1
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Chen Q, Zhou J, Yang Z, Guo J, Liu Z, Sun X, Jiang Q, Fang L, Wang D, Xiao S. An intermolecular salt bridge linking substrate binding and P1 substrate specificity switch of arterivirus 3C-like proteases. Comput Struct Biotechnol J 2022; 20:3409-3421. [PMID: 35832618 PMCID: PMC9271976 DOI: 10.1016/j.csbj.2022.06.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 06/26/2022] [Accepted: 06/27/2022] [Indexed: 11/26/2022] Open
Abstract
Equine arteritis virus (EAV) and porcine reproductive and respiratory syndrome virus (PRRSV) represent two members of the family Arteriviridae and pose a major threat to the equine- and swine-breeding industries throughout the world. Previously, we and others demonstrated that PRRSV 3C-like protease (3CLpro) had very high glutamic acid (Glu)-specificity at the P1 position (P1-Glu). Comparably, EAV 3CLpro exhibited recognition of both Glu and glutamine (Gln) at the P1 position. However, the underlying mechanisms of the P1 substrate specificity shift of arterivirus 3CLpro remain unclear. We systematically screened the specific amino acids in the S1 subsite of arterivirus 3CLpro using a cyclized luciferase-based biosensor and identified Gly116, His133 and Ser136 (using PRRSV 3CLpro numbering) are important for recognition of P1-Glu, whereas Ser136 is nonessential for recognition of P1-Gln. Molecular dynamics simulations and biochemical experiments highlighted that the PRRSV 3CLpro and EAV 3CLpro formed distinct S1 subsites for the P1 substrate specificity switch. Mechanistically, a specific intermolecular salt bridge between PRRSV 3CLpro and substrate P1-Glu (Lys138/P1-Glu) are invaluable for high Glu-specificity at the P1 position, and the exchange of K138T (salt bridge interruption, from PRRSV to EAV) shifted the specificity of PRRSV 3CLpro toward P1-Gln. In turn, the T139K exchange of EAV 3CLpro showed a noticeable shift in substrate specificity, such that substrates containing P1-Glu are likely to be recognized more efficiently. These findings identify an evolutionarily accessible mechanism for disrupting or reorganizing salt bridge with only a single mutation of arterivirus 3CLpro to trigger a substrate specificity switch.
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Affiliation(s)
- Qian Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Junwei Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Zhixiang Yang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Jiahui Guo
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Zimin Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Xinyi Sun
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Qingshi Jiang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Liurong Fang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Dang Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
| | - Shaobo Xiao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.,Key Laboratory of Preventive Veterinary Medicine in Hubei Province, The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, China
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2
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Brochier-Armanet C, Madern D. Phylogenetics and biochemistry elucidate the evolutionary link between l-malate and l-lactate dehydrogenases and disclose an intermediate group of sequences with mix functional properties. Biochimie 2021; 191:140-153. [PMID: 34418486 DOI: 10.1016/j.biochi.2021.08.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 07/19/2021] [Accepted: 08/15/2021] [Indexed: 01/23/2023]
Abstract
The NAD(P)-dependent malate dehydrogenases (MDH) (EC 1.1.1.37) and NAD-dependent lactate dehydrogenases (LDH) (EC. 1.1.1.27) form a large superfamily that has been characterized in organisms belonging to the three Domains of Life. MDH catalyzes the reversible conversion of the oxaloacetate into malate, while LDH operates at the late stage of glycolysis by converting pyruvate into lactate. Phylogenetic studies proposed that the LDH/MDH superfamily encompasses five main groups of enzymes. Here, starting from 16,052 reference proteomes, we reinvestigated the relationships between MDH and LDH. We showed that the LDH/MDH superfamily encompasses three main families: MDH1, MDH2, and a large family encompassing MDH3, LDH, and L-2-hydroxyisocaproate dehydrogenases (HicDH) sequences. An in-depth analysis of the phylogeny of the MDH3/LDH/HicDH family and of the nature of three important amino acids, located within the catalytic site and involved in binding and substrate discrimination, revealed a large group of sequences displaying unexpected combinations of amino acids at these three critical positions. This group branched in-between canonical MDH3 and LDH sequences. The functional characterization of several enzymes from this intermediate group disclosed a mix of functional properties, indicating that the MDH3/LDH/HicDH family is much more diverse than previously thought, and blurred the frontier between MDH3 and LDH enzymes. Present-days enzymes of the intermediate group are a valuable material to study the evolutionary steps that led to functional diversity and emergence of allosteric regulation within the LDH/MDH superfamily.
