1
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Kuehm OP, Hayden JA, Bearne SL. A Phenylboronic Acid-Based Transition State Analogue Yields Nanomolar Inhibition of Mandelate Racemase. Biochemistry 2023. [PMID: 37285384 DOI: 10.1021/acs.biochem.3c00143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Mandelate racemase (MR) catalyzes the Mg2+-dependent interconversion of (R)- and (S)-mandelate by stabilizing the altered substrate in the transition state (TS) by ∼26 kcal/mol. The enzyme has been employed as a model to explore the limits to which the free energy of TS stabilization may be captured by TS analogues to effect strong binding. Herein, we determined the thermodynamic parameters accompanying binding of a series of bromo-, chloro-, and fluoro-substituted phenylboronic acids (PBAs) by MR and found that binding was predominately driven by favorable entropy changes. 3,4-Dichloro-PBA was discovered to be the most potent inhibitor yet identified for MR, binding with a Kdapp value of 11 ± 2 nM and exceeding the binding of the substrate by ∼72,000-fold. The ΔCp value accompanying binding (-488 ± 18 cal·mol-1 K-1) suggested that dispersion forces contribute significantly to the binding. The pH-dependence of the inhibition revealed that MR preferentially binds the anionic, tetrahedral form of 3,4-dichloro-PBA with a pH-independent Ki value of 5.7 ± 0.5 nM, which was consistent with the observed upfield shift of the 11B NMR signal. The linear free energy relationship between log(kcat/Km) and log(1/Ki) for wild-type and 11 MR variants binding 3,4-dichloro-PBA had a slope of 0.8 ± 0.2, indicating that MR recognizes the inhibitor as an analogue of the TS. Hence, halogen substitution may be utilized to capture additional free energy of TS stabilization arising from dispersion forces to enhance the binding of boronic acid inhibitors by MR.
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Affiliation(s)
- Oliver P Kuehm
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Joshua A Hayden
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
- Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada
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2
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Floros KV, Chawla AT, Johnson-Berro MO, Khatri R, Stamatouli AM, Boikos SA, Dozmorov MG, Cowart LA, Faber AC. MYCN upregulates the transsulfuration pathway to suppress the ferroptotic vulnerability in MYCN-amplified neuroblastoma. Cell Stress 2022; 6:21-29. [PMID: 35174317 PMCID: PMC8802432 DOI: 10.15698/cst2022.02.264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/04/2021] [Accepted: 12/06/2021] [Indexed: 11/24/2022] Open
Abstract
Ferroptosis is an iron-dependent, oxidative form of cell death that is countered mainly by glutathione peroxidase 4 (GPX4) and the production of glutathione (GSH), which is formed from cysteine. The identification of the cancers that may benefit from pharmacological ferroptotic induction is just emerging. We recently demonstrated that inducing ferroptosis genetically or pharmacologically in MYCN-amplified neuroblastoma (NB) is a novel and effective way to kill these cells. MYCN increases iron metabolism and subsequent hydroxyl radicals through increased expression of the transferrin receptor 1 (TfR1) and low levels of the ferroportin receptor. To counter increased hydroxyl radicals, MYCN binds to the promoter of SLC3A2 (solute carrier family 3 member 2). SLC3A2 is a subunit of system Xc-, which is the cysteine-glutamate antiporter that exports glutamate and imports cystine. Cystine is converted to cysteine intracellularly. Here, we investigated other ways MYCN may increase cysteine levels. By performing metabolomics in a syngeneic NB cell line either expressing MYCN or GFP, we demonstrate that the transsulfuration pathway is activated by MYCN. Furthermore, we demonstrate that MYCN-amplified NB cell lines and tumors have higher levels of cystathionine beta-synthase (CBS), the rate-limiting enzyme in transsulfuration, which leads to higher levels of the thioether cystathionine (R-S-(2-amino-2-carboxyethyl)-l-homocysteine). In addition, MYCN-amplified NB tumors have high levels of methylthioadenosine phosphorylase (MTAP), an enzyme that helps salvage methionine following polyamine metabolism. MYCN directly binds to the promoter of MTAP. We propose that MYCN orchestrates both enhanced cystine uptake and enhanced activity of the transsulfuration pathway to counteract increased reactive oxygen species (ROS) from iron-induced Fenton reactions, ultimately contributing to a ferroptosis vulnerability in MYCN-amplified neuroblastoma.
