1
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Bowling PE, Dasgupta S, Herbert JM. Eliminating Imaginary Vibrational Frequencies in Quantum-Chemical Cluster Models of Enzymatic Active Sites. J Chem Inf Model 2024; 64:3912-3922. [PMID: 38648614 DOI: 10.1021/acs.jcim.4c00221] [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: 04/25/2024]
Abstract
In constructing finite models of enzyme active sites for quantum-chemical calculations, atoms at the periphery of the model must be constrained to prevent unphysical rearrangements during geometry relaxation. A simple fixed-atom or "coordinate-lock" approach is commonly employed but leads to undesirable artifacts in the form of small imaginary frequencies. These preclude evaluation of finite-temperature free-energy corrections, limiting thermochemical calculations to enthalpies only. Full-dimensional vibrational frequency calculations are possible by replacing the fixed-atom constraints with harmonic confining potentials. Here, we compare that approach to an alternative strategy in which fixed-atom contributions to the Hessian are simply omitted. While the latter strategy does eliminate imaginary frequencies, it tends to underestimate both the zero-point energy and the vibrational entropy while introducing artificial rigidity. Harmonic confining potentials eliminate imaginary frequencies and provide a flexible means to construct active-site models that can be used in unconstrained geometry relaxations, affording better convergence of reaction energies and barrier heights with respect to the model size, as compared to models with fixed-atom constraints.
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Affiliation(s)
- Paige E Bowling
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
| | - Saswata Dasgupta
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, California 92093, United States
| | - John M Herbert
- Biophysics Graduate Program, The Ohio State University, Columbus, Ohio 43210, United States
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, Ohio 43210, United States
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2
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Mrowicka M, Mrowicki J, Dragan G, Majsterek I. The importance of thiamine (vitamin B1) in humans. Biosci Rep 2023; 43:BSR20230374. [PMID: 37389565 PMCID: PMC10568373 DOI: 10.1042/bsr20230374] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/11/2023] [Accepted: 06/14/2023] [Indexed: 07/01/2023] Open
Abstract
Thiamine (thiamin, B1) is a vitamin necessary for proper cell function. It exists in a free form as a thiamine, or as a mono-, di- or triphosphate. Thiamine plays a special role in the body as a coenzyme necessary for the metabolism of carbohydrates, fats and proteins. In addition, it participates in the cellular respiration and oxidation of fatty acids: in malnourished people, high doses of glucose result in acute thiamine deficiency. It also participates in energy production in the mitochondria and protein synthesis. In addition, it is also needed to ensure the proper functioning of the central and peripheral nervous system, where it is involved in neurotransmitter synthesis. Its deficiency leads to mitochondrial dysfunction, lactate and pyruvate accumulation, and consequently to focal thalamic degeneration, manifested as Wernicke's encephalopathy or Wernicke-Korsakoff syndrome. It can also lead to severe or even fatal neurologic and cardiovascular complications, including heart failure, neuropathy leading to ataxia and paralysis, confusion, or delirium. The most common risk factor for thiamine deficiency is alcohol abuse. This paper presents current knowledge of the biological functions of thiamine, its antioxidant properties, and the effects of its deficiency in the body.