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Affiliation(s)
- Céline Brochier-Armanet
- Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Évolutive UMR 5558, F-69622, Villeurbanne, France.
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3
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Al-Ayoubi SR, Schummel PH, Cisse A, Seydel T, Peters J, Winter R. Osmolytes modify protein dynamics and function of tetrameric lactate dehydrogenase upon pressurization. Phys Chem Chem Phys 2019; 21:12806-12817. [PMID: 31165827 DOI: 10.1039/c9cp02310k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We present a study of the combined effects of natural cosolvents (TMAO, glycine, urea) and pressure on the activity of the tetrameric enzyme lactate dehydrogenase (LDH). To this end, high-pressure stopped-flow methodology in concert with fast UV/Vis spectroscopic detection of product formation was applied. To reveal possible pressure effects on the stability and dynamics of the enzyme, FTIR spectroscopic and neutron scattering measurements were carried out. In neat buffer solution, the catalytic turnover number of the enzyme, kcat, increases up to 1000 bar, the pressure range where dissociation of the tetrameric species to dimers sets in. Accordingly, we obtain a negative activation volume, ΔV# = -45.3 mL mol-1. Further, the enzyme substrate complex has a larger volume compared to the enzyme and substrate in the unbound state. The neutron scattering data show that changes in the fast internal dynamics of the enzyme are not responsible for the increase of kcat upon compression. Whereas the magnitude of kcat is similar in the presence of the osmolytes, the pressure of deactivation is modulated by the addition of cosolvents. TMAO and glycine increase the pressure of deactivation, and in accordance with the observed stabilizing effect both cosolvents exhibit against denaturation and/or dissociation of proteins. While urea does not markedly affect the magnitude of the Michaelis constant, KM, both 1 M TMAO and 1 M glycine exhibit smaller KM values of about 0.07 mM and 0.05 mM below about 1 kbar. Such positive effect on the substrate affinity could be rationalized by the effect the two cosolutes impose on the thermodynamic activities of the reactants, which reflect changes in water-mediated intermolecular interactions. Our data show that the intracellular milieu, i.e., the solution conditions that have evolved, may be sufficient to maintain enzymatic activity under extreme environmental conditions, including the whole pressure range encountered on Earth.
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Affiliation(s)
- Samy R Al-Ayoubi
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Str. 4a, 44227 Dortmund, Germany.
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4
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Akai S, Ikushiro H, Sawai T, Yano T, Kamiya N, Miyahara I. The crystal structure of homoserine dehydrogenase complexed with l-homoserine and NADPH in a closed form. J Biochem 2019; 165:185-195. [PMID: 30423116 DOI: 10.1093/jb/mvy094] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 11/08/2018] [Indexed: 12/18/2022] Open
Abstract
Homoserine dehydrogenase from Thermus thermophilus (TtHSD) is a key enzyme in the aspartate pathway that catalyses the reversible conversion of l-aspartate-β-semialdehyde to l-homoserine (l-Hse) with NAD(P)H. We determined the crystal structures of unliganded TtHSD, TtHSD complexed with l-Hse and NADPH, and Lys99Ala and Lys195Ala mutant TtHSDs, which have no enzymatic activity, complexed with l-Hse and NADP+ at 1.83, 2.00, 1.87 and 1.93 Å resolutions, respectively. Binding of l-Hse and NADPH induced the conformational changes of TtHSD from an open to a closed form: the mobile loop containing Glu180 approached to fix l-Hse and NADPH, and both Lys99 and Lys195 could make hydrogen bonds with the hydroxy group of l-Hse. The ternary complex of TtHSDs in the closed form mimicked a Michaelis complex better than the previously reported open form structures from other species. In the crystal structure of Lys99Ala TtHSD, the productive geometry of the ternary complex was almost preserved with one new water molecule taking over the hydrogen bonds associated with Lys99, while the positions of Lys195 and l-Hse were significantly retained with those of the wild-type enzyme. These results propose new possibilities that Lys99 is the acid-base catalytic residue of HSDs.
