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Bonfrate S, Ferré N, Huix-Rotllant M. Analytic Gradients for the Electrostatic Embedding QM/MM Model in Periodic Boundary Conditions Using Particle-Mesh Ewald Sums and Electrostatic Potential Fitted Charge Operators. J Chem Theory Comput 2024; 20:4338-4349. [PMID: 38712506 DOI: 10.1021/acs.jctc.4c00201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Long-range electrostatic effects are fundamental for describing chemical reactivity in the condensed phase. Here, we present the methodology of an efficient quantum mechanical/molecular mechanical (QM/MM) model in periodic boundary conditions (PBC) compatible with QM/MM boundaries at chemical bonds. The method combines electrostatic potential fitted charge operators and electrostatic potentials derived from the smooth particle-mesh Ewald (PME) sum approach. The total energy and its analytic first derivatives with respect to QM, MM, and lattice vectors allow QM/MM molecular dynamics (MD) in the most common thermodynamic ensembles. We demonstrate the robustness of the method by performing a QM/MM MD equilibration of methanol in water. We simulate the cis/trans isomerization free-energy profiles in water of proline amino acid and a proline-containing oligopeptide, showing a correct description of the reaction barrier. Our PBC-compatible QM/MM model can efficiently be used to study the chemical reactivity in the condensed phase and enzymatic catalysis.
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Affiliation(s)
| | - Nicolas Ferré
- Aix-Marseille Univ, CNRS, ICR, Marseille 13013, France
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2
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Palaniappan C, Rajendran S, Sekar K. Alternate conformations found in protein structures implies biological functions: A case study using cyclophilin A. Curr Res Struct Biol 2024; 7:100145. [PMID: 38690327 PMCID: PMC11059445 DOI: 10.1016/j.crstbi.2024.100145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 03/16/2024] [Accepted: 04/15/2024] [Indexed: 05/02/2024] Open
Abstract
Protein dynamics linked to numerous biomolecular functions, such as ligand binding, allosteric regulation, and catalysis, must be better understood at the atomic level. Reactive atoms of key residues drive a repertoire of biomolecular functions by flipping between alternate conformations or conformational substates, seldom found in protein structures. Probing such sparsely sampled alternate conformations would provide mechanistic insight into many biological functions. We are therefore interested in evaluating the instance of amino acids adopted alternate conformations, either in backbone or side-chain atoms or in both. Accordingly, over 70000 protein structures appear to contain alternate conformations only 'A' and 'B' for any atom, particularly the instance of amino acids that adopted alternate conformations are more for Arg, Cys, Met, and Ser than others. The resulting protein structure analysis depicts that amino acids with alternate conformations are mainly found in the helical and β-regions and are often seen in high-resolution X-ray crystal structures. Furthermore, a case study on human cyclophilin A (CypA) was performed to explain the pre-existing intrinsic dynamics of catalytically critical residues from the CypA and how such intrinsic dynamics perturbed upon Ser99Thr mutation using molecular dynamics simulations on the ns-μs timescale. Simulation results demonstrated that the Ser99Thr mutation had impaired the alternate conformations or the catalytically productive micro-environment of Phe113, mimicking the experimentally observed perturbation captured by X-ray crystallography. In brief, a deeper comprehension of alternate conformations adopted by the amino acids may shed light on the interplay between protein structure, dynamics, and function.
