1
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Pedro L, Cross M, Hofmann A, Mak T, Quinn RJ. Development of an HPLC-based guanosine monophosphate kinase assay and application to Plasmodium vivax guanylate kinase. Anal Biochem 2019; 575:63-69. [PMID: 30943378 PMCID: PMC6494078 DOI: 10.1016/j.ab.2019.03.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 03/18/2019] [Accepted: 03/29/2019] [Indexed: 11/12/2022]
Abstract
The development of a high-performance liquid chromatography (HPLC)-based method, for guanosine monophosphate kinase activity assays, is presented. The method uses the intrinsic UV absorption (at 260 nm) of substrates and products of the enzymatic reaction (GMP, ATP, ADP and GDP) to unambiguously determine percent conversion of substrate into product. It uses a commercially available C18 column which can separate reaction samples by elution under isocratic conditions in 12 min per run. The kinetics of the forward reaction catalyzed by Plasmodium vivax guanylate kinase (PvGK), a potential drug target against malaria, was determined. The relative concentrations of the two substrates (GMP and ATP) have a distinct effect on reaction velocity. Kinetic analyses showed the PvGK-catalyzed reaction to be associated with atypical kinetics, where substrate inhibition kinetics and non-Michaelis-Menten (sigmoidal) kinetics were found with respect to GMP and ATP, respectively. Additionally, the method was used in inhibition assays to screen twenty fragment-like compounds. The assays were robust and reproducible, with a signal window of 3.8 and a Z’ factor of 0.6. For the best inhibitor, an IC50 curve was generated. Simple HPLC separation of nucleotides involved in the guanylate kinase reaction. Direct and unambiguous determination of percent conversion of substrate into product. Successful application to Plasmodium vivax guanylate kinase (PvGK) activity studies. Reaction catalyzed by PvGK found to be associated with atypical kinetics. Robust and reproducible inhibition assay for compound screening.
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Affiliation(s)
- Liliana Pedro
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Megan Cross
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Andreas Hofmann
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Tin Mak
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Ronald J Quinn
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia.
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2
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Khan N, Shah PP, Ban D, Trigo-Mouriño P, Carneiro MG, DeLeeuw L, Dean WL, Trent JO, Beverly LJ, Konrad M, Lee D, Sabo TM. Solution structure and functional investigation of human guanylate kinase reveals allosteric networking and a crucial role for the enzyme in cancer. J Biol Chem 2019; 294:11920-11933. [PMID: 31201273 DOI: 10.1074/jbc.ra119.009251] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/12/2019] [Indexed: 01/13/2023] Open
Abstract
Human guanylate kinase (hGMPK) is the only known enzyme responsible for cellular GDP production, making it essential for cellular viability and proliferation. Moreover, hGMPK has been assigned a critical role in metabolic activation of antiviral and antineoplastic nucleoside-analog prodrugs. Given that hGMPK is indispensable for producing the nucleotide building blocks of DNA, RNA, and cGMP and that cancer cells possess elevated GTP levels, it is surprising that a detailed structural and functional characterization of hGMPK is lacking. Here, we present the first high-resolution structure of hGMPK in the apo form, determined with NMR spectroscopy. The structure revealed that hGMPK consists of three distinct regions designated as the LID, GMP-binding (GMP-BD), and CORE domains and is in an open configuration that is nucleotide binding-competent. We also demonstrate that nonsynonymous single-nucleotide variants (nsSNVs) of the hGMPK CORE domain distant from the nucleotide-binding site of this domain modulate enzymatic activity without significantly affecting hGMPK's structure. Finally, we show that knocking down the hGMPK gene in lung adenocarcinoma cell lines decreases cellular viability, proliferation, and clonogenic potential while not altering the proliferation of immortalized, noncancerous human peripheral airway cells. Taken together, our results provide an important step toward establishing hGMPK as a potential biomolecular target, from both an orthosteric (ligand-binding sites) and allosteric (location of CORE domain-located nsSNVs) standpoint.