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Affiliation(s)
- Shota Akai
- Graduate School of Science, Osaka City University, Osaka, Japan
| | - Hiroko Ikushiro
- Depertment of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, Japan
| | - Taiki Sawai
- Depertment of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, Japan
| | - Takato Yano
- Depertment of Biochemistry, Faculty of Medicine, Osaka Medical College, Osaka, Japan
| | - Nobuo Kamiya
- Graduate School of Science, Osaka City University, Osaka, Japan.,The OCU Advanced Research Institute for Natural Science and Technology, Osaka City University, Osaka, Japan
| | - Ikuko Miyahara
- Graduate School of Science, Osaka City University, Osaka, Japan
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5
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Peng HL, Callender R. Mechanistic Analysis of Fluorescence Quenching of Reduced Nicotinamide Adenine Dinucleotide by Oxamate in Lactate Dehydrogenase Ternary Complexes. Photochem Photobiol 2017; 93:1193-1203. [PMID: 28391608 PMCID: PMC5603363 DOI: 10.1111/php.12775] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 03/11/2017] [Indexed: 11/27/2022]
Abstract
Fluorescence of Reduced Nicotinamide Adenine Dinucleotide (NADH) is extensively employed in studies of oxidoreductases. A substantial amount of static and kinetic work has focused on the binding of pyruvate or substrate mimic oxamate to the binary complex of lactate dehydrogenase (LDH)-NADH where substantial fluorescence quenching is typically observed. However, the quenching mechanism is not well understood limiting structural interpretation. Based on time-dependent density functional theory (TDDFT) computations with cam-B3LYP functional in conjunction with the analysis of previous experimental results, we propose that bound oxamate acts as an electron acceptor in the quenching of fluorescence of NADH in the ternary complex, where a charge transfer (CT) state characterized by excitation from the highest occupied molecular orbital (HOMO) of the nicotinamide moiety of NADH to the lowest unoccupied molecular orbital (LUMO) of oxamate exists close to the locally excited (LE) state involving only the nicotinamide moiety. Efficient quenching in the encounter complex like in pig heart LDH requires that oxamate forms a salt bridge with Arg-171 and hydrogen bonds with His-195, Thr-246 and Asn-140. Further structural rearrangement and loop closure, which also brings about another hydrogen bond between oxamate and Arg-109, will increase the rate of fluorescence quenching as well.
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Affiliation(s)
- Huo-Lei Peng
- Department of Biochemistry, Albert Einstein College of Medicine, New
York, NY 10461, USA
| | - Robert Callender
- Department of Biochemistry, Albert Einstein College of Medicine, New
York, NY 10461, USA
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6
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Demidyuk I, Chukhontseva K, Kostrov S. Glutamyl Endopeptidases: The Puzzle of Substrate Specificity. Acta Naturae 2017; 9:17-33. [PMID: 28740724 PMCID: PMC5508998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Indexed: 11/24/2022] Open
Abstract
Glutamyl endopeptidases (GEPases) are chymotrypsin-like enzymes that preferentially cleave the peptide bonds of the α-carboxyl groups of glutamic acid. Despite the many years of research, the structural determinants underlying the strong substrate specificity of GEPases still remain unclear. In this review, data concerning the molecular mechanisms that determine the substrate preference of GEPases is generalized. In addition, the biological functions of and modern trends in the research into these enzymes are outlined.