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Affiliation(s)
- Konstantinos V. Floros
- Department of Oral and Craniofacial Molecular Biology, Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Ayesha T. Chawla
- Department of Oral and Craniofacial Molecular Biology, Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Mia O. Johnson-Berro
- Department of Oral and Craniofacial Molecular Biology, Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Rishabh Khatri
- Department of Oral and Craniofacial Molecular Biology, Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Angeliki M. Stamatouli
- Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Sosipatros A. Boikos
- Division of Hematology, Oncology and Palliative Care, Virginia Commonwealth University and Massey Cancer Center, Richmond, VA, USA
| | - Mikhail G. Dozmorov
- Department of Biostatistics, Virginia Commonwealth University, Richmond, VA, USA
| | - L. Ashley Cowart
- Department of Biochemistry and Molecular Biology and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
- Hunter Holmes McGuire Veteran’s Affairs Medical Center, Richmond, VA, USA
| | - Anthony C. Faber
- Department of Oral and Craniofacial Molecular Biology, Philips Institute for Oral Health Research, VCU School of Dentistry and Massey Cancer Center, Virginia Commonwealth University, Richmond, VA, USA
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3
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Huai Z, Yang H, Sun Z. Binding thermodynamics and interaction patterns of human purine nucleoside phosphorylase-inhibitor complexes from extensive free energy calculations. J Comput Aided Mol Des 2021; 35:643-656. [PMID: 33759016 DOI: 10.1007/s10822-021-00382-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 03/13/2021] [Indexed: 11/29/2022]
Abstract
Human purine nucleoside phosphorylase (hPNP) plays a significant role in the catabolism of deoxyguanosine. The trimeric protein is an important target in the treatment of T-cell cancers and autoimmune disorders. Experimental studies on the inhibition of the hPNP observe that the first ligand bound to one of three subunits effectively inhibits the protein, while the binding of more ligands to the subsequent sites shows negative cooperativities. In this work, we performed extensive end-point and alchemical free energy calculations to determine the binding thermodynamics of the trimeric protein-ligand system. 13 Immucillin inhibitors with experimental results are under calculation. Two widely accepted charge schemes for small molecules including AM1-BCC and RESP are adopted for ligands. The results of RESP are in better agreement with the experimental reference. Further investigations of the interaction networks in the protein-ligand complexes reveal that several residues play significant roles in stabilizing the complex structure. The most commonly observed ones include PHE200, GLU201, MET219, and ASN243. The conformations of the protein in different protein-ligand complexes are observed to be similar. We expect these insights to aid the development of potent drugs targeting hPNP.
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Affiliation(s)
- Zhe Huai
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China
| | - Huaiyu Yang
- College of Engineering, Hebei Normal University, Shijiazhuang, 050024, China
| | - Zhaoxi Sun
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai, 200062, China.
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4
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Lin HY, Chen CY, Lin TC, Yeh LF, Hsieh WC, Gao S, Burnouf PA, Chen BM, Hsieh TJ, Dashnyam P, Kuo YH, Tu Z, Roffler SR, Lin CH. Entropy-driven binding of gut bacterial β-glucuronidase inhibitors ameliorates irinotecan-induced toxicity. Commun Biol 2021; 4:280. [PMID: 33664385 PMCID: PMC7933434 DOI: 10.1038/s42003-021-01815-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 02/08/2021] [Indexed: 12/31/2022] Open
Abstract
Irinotecan inhibits cell proliferation and thus is used for the primary treatment of colorectal cancer. Metabolism of irinotecan involves incorporation of β-glucuronic acid to facilitate excretion. During transit of the glucuronidated product through the gastrointestinal tract, an induced upregulation of gut microbial β-glucuronidase (GUS) activity may cause severe diarrhea and thus force many patients to stop treatment. We herein report the development of uronic isofagomine (UIFG) derivatives that act as general, potent inhibitors of bacterial GUSs, especially those of Escherichia coli and Clostridium perfringens. The best inhibitor, C6-nonyl UIFG, is 23,300-fold more selective for E. coli GUS than for human GUS (Ki = 0.0045 and 105 μM, respectively). Structural evidence indicated that the loss of coordinated water molecules, with the consequent increase in entropy, contributes to the high affinity and selectivity for bacterial GUSs. The inhibitors also effectively reduced irinotecan-induced diarrhea in mice without damaging intestinal epithelial cells.
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Affiliation(s)
- Hsien-Ya Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Chia-Yu Chen
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Ting-Chien Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, Taiwan
| | - Lun-Fu Yeh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Wei-Che Hsieh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Shijay Gao
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | - Bing-Mae Chen
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Tung-Ju Hsieh
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | | | - Yen-Hsi Kuo
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Zhijay Tu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Steve R Roffler
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
| | - Chun-Hung Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
- Department of Chemistry, National Taiwan University, Taipei, Taiwan.
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
- The Genomics Research Center, Academia Sinica, Taipei, Taiwan.
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5
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Harijan RK, Hoff O, Ducati RG, Firestone RS, Hirsch BM, Evans GB, Schramm VL, Tyler PC. Selective Inhibitors of Helicobacter pylori Methylthioadenosine Nucleosidase and Human Methylthioadenosine Phosphorylase. J Med Chem 2019; 62:3286-3296. [PMID: 30860833 PMCID: PMC6635953 DOI: 10.1021/acs.jmedchem.8b01642] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacterial 5'-methylthioadenosine/ S-adenosylhomocysteine nucleosidase (MTAN) hydrolyzes adenine from its substrates to form S-methyl-5-thioribose and S-ribosyl-l-homocysteine. MTANs are involved in quorum sensing, menaquinone synthesis, and 5'-methylthioadenosine recycling to S-adenosylmethionine. Helicobacter pylori uses MTAN in its unusual menaquinone pathway, making H. pylori MTAN a target for antibiotic development. Human 5'-methylthioadenosine phosphorylase (MTAP), a reported anticancer target, catalyzes phosphorolysis of 5'-methylthioadenosine to salvage S-adenosylmethionine. Transition-state analogues designed for HpMTAN and MTAP show significant overlap in specificity. Fifteen unique transition-state analogues are described here and are used to explore inhibitor specificity. Several analogues of HpMTAN bind in the picomolar range while inhibiting human MTAP with orders of magnitude weaker affinity. Structural analysis of HpMTAN shows inhibitors extending through a hydrophobic channel to the protein surface. The more enclosed catalytic sites of human MTAP require the inhibitors to adopt a folded structure, displacing the phosphate nucleophile from the catalytic site.