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Affiliation(s)
- Małgorzata Mrowicka
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
| | - Jerzy Mrowicki
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
| | - Grzegorz Dragan
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
| | - Ireneusz Majsterek
- Małgorzata Mrowicka, Jerzy Mrowicki, Grzegorz Dragan, Ireneusz Majsterek, Department of Clinical Chemistry and Biochemistry, Medical University of Lodz, Mazowiecka 5, 92-215 Lodz, Poland
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3
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Abstract
ConspectusThe quantum chemical cluster approach has been used for modeling enzyme active sites and reaction mechanisms for more than two decades. In this methodology, a relatively small part of the enzyme around the active site is selected as a model, and quantum chemical methods, typically density functional theory, are used to calculate energies and other properties. The surrounding enzyme is modeled using implicit solvation and atom fixing techniques. Over the years, a large number of enzyme mechanisms have been solved using this method. The models have gradually become larger as a result of the faster computers, and new kinds of questions have been addressed. In this Account, we review how the cluster approach can be utilized in the field of biocatalysis. Examples from our recent work are chosen to illustrate various aspects of the methodology. The use of the cluster model to explore substrate binding is discussed first. It is emphasized that a comprehensive search is necessary in order to identify the lowest-energy binding mode(s). It is also argued that the best binding mode might not be the productive one, and the full reactions for a number of enzyme-substrate complexes have therefore to be considered to find the lowest-energy reaction pathway. Next, examples are given of how the cluster approach can help in the elucidation of detailed reaction mechanisms of biocatalytically interesting enzymes, and how this knowledge can be exploited to develop enzymes with new functions or to understand the reasons for lack of activity toward non-natural substrates. The enzymes discussed in this context are phenolic acid decarboxylase and metal-dependent decarboxylases from the amidohydrolase superfamily. Next, the application of the cluster approach in the investigation of enzymatic enantioselectivity is discussed. The reaction of strictosidine synthase is selected as a case study, where the cluster calculations could reproduce and rationalize the selectivities of both the natural and non-natural substrates. Finally, we discuss how the cluster approach can be used to guide the rational design of enzyme variants with improved activity and selectivity. Acyl transferase from Mycobacterium smegmatis serves as an instructive example here, for which the calculations could pinpoint the factors controlling the reaction specificity and enantioselectivity. The cases discussed in this Account highlight thus the value of the cluster approach as a tool in biocatalysis. It complements experiments and other computational techniques in this field and provides insights that can be used to understand existing enzymes and to develop new variants with tailored properties.
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Affiliation(s)
- Xiang Sheng
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, PR China
- National Center of Technology Innovation for Synthetic Biology, Tianjin 300308, PR China
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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4
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A Combined Computational–Experimental Study on the Substrate Binding and Reaction Mechanism of Salicylic Acid Decarboxylase. Catalysts 2022. [DOI: 10.3390/catal12121577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Salicylic acid decarboxylase (SDC) from the amidohydrolase superfamily (AHS) catalyzes the reversible decarboxylation of salicylic acid to form phenol. In this study, the substrate binding mode and reaction mechanism of SDC were investigated using computational and crystallographic methods. Quantum chemical calculations show that the enzyme follows the general mechanism of AHS decarboxylases. Namely, the reaction begins with proton transfer from a metal-coordinated aspartic acid residue (Asp298 in SDC) to the C1 of salicylic acid, which is followed by the C–C bond cleavage, to generate the phenol product and release CO2. Interestingly, the calculations show that SDC is a Mg-dependent enzyme rather than the previously proposed Zn-dependent, and the substrate is shown to be bidentately coordinated to the metal center in the catalysis, which is also different from the previous proposal. These predictions are corroborated by the crystal structure of SDC solved in complex with the substrate analogue 2-nitrophenol. The mechanistic insights into SDC in the present study provide important information for the rational design of the enzyme.
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5
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Prejanò M, Škerlová J, Stenmark P, Himo F. Reaction Mechanism of Human PAICS Elucidated by Quantum Chemical Calculations. J Am Chem Soc 2022; 144:14258-14268. [PMID: 35914774 PMCID: PMC9376930 DOI: 10.1021/jacs.2c05072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Human PAICS is a bifunctional enzyme that is involved
in the de novo purine biosynthesis, catalyzing the
conversion of
aminoimidazole ribonucleotide (AIR) into N-succinylcarboxamide-5-aminoimidazole
ribonucleotide (SAICAR). It comprises two distinct active sites, AIR
carboxylase (AIRc) where the AIR is initially converted to carboxyaminoimidazole
ribonucleotide (CAIR) by reaction with CO2 and SAICAR synthetase
(SAICARs) in which CAIR then reacts with an aspartate to form SAICAR,
in an ATP-dependent reaction. Human PAICS is a promising target for
the treatment of various types of cancer, and it is therefore of high
interest to develop a detailed understanding of its reaction mechanism.