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Affiliation(s)
- I.V. Demidyuk
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq., 2, Moscow, 123182, Russia
| | - K.N. Chukhontseva
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq., 2, Moscow, 123182, Russia
| | - S.V. Kostrov
- Institute of Molecular Genetics, Russian Academy of Sciences, Kurchatov Sq., 2, Moscow, 123182, Russia
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7
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Świderek K, Tuñón I, Martí S, Moliner V. Protein Conformational Landscapes and Catalysis. Influence of Active Site Conformations in the Reaction Catalyzed by L-Lactate Dehydrogenase. ACS Catal 2015; 5:1172-1185. [PMID: 25705562 DOI: 10.1021/cs501704f] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In the last decade L-Lactate Dehydrogenase (LDH) has become an extremely useful marker in both clinical diagnosis and in monitoring the course of many human diseases. It has been assumed from the 80s that the full catalytic process of LDH starts with the binding of the cofactor and the substrate followed by the enclosure of the active site by a mobile loop of the protein before the reaction to take place. In this paper we show that the chemical step of the LDH catalyzed reaction can proceed within the open loop conformation, and the different reactivity of the different protein conformations would be in agreement with the broad range of rate constants measured in single molecule spectrometry studies. Starting from a recently solved X-ray diffraction structure that presented an open loop conformation in two of the four chains of the tetramer, QM/MM free energy surfaces have been obtained at different levels of theory. Depending on the level of theory used to describe the electronic structure, the free energy barrier for the transformation of pyruvate into lactate with the open conformation of the protein varies between 12.9 and 16.3 kcal/mol, after quantizing the vibrations and adding the contributions of recrossing and tunneling effects. These values are very close to the experimentally deduced one (14.2 kcal·mol-1) and ~2 kcal·mol-1 smaller than the ones obtained with the closed loop conformer. Calculation of primary KIEs and IR spectra in both protein conformations are also consistent with our hypothesis and in agreement with experimental data. Our calculations suggest that the closure of the active site is mainly required for the inverse process; the oxidation of lactate to pyruvate. According to this hypothesis H4 type LDH enzyme molecules, where it has been propose that lactate is transformed into pyruvate, should have a better ability to close the mobile loop than the M4 type LDH molecules.
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Affiliation(s)
- Katarzyna Świderek
- Departament
de Química Física, Universitat de València, 46100 Burjassot, Spain
- Institute
of Applied Radiation Chemistry, Lodz University of Technology, 90-924 Lodz, Poland
| | - Iñaki Tuñón
- Departament
de Química Física, Universitat de València, 46100 Burjassot, Spain
| | - Sergio Martí
- Departament
de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain
| | - Vicent Moliner
- Departament
de Química Física i Analítica, Universitat Jaume I, 12071 Castelló, Spain
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8
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Ferrer S, Tuñón I, Moliner V, Williams IH. Theoretical site-directed mutagenesis: Asp168Ala mutant of lactate dehydrogenase. J R Soc Interface 2009; 5 Suppl 3:S217-24. [PMID: 18682365 DOI: 10.1098/rsif.2008.0211.focus] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Molecular simulations based on the use of hybrid quantum mechanics/molecular mechanics methods are able to provide detailed information about the complex enzymatic reactions and the consequences of specific mutations on the activity of the enzyme. In this work, the reduction of pyruvate to lactate catalysed by wild-type and Asp168Ala mutant lactate dehydrogenase (LDH) has been studied by means of simulations using a very flexible molecular model consisting of the full tetramer of the enzyme, together with the cofactor NADH, the substrate and solvent water molecules. Our results indicate that the Asp168Ala mutation provokes a shift in the pKa value of Glu199 that becomes unprotonated at neutral pH in the mutant enzyme. This change compensates the loss of the negative charge of Asp168, rendering a still active enzyme. Thus, our methodology gives a calculated barrier height for the Asp168Ala mutant 3 kcal mol-1 higher than that for wild-type LDH, which is in very good agreement with the experiment. The computed potential energy surfaces reveal the reaction pathways and transition structures for the wild-type and mutant enzymes. Hydride transfer is less advanced and the proton transfer is more advanced in the Asp168Ala mutant than in the wild type. This approach provides a very powerful tool for the analysis of the roles of key active-site residues.