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Affiliation(s)
- Rajesh K. Harijan
- Department of Biochemistry, Albert Einstein College
of Medicine, New York 10461, New York, United States
| | - Oskar Hoff
- Ferrier Research Institute, Victoria University of
Wellington, Wellington 5040, New Zealand
| | - Rodrigo G. Ducati
- Department of Biochemistry, Albert Einstein College
of Medicine, New York 10461, New York, United States
| | - Ross S. Firestone
- Department of Biochemistry, Albert Einstein College
of Medicine, New York 10461, New York, United States
| | - Brett M. Hirsch
- Department of Biochemistry, Albert Einstein College
of Medicine, New York 10461, New York, United States
| | - Gary B. Evans
- Ferrier Research Institute, Victoria University of
Wellington, Wellington 5040, New Zealand
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College
of Medicine, New York 10461, New York, United States
| | - Peter C. Tyler
- Ferrier Research Institute, Victoria University of
Wellington, Wellington 5040, New Zealand
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6
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Abstract
Transition state theory teaches that chemically stable mimics of enzymatic transition states will bind tightly to their cognate enzymes. Kinetic isotope effects combined with computational quantum chemistry provides enzymatic transition state information with sufficient fidelity to design transition state analogues. Examples are selected from various stages of drug development to demonstrate the application of transition state theory, inhibitor design, physicochemical characterization of transition state analogues, and their progress in drug development.
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Affiliation(s)
- Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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7
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Lisi GP, Currier AA, Loria JP. Glutamine Hydrolysis by Imidazole Glycerol Phosphate Synthase Displays Temperature Dependent Allosteric Activation. Front Mol Biosci 2018; 5:4. [PMID: 29468164 PMCID: PMC5808140 DOI: 10.3389/fmolb.2018.00004] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/09/2018] [Indexed: 11/13/2022] Open
Abstract
The enzyme imidazole glycerol phosphate synthase (IGPS) is a model for studies of long-range allosteric regulation in enzymes. Binding of the allosteric effector ligand N'-[5'-phosphoribulosyl)formimino]-5-aminoimidazole-4-carboxamide-ribonucleotide (PRFAR) stimulates millisecond (ms) timescale motions in IGPS that enhance its catalytic function. We studied the effect of temperature on these critical conformational motions and the catalytic mechanism of IGPS from the hyperthermophile Thermatoga maritima in an effort to understand temperature-dependent allostery. Enzyme kinetic and NMR dynamics measurements show that apo and PRFAR-activated IGPS respond differently to changes in temperature. Multiple-quantum Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion experiments performed at 303, 323, and 343 K (30, 50, and 70°C) reveal that millisecond flexibility is enhanced to a higher degree in apo IGPS than in the PRFAR-bound enzyme as the sample temperature is raised. We find that the flexibility of the apo enzyme is nearly identical to that of its PRFAR activated state at 343 K, whereas conformational motions are considerably different between these two forms of the enzyme at room temperature. Arrhenius analyses of these flexible sites show a varied range of activation energies that loosely correlate to allosteric communities identified by computational methods and reflect local changes in dynamics that may facilitate conformational sampling of the active conformation. In addition, kinetic assays indicate that allosteric activation by PRFAR decreases to 65-fold at 343 K, compared to 4,200-fold at 303 K, which mirrors the decreased effect of PRFAR on ms motions relative to the unactivated enzyme. These studies indicate that at the growth temperature of T. maritima, PFRAR is a weaker allosteric activator than it is at room temperature and illustrate that the allosteric mechanism of IGPS is temperature dependent.
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Affiliation(s)
- George P Lisi
- Department of Chemistry, Yale University, New Haven, CT, United States
| | - Allen A Currier
- Department of Chemistry, Yale University, New Haven, CT, United States
| | - J Patrick Loria
- Department of Chemistry, Yale University, New Haven, CT, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, United States
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8
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Bearne SL, St Maurice M. A Paradigm for CH Bond Cleavage: Structural and Functional Aspects of Transition State Stabilization by Mandelate Racemase. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2017; 109:113-160. [PMID: 28683916 DOI: 10.1016/bs.apcsb.2017.04.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Mandelate racemase (MR) from Pseudomonas putida catalyzes the Mg2+-dependent, 1,1-proton transfer reaction that racemizes (R)- and (S)-mandelate. MR shares a partial reaction (i.e., the metal ion-assisted, Brønsted base-catalyzed proton abstraction of the α-proton of carboxylic acid substrates) and structural features ((β/α)7β-barrel and N-terminal α + β capping domains) with a vast group of homologous, yet functionally diverse, enzymes in the enolase superfamily. Mechanistic and structural studies have developed this enzyme into a paradigm for understanding how enzymes such as those of the enolase superfamily overcome kinetic and thermodynamic barriers to catalyze the abstraction of an α-proton from a carbon acid substrate with a relatively high pKa value. Structural studies on MR bound to intermediate/transition state analogues have delineated those structural features that MR uses to stabilize transition states and enhance reaction rates of proton abstraction. Kinetic, site-directed mutagenesis, and structural studies have also revealed that the phenyl ring of the substrate migrates through the hydrophobic cavity within the active site during catalysis and that the Brønsted acid-base catalysts (Lys 166 and His 297) may be utilized as binding determinants for inhibitor recognition. In addition, structural studies on the adduct formed from the irreversible inhibition of MR by 3-hydroxypyruvate revealed that MR can form and deprotonate a Schiff-base with 3-hydroxypyruvate to yield an enol(ate)-aldehyde adduct, suggesting a possible evolutionary link between MR and the Schiff-base forming aldolases. As the archetype of the enolase superfamily, mechanistic and structural studies on MR will continue to enhance our understanding of enzyme catalysis and furnish insights into the evolution of enzyme function.