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Affiliation(s)
- Nazimuddin Khan
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - Parag P Shah
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - David Ban
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - Pablo Trigo-Mouriño
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Marta G Carneiro
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Lynn DeLeeuw
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - William L Dean
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - John O Trent
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - Levi J Beverly
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - Manfred Konrad
- Enzyme Biochemistry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
| | - Donghan Lee
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
| | - T Michael Sabo
- Department of Medicine, James Graham Brown Cancer Center, University of Louisville, Louisville, Kentucky 40202
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3
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Alavi Z, Zocchi G. Dissipation at the angstrom scale: Probing the surface and interior of an enzyme. Phys Rev E 2018; 97:052402. [PMID: 29906977 DOI: 10.1103/physreve.97.052402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Indexed: 06/08/2023]
Abstract
Pursuing a materials science approach to understanding the deformability of enzymes, we introduce measurements of the phase of the mechanical response function within the nanorheology paradigm. Driven conformational motion of the enzyme is dissipative as characterized by the phase measurements. The dissipation originates both from the surface hydration layer and the interior of the molecule, probed by examining the effect of point mutations on the mechanics. We also document changes in the mechanics of the enzyme examined, guanylate kinase, upon binding its four substrates. GMP binding stiffens the molecule, ATP and ADP binding softens it, while there is no clear mechanical signature of GDP binding. A hyperactive two-Gly mutant is found to possibly trade specificity for speed. Global deformations of enzymes are shown to be dependent on both hydration layer and polypeptide chain dynamics.
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Affiliation(s)
- Zahra Alavi
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
- Department of Physics and Astronomy, Loyola Marymount University Los Angeles, Los Angeles, California 90095, USA
| | - Giovanni Zocchi
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
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4
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Khan N, Ban D, Trigo-Mourino P, Carneiro MG, Konrad M, Lee D, Sabo TM. 1H, 13C and 15N resonance assignment of human guanylate kinase. BIOMOLECULAR NMR ASSIGNMENTS 2018; 12:11-14. [PMID: 28861857 DOI: 10.1007/s12104-017-9771-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 08/28/2017] [Indexed: 06/07/2023]
Abstract
Human guanylate kinase (hGMPK) is a critical enzyme that, in addition to phosphorylating its physiological substrate (d)GMP, catalyzes the second phosphorylation step in the conversion of anti-viral and anti-cancer nucleoside analogs to their corresponding active nucleoside analog triphosphates. Until now, a high-resolution structure of hGMPK is unavailable and thus, we studied free hGMPK by NMR and assigned the chemical shift resonances of backbone and side chain 1H, 13C, and 15N nuclei as a first step towards the enzyme's structural and mechanistic analysis with atomic resolution.
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Affiliation(s)
- Nazimuddin Khan
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, 505 S. Hancock St., Louisville, KY, 40202, USA
- Enzyme Biochemistry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - David Ban
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, 505 S. Hancock St., Louisville, KY, 40202, USA
| | - Pablo Trigo-Mourino
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Marta G Carneiro
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
- ZoBio B.V., Biopartner building 2, J.H. Oortweg 19, 2333 CH, Leiden, The Netherlands
| | - Manfred Konrad
- Enzyme Biochemistry Group, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - Donghan Lee
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, 505 S. Hancock St., Louisville, KY, 40202, USA
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany
| | - T Michael Sabo
- James Graham Brown Cancer Center, Department of Medicine, University of Louisville, 505 S. Hancock St., Louisville, KY, 40202, USA.
- Department for NMR-Based Structural Biology, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077, Göttingen, Germany.