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Affiliation(s)
- Silvia Ferrer
- Departamento de Química Física, Universidad de Valencia, Burjassot, Valencia, Spain
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9
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Lai CJ, Wu JC. A simple kinetic method for rapid mechanistic analysis of reversible enzyme inhibitors. Assay Drug Dev Technol 2004; 1:527-35. [PMID: 15090249 DOI: 10.1089/154065803322302781] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
A simple diagnostic method for mechanistic analysis of reversible enzyme inhibitors is presented. The method involves simple experimentation to determine how the inhibition by a reversible inhibitor changes in response to the substrate concentration varied in the assay. Four types of inhibitors are categorized based on their kinetic characteristic: (1) competitive or mutually exclusive inhibitors that compete with the substrate for the enzyme; (2) noncompetitive inhibitors that are independent of the substrate for binding to the enzyme; (3) antagonistic inhibitors where the binding affinity of the inhibitor is partially reduced by the substrate binding to the enzyme; and (4) synergistic inhibitors where inhibitor binding is enhanced by substrate binding. An equation was derived for data fitting and subsequent determination of inhibitor binding mode. The method was evaluated in three model enzyme systems, i.e., PK, adenylate kinase, and LDH, with known inhibitors. The method was also used to characterize a large number of unknown Csp3 inhibitors identified from HTS of a compound library consisting of 120,000 distinct chemical entities, a field test that validated the utility of the method. Among 76 Csp3 inhibitors analyzed, 70 were found to be non-mutually exclusive inhibitors, suggesting the existence of an allosteric site(s) in Csp3 for effective inhibition. The implication of this observation is discussed.
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10
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Cortés A, Cascante M, Cárdenas ML, Cornish-Bowden A. Relationships between inhibition constants, inhibitor concentrations for 50% inhibition and types of inhibition: new ways of analysing data. Biochem J 2001; 357:263-8. [PMID: 11415458 PMCID: PMC1221950 DOI: 10.1042/0264-6021:3570263] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The concentration of an inhibitor that decreases the rate of an enzyme-catalysed reaction by 50%, symbolized i(0.5), is often used in pharmacological studies to characterize inhibitors. It can be estimated from the common inhibition plots used in biochemistry by means of the fact that the extrapolated inhibitor concentration at which the rate becomes infinite is equal to -i(0.5). This method is, in principle, more accurate than comparing the rates at various different inhibitor concentrations, and inferring the value of i(0.5) by interpolation. Its reciprocal, 1/i(0.5), is linearly dependent on v(0)/V, the uninhibited rate divided by the limiting rate, and the extrapolated value of v(0)/V at which 1/i(0.5) is zero allows the type of inhibition to be characterized: this value is 1 if the inhibition is strictly competitive; greater than 1 if the inhibition is mixed with a predominantly competitive component; infinite (i.e. 1/i(0.5) does not vary with v(0)/V) if the inhibition is pure non-competitive (i.e. mixed with competitive and uncompetitive components equal); negative if the inhibition is mixed with a predominantly uncompetitive component; and zero if it is strictly uncompetitive. The type of analysis proposed has been tested experimentally by examining inhibition of lactate dehydrogenase by oxalate (an uncompetitive inhibitor with respect to pyruvate) and oxamate (a competitive inhibitor with respect to pyruvate), and of cytosolic malate dehydrogenase by hydroxymalonate (a mixed inhibitor with respect to oxaloacetate). In all cases there is excellent agreement between theory and experiment.