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9
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Firestone RS, Cameron SA, Karp JM, Arcus VL, Schramm VL. Heat Capacity Changes for Transition-State Analogue Binding and Catalysis with Human 5'-Methylthioadenosine Phosphorylase. ACS Chem Biol 2017; 12:464-473. [PMID: 28026167 PMCID: PMC5462123 DOI: 10.1021/acschembio.6b00885] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Human 5'-methylthioadenosine phosphorylase (MTAP) catalyzes the phosphorolysis of 5'-methylthioadenosine (MTA). Its action regulates cellular MTA and links polyamine synthesis to S-adenosylmethionine (AdoMet) salvage. Transition state analogues with picomolar dissociation constants bind to MTAP in an entropically driven process at physiological temperatures, suggesting increased hydrophobic character or dynamic structure for the complexes. Inhibitor binding exhibits a negative heat capacity change (-ΔCp), and thus the changes in enthalpy and entropy upon binding are strongly temperature-dependent. The ΔCp of inhibitor binding by isothermal titration calorimetry does not follow conventional trends and is contrary to that expected from the hydrophobic effect. Thus, ligands of increasing hydrophobicity bind with increasing values of ΔCp. Crystal structures of MTAP complexed to transition-state analogues MT-DADMe-ImmA, BT-DADMe-ImmA, PrT-ImmA, and a substrate analogue, MT-tubercidin, reveal similar active site contacts and overall protein structural parameters, despite large differences in ΔCp for binding. In addition, ΔCp values are not correlated with Kd values. Temperature dependence of presteady state kinetics revealed the chemical step for the MTAP reaction to have a negative heat capacity for transition state formation (-ΔCp‡). A comparison of the ΔCp‡ for MTAP presteady state chemistry and ΔCp for inhibitor binding revealed those transition-state analogues most structurally and thermodynamically similar to the transition state. Molecular dynamics simulations of MTAP apoenzyme and complexes with MT-DADMe-ImmA and MT-tubercidin show small, but increased dynamic motion in the inhibited complexes. Variable temperature CD spectroscopy studies for MTAP-inhibitor complexes indicate remarkable protein thermal stability (to Tm = 99 °C) in complexes with transition-state analogues.
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Affiliation(s)
- Ross S. Firestone
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Scott A. Cameron
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Jerome M. Karp
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Vickery L. Arcus
- Faculty of Science and Engineering, Department of Biological Science, University of Waikato, Private Bag 3105, Hamilton, New Zealand
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States,Corresponding Author: Phone: 718-430-2813.
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10
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Ben-Shalom IY, Pfeiffer-Marek S, Baringhaus KH, Gohlke H. Efficient Approximation of Ligand Rotational and Translational Entropy Changes upon Binding for Use in MM-PBSA Calculations. J Chem Inf Model 2017; 57:170-189. [DOI: 10.1021/acs.jcim.6b00373] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Ido Y. Ben-Shalom
- Institute
for Pharmaceutical and Medicinal Chemistry, Department of Mathematics
and Natural Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
| | - Stefania Pfeiffer-Marek
- LGCR/Pharmaceutical
Sciences Operations, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, 65926 Frankfurt am Main, Germany
| | - Karl-Heinz Baringhaus
- R&D Resources/Site Direction, Sanofi-Aventis Deutschland GmbH, Industriepark Höchst, 65926 Frankfurt am Main, Germany
| | - Holger Gohlke
- Institute
for Pharmaceutical and Medicinal Chemistry, Department of Mathematics
and Natural Sciences, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany
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11
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Firestone RS, Cameron SA, Tyler PC, Ducati RG, Spitz AZ, Schramm VL. Continuous Fluorescence Assays for Reactions Involving Adenine. Anal Chem 2016; 88:11860-11867. [PMID: 27779859 PMCID: PMC5434977 DOI: 10.1021/acs.analchem.6b03621] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
5'-Methylthioadenosine phosphorylase (MTAP) and 5'-methylthioadenosine nucleosidase (MTAN) catalyze the phosphorolysis and hydrolysis of 5'-methylthioadenosine (MTA), respectively. Both enzymes have low KM values for their substrates. Kinetic assays for these enzymes are challenging, as the ultraviolet absorbance spectra for reactant MTA and product adenine are similar. We report a new assay using 2-amino-5'-methylthioadenosine (2AMTA) as an alternative substrate for MTAP and MTAN enzymes. Hydrolysis or phosphorolysis of 2AMTA forms 2,6-diaminopurine, a fluorescent and easily quantitated product. We kinetically characterize 2AMTA with human MTAP, bacterial MTANs and use 2,6-diaminopurine as a fluorescent substrate for yeast adenine phosphoribosyltransferase. 2AMTA was used as the substrate to kinetically characterize the dissociation constants for three-transition-state analogue inhibitors of MTAP and MTAN. Kinetic values obtained from continuous fluorescent assays with MTA were in good agreement with previously measured literature values, but gave smaller experimental errors. Chemical synthesis from ribose and 2,6-dichloropurine provided crystalline 2AMTA as the oxalate salt. Chemo-enzymatic synthesis from ribose and 2,6-diaminopurine produced 2-amino-S-adenosylmethionine for hydrolytic conversion to 2AMTA. Interaction of 2AMTA with human MTAP was also characterized by pre-steady-state kinetics and by analysis of the crystal structure in a complex with sulfate as a catalytically inert analogue of phosphate. This assay is suitable for inhibitor screening by detection of fluorescent product, for quantitative analysis of hits by rapid and accurate measurement of inhibition constants in continuous assays, and pre-steady-state kinetic analysis of the target enzymes.