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5
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Eukaryotic-type serine/threonine kinase mediated phosphorylation at Thr 169 perturbs mycobacterial guanylate kinase activity. Biosci Rep 2017; 37:BSR20171048. [PMID: 28963370 PMCID: PMC5686395 DOI: 10.1042/bsr20171048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Revised: 09/23/2017] [Accepted: 09/25/2017] [Indexed: 01/22/2023] Open
Abstract
Guanylate kinase is an essential and conserved enzyme in nucleotide biosynthetic pathway that transfers phosphoryl group of ATP to GMP for yielding GDP. Here, we report the phosphorylation of guanylate kinase from Mycobacterium tuberculosis (mGmk) by eukaryotic-type Ser/Thr kinase, PknA. Mass spectrometric studies identified Thr101 and Thr169 as phosphorylatable residues in mGmk. To evaluate the significance of phosphorylation in these threonines, two point (T101A and T169A) and one double (T101A-T169A) mutants were generated. The kinase assay with these mutant proteins revealed the major contribution of Thr169 compared with Thr101 in the phosphorylation of mGmk. Kinetic analysis indicated that p-mGmk was deficient in its enzymatic activity compared with that of its un-phosphorylated counterpart. Surprisingly, its phosphoablated (T169A) as well as phosphomimic (T169E) variants exhibited decreased activity as was observed with p-mGmk. Structural analysis suggested that phosphorylation of Thr169 might affect its interaction with Arg166, which is crucial for the functioning of mGmk. In fact, the R166A and R166K mutant proteins displayed a drastic decrease in enzymatic activity compared with that of the wild-type mGmk. Molecular dynamics (MD) studies of mGmk revealed that upon phosphorylation of Thr169, the interactions of Arg165/Arg166 with Glu158, Asp121 and residues of the loop in GMP-binding domain are perturbed. Taken together, our results illuminate the mechanistic insights into phosphorylation-mediated modulation of the catalytic activity of mGmk.
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6
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Biswas A, Shukla A, Chaudhary SK, Santhosh R, Jeyakanthan J, Sekar K. Structural studies of a hyperthermophilic thymidylate kinase enzyme reveal conformational substates along the reaction coordinate. FEBS J 2017. [PMID: 28627020 DOI: 10.1111/febs.14140] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Thymidylate kinase (TMK) is a key enzyme which plays an important role in DNA synthesis. It belongs to the family of nucleoside monophosphate kinases, several of which undergo structure-encoded conformational changes to perform their function. However, the absence of three-dimensional structures for all the different reaction intermediates of a single TMK homolog hinders a clear understanding of its functional mechanism. We herein report the different conformational states along the reaction coordinate of a hyperthermophilic TMK from Aquifex aeolicus, determined via X-ray diffraction and further validated through normal-mode studies. The analyses implicate an arginine residue in the Lid region in catalysis, which was confirmed through site-directed mutagenesis and subsequent enzyme assays on the wild-type protein and mutants. Furthermore, the enzyme was found to exhibit broad specificity toward phosphate group acceptor nucleotides. Our comprehensive analyses of the conformational landscape of TMK, together with associated biochemical experiments, provide insights into the mechanistic details of TMK-driven catalysis, for example, the order of substrate binding and the reaction mechanism for phosphate transfer. Such a study has utility in the design of potent inhibitors for these enzymes. DATABASE Structural data are available in the PDB under the accession numbers 2PBR, 4S2E, 5H5B, 5XAI, 4S35, 5XB2, 5H56, 5XB3, 5H5K, 5XB5, and 5XBH.
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Affiliation(s)
- Ansuman Biswas
- Department of Physics, Indian Institute of Science, Bangalore, India
| | - Arpit Shukla
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
| | | | | | | | - Kanagaraj Sekar
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore, India
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7
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Strain analysis of protein structures and low dimensionality of mechanical allosteric couplings. Proc Natl Acad Sci U S A 2016; 113:E5847-E5855. [PMID: 27655887 DOI: 10.1073/pnas.1609462113] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In many proteins, especially allosteric proteins that communicate regulatory states from allosteric to active sites, structural deformations are functionally important. To understand these deformations, dynamical experiments are ideal but challenging. Using static structural information, although more limited than dynamical analysis, is much more accessible. Underused for protein analysis, strain is the natural quantity for studying local deformations. We calculate strain tensor fields for proteins deformed by ligands or thermal fluctuations using crystal and NMR structure ensembles. Strains-primarily shears-show deformations around binding sites. These deformations can be induced solely by ligand binding at distant allosteric sites. Shears reveal quasi-2D paths of mechanical coupling between allosteric and active sites that may constitute a widespread mechanism of allostery. We argue that strain-particularly shear-is the most appropriate quantity for analysis of local protein deformations. This analysis can reveal mechanical and biological properties of many proteins.