In the present work, density functional theory calculations are employed
to investigate the PAICS reaction mechanism. Starting from the available
crystal structures, two large models of the AIRc and SAICARs active
sites are built and different mechanistic proposals for the carboxylation
and phosphorylation–condensation mechanisms are examined. For
the carboxylation reaction, it is demonstrated that it takes place
in a two-step mechanism, involving a C–C bond formation followed
by a deprotonation of the formed tetrahedral intermediate (known as
isoCAIR) assisted by an active site histidine residue. For the phosphorylation–condensation
reaction, it is shown that the phosphorylation of CAIR takes place
before the condensation reaction with the aspartate. It is further
demonstrated that the three active site magnesium ions are involved
in binding the substrates and stabilizing the transition states and
intermediates of the reaction. The calculated barriers are in good
agreement with available experimental data.
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Affiliation(s)
- Mario Prejanò
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Jana Škerlová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam. 2, 160 00 Prague, Czech Republic
| | - Pål Stenmark
- Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm, Sweden
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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6
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Wang Q, Geng S, Wang L, Wen Z, Sun X, Huang H. Bacterial mandelic acid degradation pathway and its application in biotechnology. J Appl Microbiol 2022; 133:273-286. [PMID: 35294082 DOI: 10.1111/jam.15529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 12/22/2021] [Accepted: 03/09/2022] [Indexed: 11/28/2022]
Abstract
Mandelic acid and its derivatives are an important class of chemical synthetic blocks, which is widely used in drug synthesis and stereochemistry research. In nature, mandelic acid degradation pathway has been widely identified and analyzed as a representative pathway of aromatic compounds degradation. The most studied mandelic acid degradation pathway from Pseudomonas putida consists of mandelate racemase, S-mandelate dehydrogenase, benzoylformate decarboxylase, benzaldehyde dehydrogenase and downstream benzoic acid degradation pathways. Because of the ability to catalyze various reactions of aromatic substrates, pathway enzymes have been widely used in biocatalysis, kinetic resolution, chiral compounds synthesis or construction of new metabolic pathways. In this paper, the physiological significance and the existing range of the mandelic acid degradation pathway were introduced first. Then each of the enzymes in the pathway is reviewed one by one, including the researches on enzymatic properties and the applications in biotechnology as well as efforts that have been made to modify the substrate specificity or improving catalytic activity by enzyme engineering to adapt different applications. The composition of the important metabolic pathway of bacterial mandelic acid degradation pathway as well as the researches and applications of pathway enzymes is summarized in this review for the first time.
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Affiliation(s)
- Qingzhuo Wang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2# Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Shanshan Geng
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2# Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Lingru Wang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2# Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Zhiqiang Wen
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2# Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - Xiaoman Sun
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2# Xuelin Road, Qixia District, Nanjing, People's Republic of China
| | - He Huang
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, 2# Xuelin Road, Qixia District, Nanjing, People's Republic of China.,College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, No. 30 South Puzhu Road, Nanjing, People's Republic of China
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7
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Modeling Catalysis in Allosteric Enzymes: Capturing Conformational Consequences. Top Catal 2021; 65:165-186. [DOI: 10.1007/s11244-021-01521-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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8
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Planas F, McLeish MJ, Himo F. Enzymatic Stetter Reaction: Computational Study of the Reaction Mechanism of MenD. ACS Catal 2021. [DOI: 10.1021/acscatal.1c02292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Ferran Planas
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-10691, Sweden
| | - Michael J. McLeish
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-10691, Sweden
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9
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Sheng X, Kazemi M, Planas F, Himo F. Modeling Enzymatic Enantioselectivity using Quantum Chemical Methodology. ACS Catal 2020. [DOI: 10.1021/acscatal.0c00983] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Xiang Sheng
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-106 91, Sweden
| | - Masoud Kazemi
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-106 91, Sweden
| | - Ferran Planas
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-106 91, Sweden
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm SE-106 91, Sweden
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10
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Dasgupta S, Herbert JM. Using Atomic Confining Potentials for Geometry Optimization and Vibrational Frequency Calculations in Quantum-Chemical Models of Enzyme Active Sites. J Phys Chem B 2020; 124:1137-1147. [PMID: 31986049 DOI: 10.1021/acs.jpcb.9b11060] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Quantum-chemical studies of enzymatic reaction mechanisms sometimes use truncated active-site models as simplified alternatives to mixed quantum mechanics molecular mechanics (QM/MM) procedures. Eliminating the MM degrees of freedom reduces the complexity of the sampling problem, but the trade-off is the need to introduce geometric constraints in order to prevent structural collapse of the model system during geometry optimizations that do not contain a full protein backbone. These constraints may impair the efficiency of the optimization, and care must be taken to avoid artifacts such as imaginary vibrational frequencies. We introduce a simple alternative in which terminal atoms of the model system are placed in soft harmonic confining potentials rather than being rigidly constrained. This modification is simple to implement and straightforward to use in vibrational frequency calculations, unlike iterative constraint-satisfaction algorithms, and allows the optimization to proceed without constraint even though the practical result is to fix the anchor atoms in space. The new approach is more efficient for optimizing minima and transition states, as compared to the use of fixed-atom constraints, and also more robust against unwanted imaginary frequencies. We illustrate the method by application to several enzymatic reaction pathways where entropy makes a significant contribution to the relevant reaction barriers. The use of confining potentials correctly describes reaction paths and facilitates calculation of both vibrational zero-point and finite-temperature entropic corrections to barrier heights.