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Affiliation(s)
- A Cortés
- Departament de Bioquímica i Biologia Molecular, Facultat de Química, Universitat de Barcelona, Martí i Franqués 1, 08028 Barcelona, Catalunya, Spain
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11
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Coenzymes of Oxidation—Reduction Reactions. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50018-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Alvarez JA, Gelpí JL, Johnsen K, Bernard N, Delcour J, Clarke AR, Holbrook JJ, Cortés A. D-2-hydroxy-4-methylvalerate dehydrogenase from Lactobacillus delbrueckii subsp. bulgaricus. I. Kinetic mechanism and pH dependence of kinetic parameters, coenzyme binding and substrate inhibition. EUROPEAN JOURNAL OF BIOCHEMISTRY 1997; 244:203-12. [PMID: 9063465 DOI: 10.1111/j.1432-1033.1997.00203.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The steady-state kinetics of D-2-hydroxy-4-methylvalerate dehydrogenase have been studied at pH 8.0 by initial velocity, product inhibition, and dead-end inhibition techniques. The mechanism is rapid-equilibrium ordered in the NAD+ plus D-2-hydroxy-4-methylvalerate direction, and steady-state ordered in the other direction. In both cases coenzyme is the first substrate added and both the E-NADH-D-2-hydroxy-4-methylvalerate and E-NAD+-2-oxo-4-methylvalerate give rise to abortive complexes which cause excess substrate inhibition. Steady-state measurements show that the rate-limiting step in both directions at pH 8.0 is between formation of the enzyme-coenzyme-substrate ternary complex and the release of the first product of the reaction. Transient kinetics combined with primary kinetic deuterium isotope effects show that in the NADH-->NAD+ direction there is a slow, rate-limiting rearrangement of the E-NADH-oxoacid complex while hydride transfer is very fast. The release of NAD+ at pH 8.0 is 200-times faster than Kcat (NADH-->NAD+) whereas the release of NADH is only 5-times faster than Kcat (NAD+-->NADH). The pH dependence of NADH binding depends upon the presence of two ionizable residues with a pKa of about 5.9. The pH dependence of kinetic parameters is explained by a third ionizable residue with pKa values 7.2 (in the E-NADH complex) and < or = 6.4 (in the E-NAD+ complex) which may be the proton donor and acceptor for the chemical reaction. At pH 6.5 the mechanism changes in the NADH-->NAD+ direction to be partly limited by the chemical step with a measured primary kinetic isotope effect of 5.7 and partly by an only slightly faster dissociation of NAD+. In addition the inhibition by excess oxo-4-methylvalerate is more pronounced. The mechanism implies that removing the positive charges created by the two groups which control coenzyme affinity could both enhance the catalytic rate at pH 6.5 and diminish excess substrate inhibition to provide an enzyme better suited to the bulk synthesis of D-2-hydroxyacids.
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Affiliation(s)
- J A Alvarez
- Departament de Bioquímica i Biologia Molecular, Universitat de Barcelona, Spain
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13
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Eszes CM, Sessions RB, Clarke AR, Moreton KM, Holbrook JJ. Removal of substrate inhibition in a lactate dehydrogenase from human muscle by a single residue change. FEBS Lett 1996; 399:193-7. [PMID: 8985143 DOI: 10.1016/s0014-5793(96)01317-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
High concentrations of ketoacid substrates inhibit most natural hydroxyacid dehydrogenases due to the formation of an abortive enzyme-NAD+-ketoacid complex. It was postulated that this substrate inhibition could be eliminated from lactate dehydrogenases if the rate of NAD+ dissociation could be increased. An analysis of the crystal structure of mammalian LDHs showed that the amide of the nicotinamide cofactor formed a water-bridged hydrogen bond to S163. The LDH of Plasmodium falciparum is not inhibited by its substrate and, uniquely, in this enzyme the serine is replaced by a leucine. In the S163L mutant of human LDH-M4 pyruvate inhibition is, indeed, abolished and the enzyme retains high activity. However, the major contribution to this effect comes from a weakening of the interaction of pyruvate with the enzyme-coenzyme complex.