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8
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Abstract
The development and application of a highly versatile suite of tools for mycobacterial genetics, coupled with widespread use of "omics" approaches to elucidate the structure, function, and regulation of mycobacterial proteins, has led to spectacular advances in our understanding of the metabolism and physiology of mycobacteria. In this article, we provide an update on nucleotide metabolism and DNA replication in mycobacteria, highlighting key findings from the past 10 to 15 years. In the first section, we focus on nucleotide metabolism, ranging from the biosynthesis, salvage, and interconversion of purine and pyrimidine ribonucleotides to the formation of deoxyribonucleotides. The second part of the article is devoted to DNA replication, with a focus on replication initiation and elongation, as well as DNA unwinding. We provide an overview of replication fidelity and mutation rates in mycobacteria and summarize evidence suggesting that DNA replication occurs during states of low metabolic activity, and conclude by suggesting directions for future research to address key outstanding questions. Although this article focuses primarily on observations from Mycobacterium tuberculosis, it is interspersed, where appropriate, with insights from, and comparisons with, other mycobacterial species as well as better characterized bacterial models such as Escherichia coli. Finally, a common theme underlying almost all studies of mycobacterial metabolism is the potential to identify and validate functions or pathways that can be exploited for tuberculosis drug discovery. In this context, we have specifically highlighted those processes in mycobacterial DNA replication that might satisfy this critical requirement.
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9
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Purification and characterization of guanylate kinase, a nucleoside monophosphate kinase of Brugia malayi. Parasitology 2014; 141:1341-52. [DOI: 10.1017/s0031182014000675] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYGuanylate kinase, a nucleoside monophosphate kinase of Brugia malayi which is involved in reversible transfer of phosphate groups from ATP to GMP, was cloned, expressed and characterized. The native molecular mass of BmGK was found to be 45 kDa as determined by size exclusion chromatography and glutaraldehyde cross-linking which revealed that the protein is homodimer in nature. This is a unique characteristic among known eukaryotic GKs. GMP and ATP served as the most effective phosphate acceptor and donor, respectively. Recombinant BmGK utilized both GMP and dGMP, as substrates showing Km values of 30 and 38 μm, respectively. Free Mg+2 (un-complexed to ATP) and GTP play a regulatory role in catalysis of BmGK. The enzyme showed higher catalytic efficiency as compared with human GK and showed ternary complex (BmGK-GMP-ATP) formation with sequential substrate binding. The secondary structure of BmGK consisted of 45% α-helices, 18% β-sheets as revealed by CD analysis. Homology modelling and docking with GMP revealed conserved substrate binding residues with slight differences. Differences in kinetic properties and oligomerization of BmGK compared with human GK can provide the way for design of parasite-specific inhibitors.
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10
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Delalande O, Sacquin-Mora S, Baaden M. Enzyme closure and nucleotide binding structurally lock guanylate kinase. Biophys J 2011; 101:1440-9. [PMID: 21943425 DOI: 10.1016/j.bpj.2011.07.048] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2011] [Revised: 07/15/2011] [Accepted: 07/28/2011] [Indexed: 02/02/2023] Open
Abstract
We investigate the conformational dynamics and mechanical properties of guanylate kinase (GK) using a multiscale approach combining high-resolution atomistic molecular dynamics and low-resolution Brownian dynamics simulations. The GK enzyme is subject to large conformational changes, leading from an open to a closed form, which are further influenced by the presence of nucleotides. As suggested by recent work on simple coarse-grained models of apo-GK, we primarily focus on GK's closure mechanism with the aim to establish a detailed picture of the hierarchy and chronology of structural events essential for the enzymatic reaction. We have investigated open-versus-closed, apo-versus-holo, and substrate-versus-product-loaded forms of the GK enzyme. Bound ligands significantly modulate the mechanical and dynamical properties of GK and rigidity profiles of open and closed states hint at functionally important differences. Our data emphasizes the role of magnesium, highlights a water channel permitting active site hydration, and reveals a structural lock that stabilizes the closed form of the enzyme.