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Affiliation(s)
- Saswata Dasgupta
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
| | - John M Herbert
- Department of Chemistry and Biochemistry , The Ohio State University , Columbus , Ohio 43210 , United States
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11
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Mendoza F, Medina FE, Jiménez VA, Jaña GA. Catalytic Role of Gln202 in the Carboligation Reaction Mechanism of Yeast AHAS: A QM/MM Study. J Chem Inf Model 2019; 60:915-922. [DOI: 10.1021/acs.jcim.9b00863] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fernanda Mendoza
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Autopista Concepción-Talcahuano, 7100 Talcahuano, Chile
| | - Fabiola E. Medina
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Autopista Concepción-Talcahuano, 7100 Talcahuano, Chile
| | - Verónica A. Jiménez
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Autopista Concepción-Talcahuano, 7100 Talcahuano, Chile
| | - Gonzalo A. Jaña
- Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andres Bello, Autopista Concepción-Talcahuano, 7100 Talcahuano, Chile
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12
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Prejanò M, Medina FE, Fernandes PA, Russo N, Ramos MJ, Marino T. The Catalytic Mechanism of Human Transketolase. Chemphyschem 2019; 20:2881-2886. [PMID: 31489766 DOI: 10.1002/cphc.201900650] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/29/2019] [Indexed: 01/10/2023]
Abstract
We have computationally determined the catalytic mechanism of human transketolase (hTK) using a cluster model approach and density functional theory calculations. We were able to determine all the relevant structures, bringing solid evidences to the proposed experimental mechanism, and to add important detail to the structure of the transition states and the energy profile associated with catalysis. Furthermore, we have established the existence of a crucial intermediate of the catalytic cycle, in agreement with experiments. The calculated data brought new insights to hTK's catalytic mechanism, providing free-energy values for the chemical reaction, as well as adding atomistic detail to the experimental mechanism.