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Affiliation(s)
- Ross S. Firestone
- Department of Biochemistry, Albert Einstein College of
Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Scott A. Cameron
- Department of Biochemistry, Albert Einstein College of
Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Peter C. Tyler
- The Ferrier Research Institute, Victoria University of
Wellington, Lower Hutt, Wellington 6140, New Zealand
| | - Rodrigo G. Ducati
- Department of Biochemistry, Albert Einstein College of
Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Adam Z. Spitz
- Department of Biochemistry, Albert Einstein College of
Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Vern L. Schramm
- Department of Biochemistry, Albert Einstein College of
Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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12
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Arcus VL, Prentice EJ, Hobbs JK, Mulholland AJ, Van der Kamp MW, Pudney CR, Parker EJ, Schipper LA. On the Temperature Dependence of Enzyme-Catalyzed Rates. Biochemistry 2016; 55:1681-8. [DOI: 10.1021/acs.biochem.5b01094] [Citation(s) in RCA: 175] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Vickery L. Arcus
- School
of Science, University of Waikato, Hamilton 3240, New Zealand
| | - Erica J. Prentice
- School
of Science, University of Waikato, Hamilton 3240, New Zealand
| | - Joanne K. Hobbs
- School
of Science, University of Waikato, Hamilton 3240, New Zealand
| | | | | | - Christopher R. Pudney
- Department
of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, United Kingdom
| | - Emily J. Parker
- Biomolecular
Interaction Centre and Department of Chemistry, University of Canterbury, Christchurch 8041, New Zealand
| | - Louis A. Schipper
- School
of Science, University of Waikato, Hamilton 3240, New Zealand
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13
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Nagar M, Bearne SL. An additional role for the Brønsted acid-base catalysts of mandelate racemase in transition state stabilization. Biochemistry 2015; 54:6743-52. [PMID: 26480244 DOI: 10.1021/acs.biochem.5b00982] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mandelate racemase (MR) catalyzes the interconversion of the enantiomers of mandelate and serves as a paradigm for understanding the enzyme-catalyzed abstraction of an α-proton from a carbon acid substrate with a high pKa. The enzyme utilizes a two-base mechanism with Lys 166 and His 297 acting as Brønsted acid and base catalysts, respectively, in the R → S reaction direction. In the S → R reaction direction, their roles are reversed. Using isothermal titration calorimetry (ITC), MR is shown to bind the intermediate/transition state (TS) analogue inhibitor benzohydroxamate (BzH) in an entropy-driven process with a value of ΔCp equal to -358 ± 3 cal mol(-1) K(-1), consistent with an increased number of hydrophobic interactions. However, MR binds BzH with an affinity that is ∼2 orders of magnitude greater than that predicted solely on the basis of hydrophobic interactions [St. Maurice, M., and Bearne, S. L. (2004) Biochemistry 43, 2524], suggesting that additional specific interactions contribute to binding. To test the hypothesis that cation-π/NH-π interactions between the side chains of Lys 166 and His 297 and the aromatic ring and/or the hydroxamate/hydroximate moiety of BzH contribute to the binding of BzH, site-directed mutagenesis was used to generate the MR variants K166M, K166C, H297N, and K166M/H297N and their binding affinity for various ligands determined using ITC. Comparison of the binding affinities of these MR variants with the intermediate/TS analogues BzH and cyclohexanecarbohydroxamate revealed that cation-π/NH-π interactions between His 297 and the hydroxamate/hydroximate moiety and the phenyl ring of BzH contribute approximately 0.26 and 0.91 kcal/mol to binding, respectively, while interactions with Lys 166 contribute approximately 1.74 and 1.74 kcal/mol, respectively. Similarly, comparison of the binding affinities of these mutants with substrate analogues revealed that Lys 166 contributes >2.93 kcal/mol to the binding of (R)-atrolactate, and His 297 contributes 2.46 kcal/mol to the binding of (S)-atrolactate. These results are consistent with Lys 166 and His 297 playing dual roles in catalysis: they act as Brønsted acid-base catalysts, and they stabilize both the enolate moiety and phenyl ring of the altered substrate in the TS.