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Affiliation(s)
- Olivier Delalande
- Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, Centre National de la Recherche Scientifique, UPR9080, Université Paris Diderot, Sorbonne Paris Cité, Paris, France
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11
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Sacquin-Mora S, Delalande O, Baaden M. Functional modes and residue flexibility control the anisotropic response of guanylate kinase to mechanical stress. Biophys J 2011; 99:3412-9. [PMID: 21081090 DOI: 10.1016/j.bpj.2010.09.026] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 09/11/2010] [Accepted: 09/15/2010] [Indexed: 01/27/2023] Open
Abstract
The coupling between the mechanical properties of enzymes and their biological activity is a well-established feature that has been the object of numerous experimental and theoretical works. In particular, recent experiments show that enzymatic function can be modulated anisotropically by mechanical stress. We study such phenomena using a method for investigating local flexibility on the residue scale that combines a reduced protein representation with Brownian dynamics simulations. We performed calculations on the enzyme guanylate kinase to study its mechanical response when submitted to anisotropic deformations. The resulting modifications of the protein's rigidity profile can be related to the changes in substrate binding affinity observed experimentally. Further analysis of the principal components of motion of the trajectories shows how the application of a mechanical constraint on the protein can disrupt its dynamics, thus leading to a decrease of the enzyme's catalytic rate. Eventually, a systematic probe of the protein surface led to the prediction of potential hotspots where the application of an external constraint would produce a large functional response both from the mechanical and dynamical points of view. Such enzyme-engineering approaches open the possibility to tune catalytic function by varying selected external forces.
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Affiliation(s)
- Sophie Sacquin-Mora
- Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR9080, Paris, France.
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12
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Labesse G, Benkali K, Salard-Arnaud I, Gilles AM, Munier-Lehmann H. Structural and functional characterization of the Mycobacterium tuberculosis uridine monophosphate kinase: insights into the allosteric regulation. Nucleic Acids Res 2010; 39:3458-72. [PMID: 21149268 PMCID: PMC3082897 DOI: 10.1093/nar/gkq1250] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Nucleoside Monophosphate Kinases (NMPKs) family are key enzymes in nucleotide metabolism. Bacterial UMPKs depart from the main superfamily of NMPKs. Having no eukaryotic counterparts they represent attractive therapeutic targets. They are regulated by GTP and UTP, while showing different mechanisms in Gram(+), Gram(–) and archaeal bacteria. In this work, we have characterized the mycobacterial UMPK (UMPKmt) combining enzymatic and structural investigations with site-directed mutagenesis. UMPKmt exhibits cooperativity toward ATP and an allosteric regulation by GTP and UTP. The crystal structure of the complex of UMPKmt with GTP solved at 2.5 Å, was merely identical to the modelled apo-form, in agreement with SAXS experiments. Only a small stretch of residues was affected upon nucleotide binding, pointing out the role of macromolecular dynamics rather than major structural changes in the allosteric regulation of bacterial UMPKs. We further probe allosteric regulation by site-directed mutagenesis. In particular, a key residue involved in the allosteric regulation of this enzyme was identified.
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Affiliation(s)
- Gilles Labesse
- Atelier de Bio- et Chimie Informatique Structurale, CNRS, UMR5048, Centre de Biochimie Structurale, 29 rue de Navacelles, F-34090 Montpellier, France
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13
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Kandeel M, Kitade Y. Binding dynamics and energetic insight into the molecular forces driving nucleotide binding by guanylate kinase. J Mol Recognit 2010; 24:322-32. [PMID: 21360614 DOI: 10.1002/jmr.1074] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 07/16/2010] [Accepted: 07/16/2010] [Indexed: 11/11/2022]
Abstract
Plasmodium deoxyguanylate pathways are an attractive area of investigation for future metabolic and drug discovery studies due to their unique substrate specificities. We investigated the energetic contribution to guanylate kinase substrate binding and the forces underlying ligand recognition. In the range from 20 to 35°C, the thermodynamic profiles displayed marked decrease in binding enthalpy, while the free energy of binding showed little changes. GMP produced a large binding heat capacity change of -356 cal mol(-1) K(-1), indicating considerable conformational changes upon ligand binding. Interestingly, the calculated ΔCp was -32 cal mol(-1) K(-1), indicating that the accessible surface area is not the central change in substrate binding, and that other entropic forces, including conformational changes, are more predominant. The thermodynamic signature for GMP is inconsistent with rigid-body association, while dGMP showed more or less rigid-body association. These binding profiles explain the poor catalytic efficiency and low affinity for dGMP compared with GMP. At low temperature, the ligands bind to the receptor site under the effect of hydrophobic forces. Interestingly, by increasing the temperature, the entropic forces gradually vanish and proceed to a nonfavorable contribution, and the interaction occurs mainly through bonding, electrostatic forces, and van der Waals interactions.