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Affiliation(s)
- Mario Prejanò
- Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, Via Ponte Pietro Bucci, 87036, Arcavacata di Rende (CS), Italy
| | - Fabiola Estefany Medina
- UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Pedro Alexandrino Fernandes
- UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Nino Russo
- Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, Via Ponte Pietro Bucci, 87036, Arcavacata di Rende (CS), Italy
| | - Maria Joao Ramos
- UCIBIO, REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Tiziana Marino
- Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, Via Ponte Pietro Bucci, 87036, Arcavacata di Rende (CS), Italy
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13
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Wei Z, Wilkinson RC, Rashid GMM, Brown D, Fülöp V, Bugg TDH. Characterization of Thiamine Diphosphate-Dependent 4-Hydroxybenzoylformate Decarboxylase Enzymes from Rhodococcus jostii RHA1 and Pseudomonas fluorescens Pf-5 Involved in Degradation of Aryl C 2 Lignin Degradation Fragments. Biochemistry 2019; 58:5281-5293. [PMID: 30946572 DOI: 10.1021/acs.biochem.9b00177] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A thiamine diphosphate-dependent enzyme annotated as a benzoylformate decarboxylase is encoded by gene cluster ro02984-ro02986 in Rhodococcus jostii RHA1 previously shown to generate vanillin and 4-hydroxybenzaldehyde from lignin oxidation, and a closely related gene cluster is also found in the genome of Pseudomonas fluorescens Pf-5. Two hypotheses for possible pathways involving a thiamine diphosphate-dependent cleavage, either C-C cleavage of a ketol or diketone aryl C3 substrate or decarboxylation of an aryl C2 substrate, were investigated by expression and purification of the recombinant enzymes and expression of dehydrogenase and oxidase enzymes also found in the gene clusters. The ThDP-dependent enzymes showed no activity for cleavage of aryl C3 ketol or diketone substrates but showed activity for decarboxylation of benzoylformate and 4-hydroxybenzoylformate. A flavin-dependent oxidase encoded by gene ro02984 was found to oxidize either mandelic acid or phenylglyoxal. The crystal structure of the P. fluorescens decarboxylase enzyme was determined at 1.69 Å resolution, showing similarity to structures of known benzoylformate decarboxylase enzymes. The P. fluorescens decarboxylase enzyme showed enhanced carboligase activity between vanillin and acetaldehyde, rationalized by the presence of alanine versus serine at residue 73 in the enzyme active site, which was investigated further by site-directed mutagenesis of this residue. A hypothesis for a pathway for degradation of aryl C2 fragments arising from oxidative cleavage of phenylcoumaran and diarylpropane structures in lignin is proposed.
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Affiliation(s)
- Zhen Wei
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | | | - Goran M M Rashid
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | - David Brown
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
| | - Vilmos Fülöp
- School of Life Sciences , University of Warwick , Coventry CV4 7AL , U.K
| | - Timothy D H Bugg
- Department of Chemistry , University of Warwick , Coventry CV4 7AL , U.K
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14
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Planas F, McLeish MJ, Himo F. Computational Study of Enantioselective Carboligation Catalyzed by Benzoylformate Decarboxylase. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01084] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Ferran Planas
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Michael J. McLeish
- Department of Chemistry and Chemical Biology, Indiana University−Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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15
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Planas F, McLeish MJ, Himo F. Computational characterization of enzyme-bound thiamin diphosphate reveals a surprisingly stable tricyclic state: implications for catalysis. Beilstein J Org Chem 2019; 15:145-159. [PMID: 30745990 PMCID: PMC6350894 DOI: 10.3762/bjoc.15.15] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/10/2018] [Indexed: 12/05/2022] Open
Abstract
Thiamin diphosphate (ThDP)-dependent enzymes constitute a large class of enzymes that catalyze a diverse range of reactions. Many are involved in stereospecific carbon–carbon bond formation and, consequently, have found increasing interest and utility as chiral catalysts in various biocatalytic applications. All ThDP-catalyzed reactions require the reaction of the ThDP ylide (the activated state of the cofactor) with the substrate. Given that the cofactor can adopt up to seven states on an enzyme, identifying the factors affecting the stability of the pre-reactant states is important for the overall understanding of the kinetics and mechanism of the individual reactions. In this paper we use density functional theory calculations to systematically study the different cofactor states in terms of energies and geometries. Benzoylformate decarboxylase (BFDC), which is a well characterized chiral catalyst, serves as the prototypical ThDP-dependent enzyme. A model of the active site was constructed on the basis of available crystal structures, and the cofactor states were characterized in the presence of three different ligands (crystallographic water, benzoylformate as substrate, and (R)-mandelate as inhibitor). Overall, the calculations reveal that the relative stabilities of the cofactor states are greatly affected by the presence and identity of the bound ligands. A surprising finding is that benzoylformate binding, while favoring ylide formation, provided even greater stabilization to a catalytically inactive tricyclic state. Conversely, the inhibitor binding greatly destabilized the ylide formation. Together, these observations have significant implications for the reaction kinetics of the ThDP-dependent enzymes, and, potentially, for the use of unnatural substrates in such reactions.
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Affiliation(s)
- Ferran Planas
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
| | - Michael J McLeish
- Department of Chemistry and Chemical Biology, Indiana University-Purdue University Indianapolis, Indianapolis IN 46202, USA
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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