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Affiliation(s)
- C M Eszes
- Molecular Recognition Centre and Department of Biochemistry, School of Medical Sciences, University Walk, Bristol, UK
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14
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Affiliation(s)
- B V Plapp
- Department of Biochemistry, University of Iowa, Iowa City 52242, USA
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15
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el Hawrani AS, Moreton KM, Sessions RB, Clarke AR, Holbrook JJ. Engineering surface loops of proteins--a preferred strategy for obtaining new enzyme function. Trends Biotechnol 1994; 12:207-11. [PMID: 7764905 DOI: 10.1016/0167-7799(94)90084-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A prerequisite for the rational redesign of enzymes is that altering amino acids in an attempt to obtain new biological function does not unexpectedly alter the globular, natural framework of the native protein on which the design is being executed. The results of combinatorial-mutagenesis strategies suggest that random variation of amino acid sequence is most easily tolerated at the solvent-exposed surfaces of a protein. This review analyses effective redesigns of Bacillus stearothermophilus lactate dehydrogenase (bsLDH), in which all residue variations are at solvent-exposed surfaces. The majority of these variations were located within surface loops, which interconnect stable secondary structures traversing the globular core of the protein.
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Affiliation(s)
- A S el Hawrani
- Molecular Recognition Centre, University of Bristol School of Medical Sciences, UK
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Nicholls DJ, Wood IS, Nobbs TJ, Clarke AR, Holbrook JJ, Atkinson T, Scawen MD. Dissecting the contributions of a specific side-chain interaction to folding and catalysis of Bacillus stearothermophilus lactate dehydrogenase. EUROPEAN JOURNAL OF BIOCHEMISTRY 1993; 212:447-55. [PMID: 8444183 DOI: 10.1111/j.1432-1033.1993.tb17681.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
X-ray crystallography predicts hydrogen-bonding interactions between the side chains of Thr198 and two other amino acid residues, Glu194 (adjacent to the catalytic His195) and Ser318 (on the alpha-H helix which rearranges on substrate binding). In order to investigate the contribution of this conserved amino acid residue, Thr198, two mutants of Bacillus stearothermophilus lactate dehydrogenase were created (Val198 and Ile198). The steady-state kinetic parameters for both mutant enzymes were very similar with increased substrate Km and reduced kcat when compared with the wild-type enzyme. The mutation Val198 allowed non-productive binding of pyruvate to the unprotonated form of His195. Steady-state kinetic parameters determined for the Val198 mutant enzyme in high solvent viscosity suggested both an altered rate-limiting step in catalysis and implicated Thr198 in allosteric activation by the effector fructose 1,6-bisphosphate (Fru1,6P2). A shift in the Fru1,6P2 activation constant for the Val198 mutant enzyme suggested that Thr198 stabilises the catalytically competent (Fru1,6P2-activated) form of the enzyme by 6.6 kJ/mol. However, Thr198 was not important for maintaining the thermal stability of the Fru1,6P2-activated form. Equilibrium unfolding in guanidinium chloride indicated that Thr198 contributes 17.2 kJ/mol subunits towards the tertiary structural stability. The results emphasise the importance of the side chain-hydroxyl group of Thr198 which is required for (a) productive substrate binding, (b) allosteric activation and (c) protein conformational stability. The characteristics of the B. stearothermophilus lactate dehydrogenase mutations reported here were significantly different from those of the same mutations made in the corresponding position of the analogous enzyme Thermus flavus malate dehydrogenase [Nishiyama, M., Shimada, K., Horinouchi, S., & Beppu, T. (1991) J. Biol. Chem. 266, 14294-14299].
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Affiliation(s)
- D J Nicholls
- Division of Biotechnology, Centre for Applied Microbiology and Research, Porton Down, Salisbury, England
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