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Affiliation(s)
- Mahmoud Kandeel
- Department of Pharmacology, Faculty of Veterinary Medicine, Kafr El-Shikh University, Kafr El-Shikh 33516, Egypt.
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14
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Delalande O, Férey N, Grasseau G, Baaden M. Complex molecular assemblies at hand via interactive simulations. J Comput Chem 2009; 30:2375-87. [PMID: 19353597 DOI: 10.1002/jcc.21235] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Studying complex molecular assemblies interactively is becoming an increasingly appealing approach to molecular modeling. Here we focus on interactive molecular dynamics (IMD) as a textbook example for interactive simulation methods. Such simulations can be useful in exploring and generating hypotheses about the structural and mechanical aspects of biomolecular interactions. For the first time, we carry out low-resolution coarse-grain IMD simulations. Such simplified modeling methods currently appear to be more suitable for interactive experiments and represent a well-balanced compromise between an important gain in computational speed versus a moderate loss in modeling accuracy compared to higher resolution all-atom simulations. This is particularly useful for initial exploration and hypothesis development for rare molecular interaction events. We evaluate which applications are currently feasible using molecular assemblies from 1900 to over 300,000 particles. Three biochemical systems are discussed: the guanylate kinase (GK) enzyme, the outer membrane protease T and the soluble N-ethylmaleimide-sensitive factor attachment protein receptors complex involved in membrane fusion. We induce large conformational changes, carry out interactive docking experiments, probe lipid-protein interactions and are able to sense the mechanical properties of a molecular model. Furthermore, such interactive simulations facilitate exploration of modeling parameters for method improvement. For the purpose of these simulations, we have developed a freely available software library called MDDriver. It uses the IMD protocol from NAMD and facilitates the implementation and application of interactive simulations. With MDDriver it becomes very easy to render any particle-based molecular simulation engine interactive. Here we use its implementation in the Gromacs software as an example.
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Affiliation(s)
- Olivier Delalande
- Institut de Biologie Physico-Chimique, Laboratoire de Biochimie Théorique, CNRS UPR 9080, 13, rue Pierre et Marie Curie, Paris F-75005, France
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15
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Kandeel M, Nakanishi M, Ando T, El-Shazly K, Yosef T, Ueno Y, Kitade Y. Molecular cloning, expression, characterization and mutation of Plasmodium falciparum guanylate kinase. Mol Biochem Parasitol 2008; 159:130-3. [PMID: 18374996 DOI: 10.1016/j.molbiopara.2008.02.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2007] [Revised: 01/31/2008] [Accepted: 02/11/2008] [Indexed: 11/19/2022]
Abstract
The present work describes cloning, expression, purification, characterization, and mutation of Plasmodium falciparum guanylate kinase (PlasmoDB ID PFI1420w). Amino-acid sequence alignment revealed important differences especially in K42-V51, Y73-A77, and F100-L110, which include residues important for kinase activity, and at helix 3, which is important for domain movements. The catalytic efficiency for dGMP was 22-fold lower than that for GMP, whose value is the lowest among known guanylate kinases. dGMP was found to a competitive inhibitor for GMP with K(i)=0.148 mM and a mixed-type inhibitor with regard to ATP with measured K(i)=0.4 mM. The specificity constant (K(cat)/K(m)) of the four examined mutants varied for natural substrate GMP/dGMP, indicating the involvement of different mechanisms in substrate recognition and subsequent loop-domain movement. These results show that P. falciparum guanylate kinase is structurally and biochemically distinct from other guanylate kinases and could be a possible target in drug development.