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Affiliation(s)
- Mitesh Nagar
- Department of Biochemistry and Molecular Biology, Dalhousie University , Halifax, NS B3H 4R2, Canada
| | - Stephen L Bearne
- Department of Biochemistry and Molecular Biology, Dalhousie University , Halifax, NS B3H 4R2, Canada.,Department of Chemistry, Dalhousie University , Halifax, NS B3H 4R2, Canada
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14
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Li HJ, Lai CT, Pan P, Yu W, Liu N, Bommineni GR, Garcia-Diaz M, Simmerling C, Tonge PJ. A structural and energetic model for the slow-onset inhibition of the Mycobacterium tuberculosis enoyl-ACP reductase InhA. ACS Chem Biol 2014; 9:986-93. [PMID: 24527857 PMCID: PMC4004265 DOI: 10.1021/cb400896g] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/14/2014] [Indexed: 01/01/2023]
Abstract
Slow-onset enzyme inhibitors are of great interest for drug discovery programs since the slow dissociation of the inhibitor from the drug-target complex results in sustained target occupancy leading to improved pharmacodynamics. However, the structural basis for slow-onset inhibition is often not fully understood, hindering the development of structure-kinetic relationships and the rational optimization of drug-target residence time. Previously we demonstrated that slow-onset inhibition of the Mycobacterium tuberculosis enoyl-ACP reductase InhA correlated with motions of a substrate-binding loop (SBL) near the active site. In the present work, X-ray crystallography and molecular dynamics simulations have been used to map the structural and energetic changes of the SBL that occur upon enzyme inhibition. Helix-6 within the SBL adopts an open conformation when the inhibitor structure or binding kinetics is substrate-like. In contrast, slow-onset inhibition results in large-scale local refolding in which helix-6 adopts a closed conformation not normally populated during substrate turnover. The open and closed conformations of helix-6 are hypothesized to represent the EI and EI* states on the two-step induced-fit reaction coordinate for enzyme inhibition. These two states were used as the end points for nudged elastic band molecular dynamics simulations resulting in two-dimensional potential energy profiles that reveal the barrier between EI and EI*, thus rationalizing the binding kinetics observed with different inhibitors. Our findings indicate that the structural basis for slow-onset kinetics can be understood once the structures of both EI and EI* have been identified, thus providing a starting point for the rational control of enzyme-inhibitor binding kinetics.
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Affiliation(s)
- Huei-Jiun Li
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Cheng-Tsung Lai
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Pan Pan
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Weixuan Yu
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Nina Liu
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Gopal R. Bommineni
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Miguel Garcia-Diaz
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Carlos Simmerling
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
| | - Peter J. Tonge
- Institute for Chemical
Biology and Drug Discovery, Laufer Center for Physical and
Quantitative Biology and Department of Chemistry, Graduate Program in Biochemistry
and Structural Biology, and Department of Pharmacological Sciences, Stony Brook University, Stony Brook, New York 11794, United States
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15
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Wang S, Thomas K, Schramm VL. Catalytic site cooperativity in dimeric methylthioadenosine nucleosidase. Biochemistry 2014; 53:1527-35. [PMID: 24502544 PMCID: PMC3977580 DOI: 10.1021/bi401589n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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5′-Methylthioadenosine/S-adenosylhomocysteine
nucleosidases (MTANs) are bacterial enzymes that catalyze hydrolysis
of the N-ribosidic bonds of 5′-methylthioadenosine
(MTA) and S-adenosylhomocysteine (SAH) to form adenine
and 5-thioribosyl groups. MTANs are involved in AI-1 and AI-2 bacterial
quorum sensing and the unusual futalosine-based menaquinone synthetic
pathway in Streptomyces,Helicobacter, and Campylobacter species. Crystal structures show MTANs to be homodimers with two
catalytic sites near the dimer interface. Here, we explore the cooperative
ligand interactions in the homodimer of Staphylococcus
aureus MTAN (SaMTAN). Kinetic analysis
indicated negative catalytic cooperativity. Titration of SaMTAN with the transition-state analogue MT-DADMe-ImmA gave unequal
catalytic site binding, consistent with negative binding cooperativity.
Thermodynamics of MT-DADMe-ImmA binding also gave negative cooperativity,
where the first site had different enthalpic and entropic properties
than the second site. Cysteine reactivity in a single-cysteine catalytic
site loop construct of SaMTAN is reactive in native
enzyme, less reactive when inhibitor is bound to one subunit, and
nonreactive upon saturation with inhibitor. A fusion peptide heterodimer
construct with one inactive subunit (E173Q) and one native subunit
gave 25% of native SaMTAN activity, similar to native SaMTAN with MT-DADMe-ImmA at one catalytic site. Pre-steady-state
kinetics showed fast chemistry at one catalytic site, consistent with
slow adenine release before catalysis occurs at the second catalytic
site. The results support the two catalytic sites acting sequentially,
with negative cooperativity and product release being linked to motion
of a catalytic site loop contributed by the neighboring subunit.
