying both oxidative and non-oxidative intermediates, rapid chemical quench followed by NMR detection of a several intermediates which are stable under acidic conditions, and circular dichroism detection of the 1',4'-imino tautomer of ThDP in some of the intermediates. Some of these methods also enable the investigator to determine the rate-limiting step in the complex series of steps.
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Affiliation(s)
- Frank Jordan
- Department of Chemistry, Rutgers University, Newark, NJ 07102, USA
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