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Affiliation(s)
- Mahmoud Kandeel
- Department of Biomolecular Science, Faculty of Engineering, Gifu University, Gifu, Japan
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16
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Ofiteru A, Bucurenci N, Alexov E, Bertrand T, Briozzo P, Munier-Lehmann H, Gilles AM. Structural and functional consequences of single amino acid substitutions in the pyrimidine base binding pocket of Escherichia coli CMP kinase. FEBS J 2007; 274:3363-73. [PMID: 17542990 DOI: 10.1111/j.1742-4658.2007.05870.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bacterial CMP kinases are specific for CMP and dCMP, whereas the related eukaryotic NMP kinase phosphorylates CMP and UMP with similar efficiency. To explain these differences in structural terms, we investigated the contribution of four key amino acids interacting with the pyrimidine ring of CMP (Ser36, Asp132, Arg110 and Arg188) to the stability, catalysis and substrate specificity of Escherichia coli CMP kinase. In contrast to eukaryotic UMP/CMP kinases, which interact with the nucleobase via one or two water molecules, bacterial CMP kinase has a narrower NMP-binding pocket and a hydrogen-bonding network involving the pyrimidine moiety specific for the cytosine nucleobase. The side chains of Arg110 and Ser36 cannot establish hydrogen bonds with UMP, and their substitution by hydrophobic amino acids simultaneously affects the K(m) of CMP/dCMP and the k(cat) value. Substitution of Ser for Asp132 results in a moderate decrease in stability without significant changes in K(m) value for CMP and dCMP. Replacement of Arg188 with Met does not affect enzyme stability but dramatically decreases the k(cat)/K(m) ratio compared with wild-type enzyme. This effect might be explained by opening of the enzyme/nucleotide complex, so that the sugar no longer interacts with Asp185. The reaction rate for different modified CMP kinases with ATP as a variable substrate indicated that none of changes induced by these amino acid substitutions was 'propagated' to the ATP subsite. This 'modular' behavior of E. coli CMP kinase is unique in comparison with other NMP kinases.
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Affiliation(s)
- Augustin Ofiteru
- Laboratory of Enzymology and Applied Microbiology, Cantacuzino Institute, Bucharest, Romania
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Rudolph MG, Heissmann R, Wittmann JG, Klostermeier D. Crystal structure and nucleotide binding of the Thermus thermophilus RNA helicase Hera N-terminal domain. J Mol Biol 2006; 361:731-43. [PMID: 16890241 DOI: 10.1016/j.jmb.2006.06.065] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 06/20/2006] [Accepted: 06/26/2006] [Indexed: 02/06/2023]
Abstract
DEAD box RNA helicases use the energy of ATP hydrolysis to unwind double-stranded RNA regions or to disrupt RNA/protein complexes. A minimal RNA helicase comprises nine conserved motifs distributed over two RecA-like domains. The N-terminal domain contains all motifs involved in nucleotide binding, namely the Q-motif, the DEAD box, and the P-loop, as well as the SAT motif, which has been implicated in the coordination of ATP hydrolysis and RNA unwinding. We present here the crystal structure of the N-terminal domain of the Thermus thermophilus RNA helicase Hera in complex with adenosine monophosphate (AMP). Upon binding of AMP the P-loop adopts a partially collapsed or half-open conformation that is still connected to the DEAD box motif, and the DEAD box in turn is linked to the SAT motif via hydrogen bonds. This network of interactions communicates changes in the P-loop conformation to distant parts of the helicase. The affinity of AMP is comparable to that of ADP and ATP, substantiating that the binding energy from additional phosphate moieties is directly converted into conformational changes of the entire helicase. Importantly, the N-terminal Hera domain forms a dimer in the crystal similar to that seen in another thermophilic prokaryote. It is possible that this mode of dimerization represents the prototypic architecture in RNA helicases of thermophilic origin.