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Affiliation(s)
- Shanzhi Wang
- Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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16
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Hobbs JK, Jiao W, Easter AD, Parker EJ, Schipper LA, Arcus VL. Change in heat capacity for enzyme catalysis determines temperature dependence of enzyme catalyzed rates. ACS Chem Biol 2013; 8:2388-93. [PMID: 24015933 DOI: 10.1021/cb4005029] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The increase in enzymatic rates with temperature up to an optimum temperature (Topt) is widely attributed to classical Arrhenius behavior, with the decrease in enzymatic rates above Topt ascribed to protein denaturation and/or aggregation. This account persists despite many investigators noting that denaturation is insufficient to explain the decline in enzymatic rates above Topt. Here we show that it is the change in heat capacity associated with enzyme catalysis (ΔC(‡)p) and its effect on the temperature dependence of ΔG(‡) that determines the temperature dependence of enzyme activity. Through mutagenesis, we demonstrate that the Topt of an enzyme is correlated with ΔC(‡)p and that changes to ΔC(‡)p are sufficient to change Topt without affecting the catalytic rate. Furthermore, using X-ray crystallography and molecular dynamics simulations we reveal the molecular details underpinning these changes in ΔC(‡)p. The influence of ΔC(‡)p on enzymatic rates has implications for the temperature dependence of biological rates from enzymes to ecosystems.
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Affiliation(s)
- Joanne K. Hobbs
- Department
of Biological Sciences, Faculty of Science and Engineering, University of Waikato, Hamilton 3240, New Zealand
| | - Wanting Jiao
- Biomolecular
Interaction Centre and Department of Chemistry, University of Canterbury, Christchurch 8041, New Zealand
| | - Ashley D. Easter
- Department
of Biological Sciences, Faculty of Science and Engineering, University of Waikato, Hamilton 3240, New Zealand
| | - Emily J. Parker
- Biomolecular
Interaction Centre and Department of Chemistry, University of Canterbury, Christchurch 8041, New Zealand
| | - Louis A. Schipper
- Department
of Earth and Ocean Sciences, Faculty of Science and Engineering, University of Waikato, Hamilton 3240, New Zealand
| | - Vickery L. Arcus
- Department
of Biological Sciences, Faculty of Science and Engineering, University of Waikato, Hamilton 3240, New Zealand
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17
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Guan R, Tyler PC, Evans GB, Schramm VL. Thermodynamic analysis of transition-state features in picomolar inhibitors of human 5'-methylthioadenosine phosphorylase. Biochemistry 2013; 52:8313-22. [PMID: 24148083 DOI: 10.1021/bi401188w] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Human 5'-methylthioadenosine phosphorylase (MTAP) is solely responsible for 5'-methylthioadenosine (MTA) metabolism to permit S-adenosylmethionine salvage. Transition-state (TS) analogues of MTAP are in development as anticancer candidates. TS analogues of MTAP incorporate a cationic nitrogen and a protonated 9-deazaadenine leaving group, which are mimics of the ribocation transition state. MT-ImmA and MT-DADMe-ImmA are two examples of these TS analogues. Thermodynamic analysis of MTA, inhibitor, and phosphate binding reveals the cationic nitrogen to provide -2.6 and -3.6 kcal/mol binding free energy for MT-ImmA and MT-DADMe-ImmA, respectively. The protonated deazaadenine provides an additional -1.3 (MT-ImmA) to -1.7 kcal/mol (MT-DADMe-ImmA). MT-DADMe-ImmA is a better match in TS geometry than MT-ImmA and is thermodynamically favored. Binding of TS analogues to the MTAP/phosphate complex is fully entropic, in contrast to TS analogue binding to the related human purine nucleoside phosphorylase/phosphate complex, which is fully enthalpic (Guan, R., Ho, M. C., Brenowitz, M., Tyler, P. C., Evans, G. B., Almo, S. C., and Schramm, V. L. (2011) Biochemistry 50, 10408-10417). The binding thermodynamics of phosphate or TS analogues alone to MTAP are fully dominated by enthalpy. Phosphate anchored in the catalytic site forms an ion pair with the cationic TS analogue to cause stabilization of the enzyme structure in the ternary complex. The ternary-induced conformational changes convert the individual enthalpic binding energies to entropy, resulting in a presumed shift of the protein architecture toward the transition state. Formation of the ternary TS analogue complex with MTAP induces a remarkable increase in thermal stability (ΔTm 28 °C). The enthalpic, entropic, and protein-stability features of TS analogue binding to human MTAP are resolved in these studies.
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Affiliation(s)
- Rong Guan
- From the Department of Biochemistry, Albert Einstein College of Medicine, Yeshiva University , 1300 Morris Park Avenue, Bronx, New York 10461, United States
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18
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Mishra V, Ronning DR. Crystal structures of the Helicobacter pylori MTAN enzyme reveal specific interactions between S-adenosylhomocysteine and the 5'-alkylthio binding subsite. Biochemistry 2012; 51:9763-72. [PMID: 23148563 DOI: 10.1021/bi301221k] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The bacterial 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) enzyme is a multifunctional enzyme that catalyzes the hydrolysis of the N-ribosidic bond of at least four different adenosine-based metabolites: S-adenosylhomocysteine (SAH), 5'-methylthioadenosine (MTA), 5'-deoxyadenosine (5'-DOA), and 6-amino-6-deoxyfutalosine. These activities place the enzyme at the hub of seven fundamental bacterial metabolic pathways: S-adenosylmethionine (SAM) utilization, polyamine biosynthesis, the purine salvage pathway, the methionine salvage pathway, the SAM radical pathways, autoinducer-2 biosynthesis, and menaquinone biosynthesis. The last pathway makes MTAN essential for Helicobacter pylori viability. Although structures of various bacterial and plant MTANs have been described, the interactions between the homocysteine moiety of SAH and the 5'-alkylthiol binding site of MTAN have never been resolved. We have determined crystal structures of an inactive mutant form of H. pylori MTAN bound to MTA and SAH to 1.63 and 1.20 Å, respectively. The active form of MTAN was also crystallized in the presence of SAH, allowing the determination of the structure of a ternary enzyme-product complex resolved at 1.50 Å. These structures identify interactions between the homocysteine moiety and the 5'-alkylthiol binding site of the enzyme. This information can be leveraged for the development of species-specific MTAN inhibitors that prevent the growth of H. pylori.
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Affiliation(s)
- Vidhi Mishra
- Department of Chemistry, University of Toledo, Toledo, OH 43606, USA
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19
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King NM, Prabu-Jeyabalan M, Bandaranayake RM, Nalam MNL, Nalivaika EA, Özen A, Haliloǧlu T, Yılmaz NK, Schiffer CA. Extreme entropy-enthalpy compensation in a drug-resistant variant of HIV-1 protease. ACS Chem Biol 2012; 7:1536-46. [PMID: 22712830 DOI: 10.1021/cb300191k] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The development of HIV-1 protease inhibitors has been the historic paradigm of rational structure-based drug design, where structural and thermodynamic analyses have assisted in the discovery of novel inhibitors. While the total enthalpy and entropy change upon binding determine the affinity, often the thermodynamics are considered in terms of inhibitor properties only. In the current study, profound changes are observed in the binding thermodynamics of a drug-resistant variant compared to wild-type HIV-1 protease, irrespective of the inhibitor bound. This variant (Flap+) has a combination of flap and active site mutations and exhibits extremely large entropy-enthalpy compensation compared to wild-type protease, 5-15 kcal/mol, while losing only 1-3 kcal/mol in total binding free energy for any of six FDA-approved inhibitors. Although entropy-enthalpy compensation has been previously observed for a variety of systems, never have changes of this magnitude been reported. The co-crystal structures of Flap+ protease with four of the inhibitors were determined and compared with complexes of both the wild-type protease and another drug-resistant variant that does not exhibit this energetic compensation. Structural changes conserved across the Flap+ complexes, which are more pronounced for the flaps covering the active site, likely contribute to the thermodynamic compensation. The finding that drug-resistant mutations can profoundly modulate the relative thermodynamic properties of a therapeutic target independent of the inhibitor presents a new challenge for rational drug design.
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Affiliation(s)
- Nancy M. King
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Moses Prabu-Jeyabalan
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Rajintha M. Bandaranayake
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Madhavi N. L. Nalam
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Ellen A. Nalivaika
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Ayşegül Özen
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Türkan Haliloǧlu
- Polymer Research Center and Department
of Chemical Engineering, Bogazici University, TR-34342, Bebek, Istanbul, Turkey
| | - Neşe Kurt Yılmaz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
| | - Celia A. Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation
Street, Worcester, Massachusetts 01605, United States
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20
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Thomas K, Haapalainen AM, Burgos ES, Evans GB, Tyler PC, Gulab S, Guan R, Schramm VL. Femtomolar inhibitors bind to 5'-methylthioadenosine nucleosidases with favorable enthalpy and entropy. Biochemistry 2012; 51:7541-50. [PMID: 22931458 DOI: 10.1021/bi3009938] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
5'-Methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) catalyzes the hydrolytic cleavage of adenine from methylthioadenosine (MTA). Inhibitor design and synthesis informed by transition state analysis have developed femtomolar inhibitors for MTANs, among the most powerful known noncovalent enzyme inhibitors. Thermodynamic analyses of the inhibitor binding reveals a combination of highly favorable contributions from enthalpic (-24.7 to -4.0 kcal mol(-1)) and entropic (-10.0 to 6.4 kcal mol(-1)) interactions. Inhibitor binding to similar MTANs from different bacterial species gave distinct energetic contributions from similar catalytic sites. Thus, binding of four transition state analogues to EcMTAN and SeMTAN is driven primarily by enthalpy, while binding to VcMTAN is driven primarily by entropy. Human MTA phosphorylase (hMTAP) has a transition state structure closely related to that of the bacterial MTANs, and it binds tightly to some of the same transition state analogues. However, the thermodynamic signature of binding of an inhibitor to hMTAP differs completely from that with MTANs. We conclude that factors other than first-sphere catalytic residue contacts contribute to binding of inhibitors because the thermodynamic signature differs between bacterial species of the same enzyme.
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Affiliation(s)
- Keisha Thomas
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA
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