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Affiliation(s)
- Markus G Rudolph
- Department of Molecular Structural Biology, University of Göttingen, D-37077 Göttingen, Germany
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Hible G, Daalova P, Gilles AM, Cherfils J. Crystal structures of GMP kinase in complex with ganciclovir monophosphate and Ap5G. Biochimie 2006; 88:1157-64. [PMID: 16690197 DOI: 10.1016/j.biochi.2006.04.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Accepted: 04/04/2006] [Indexed: 11/24/2022]
Abstract
Guanosine monophosphate kinases (GMPK), by catalyzing the phosphorylation of GMP or dGMP, are of dual potential in assisting the activation of anti-viral prodrugs or as candidates for antibiotic strategies. Human GMPK is an obligate step for the activation of acyclic guanosine analogs, such as ganciclovir, which necessitate efficient phosphorylation, while GMPK from bacterial pathogens, in which this enzyme is essential, are potential targets for therapeutic inhibition. Here we analyze these two aspects of GMPK activity with the crystal structures of Escherichia coli GMPK in complex with ganciclovir-monophosphate (GCV-MP) and with a bi-substrate inhibitor, Ap5G. GCV-MP binds as GMP to the GMP-binding domain, which is identical in E. coli and human GMPKs, but unlike the natural substrate fails to stabilize the closed, catalytically-competent conformation of this domain. Comparison with GMP- and GDP-bound GMPK structures identifies the 2'hydroxyl of the ribose moiety as responsible for hooking the GMP-binding domain onto the CORE domain. Absence of this hydroxyl in GCV-MP impairs the stabilization of the active conformation, and explains why GCV-MP is phosphorylated less efficiently than GMP, but as efficiently as dGMP. In contrast, Ap5G is an efficient inhibitor of GMPK. The crystal structure shows that Ap5G locks an incompletely closed conformation of the enzyme, in which the adenine moiety is located outside its expected binding site. Instead, it binds at a subunit interface that is unique to the bacterial enzyme, which is in equilibrium between a dimeric and an hexameric form in solution. This suggests that inhibitors could be designed to bind at this interface such as to prevent nucleotide-induced domain closure. Altogether, these complexes point to domain motions as critical components to be evaluated in therapeutic strategies targeting NMP kinases, with opposite effects depending on whether efficient phosphorylation or inhibition is being sought after.
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Affiliation(s)
- G Hible
- Laboratoire d'Enzymologie et Biochimie Structurales, bâtiment 34, CNRS, avenue de la Terrasse, 91198 Gif sur Yvette cedex, France
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Hible G, Renault L, Schaeffer F, Christova P, Zoe Radulescu A, Evrin C, Gilles AM, Cherfils J. Calorimetric and crystallographic analysis of the oligomeric structure of Escherichia coli GMP kinase. J Mol Biol 2005; 352:1044-59. [PMID: 16140325 DOI: 10.1016/j.jmb.2005.07.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 07/11/2005] [Accepted: 07/14/2005] [Indexed: 10/25/2022]
Abstract
Guanosine monophosphate kinases (GMPKs), which catalyze the phosphorylation of GMP and dGMP to their diphosphate form, have been characterized as monomeric enzymes in eukaryotes and prokaryotes. Here, we report that GMPK from Escherichia coli (ecGMPK) assembles in solution and in the crystal as several different oligomers. Thermodynamic analysis of ecGMPK using differential scanning calorimetry shows that the enzyme is in equilibrium between a dimer and higher order oligomers, whose relative amounts depend on protein concentration, ionic strength, and the presence of ATP. Crystallographic structures of ecGMPK in the apo, GMP and GDP-bound forms were solved at 3.2A, 2.9A and 2.4A resolution, respectively. ecGMPK forms a hexamer with D3 symmetry in all crystal forms, in which the two nucleotide-binding domains are able to undergo closure comparable to that of monomeric GMPKs. The 2-fold and 3-fold interfaces involve a 20-residue C-terminal extension and a sequence signature, respectively, that are missing from monomeric eukaryotic GMPKs, explaining why ecGMPK forms oligomers. These signatures are found in GMPKs from proteobacteria, some of which are human pathogens. GMPKs from these bacteria are thus likely to form the same quaternary structures. The shift of the thermodynamic equilibrium towards the dimer at low ecGMPK concentration together with the observation that inter-subunit interactions partially occlude the ATP-binding site in the hexameric structure suggest that the dimer may be the active species at physiological enzyme concentration.
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Affiliation(s)
- Guillaume Hible
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Gif sur Yvette 91198, France
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