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Affiliation(s)
- Chandrasekaran Palaniappan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Santhosh Rajendran
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
- Department of Computational and Data Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Kanagaraj Sekar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
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3
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Löffler JG, Deniz E, Feid C, Franz VG, Bredenbeck J. Versatile Vibrational Energy Sensors for Proteins. Angew Chem Int Ed Engl 2022; 61:e202200648. [PMID: 35226765 PMCID: PMC9401566 DOI: 10.1002/anie.202200648] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Indexed: 11/10/2022]
Abstract
Vibrational energy transfer (VET) is emerging as key mechanism for protein functions, possibly playing an important role for energy dissipation, allosteric regulation, and enzyme catalysis. A deep understanding of VET is required to elucidate its role in such processes. Ultrafast VIS-pump/IR-probe spectroscopy can detect pathways of VET in proteins. However, the requirement of having a VET donor and a VET sensor installed simultaneously limits the possible target proteins and sites; to increase their number we compare six IR labels regarding their utility as VET sensors. We compare these labels in terms of their FTIR, and VET signature in VET donor-sensor dipeptides in different solvents. Furthermore, we incorporated four of these labels in PDZ3 to assess their capabilities in more complex systems. Our results show that different IR labels can be used interchangeably, allowing for free choice of the right label depending on the system under investigation and the methods available.
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Affiliation(s)
- Jan G. Löffler
- Institute of BiophysicsGoethe University FrankfurtMax-von-Laue-Straße 160438Frankfurt (Main)Germany
| | - Erhan Deniz
- Institute of BiophysicsGoethe University FrankfurtMax-von-Laue-Straße 160438Frankfurt (Main)Germany
| | - Carolin Feid
- Institute of BiophysicsGoethe University FrankfurtMax-von-Laue-Straße 160438Frankfurt (Main)Germany
| | - Valentin G. Franz
- Institute of BiophysicsGoethe University FrankfurtMax-von-Laue-Straße 160438Frankfurt (Main)Germany
| | - Jens Bredenbeck
- Institute of BiophysicsGoethe University FrankfurtMax-von-Laue-Straße 160438Frankfurt (Main)Germany
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4
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Löffler JG, Deniz E, Feid C, Franz VG, Bredenbeck J. Versatile Vibrational Energy Sensors for Proteins. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202200648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Jan G. Löffler
- Institute of Biophysics Goethe University Frankfurt Max-von-Laue-Straße 1 60438 Frankfurt (Main) Germany
| | - Erhan Deniz
- Institute of Biophysics Goethe University Frankfurt Max-von-Laue-Straße 1 60438 Frankfurt (Main) Germany
| | - Carolin Feid
- Institute of Biophysics Goethe University Frankfurt Max-von-Laue-Straße 1 60438 Frankfurt (Main) Germany
| | - Valentin G. Franz
- Institute of Biophysics Goethe University Frankfurt Max-von-Laue-Straße 1 60438 Frankfurt (Main) Germany
| | - Jens Bredenbeck
- Institute of Biophysics Goethe University Frankfurt Max-von-Laue-Straße 1 60438 Frankfurt (Main) Germany
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5
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Uversky VN, Giuliani A. Networks of Networks: An Essay on Multi-Level Biological Organization. Front Genet 2021; 12:706260. [PMID: 34234818 PMCID: PMC8255927 DOI: 10.3389/fgene.2021.706260] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 05/31/2021] [Indexed: 01/01/2023] Open
Abstract
The multi-level organization of nature is self-evident: proteins do interact among them to give rise to an organized metabolism, while in the same time each protein (a single node of such interaction network) is itself a network of interacting amino-acid residues allowing coordinated motion of the macromolecule and systemic effect as allosteric behavior. Similar pictures can be drawn for structure and function of cells, organs, tissues, and ecological systems. The majority of biologists are used to think that causally relevant events originate from the lower level (the molecular one) in the form of perturbations, that “climb up” the hierarchy reaching the ultimate layer of macroscopic behavior (e.g., causing a specific disease). Such causative model, stemming from the usual genotype-phenotype distinction, is not the only one. As a matter of fact, one can observe top-down, bottom-up, as well as middle-out perturbation/control trajectories. The recent complex network studies allow to go further the pure qualitative observation of the existence of both non-linear and non-bottom-up processes and to uncover the deep nature of multi-level organization. Here, taking as paradigm protein structural and interaction networks, we review some of the most relevant results dealing with between networks communication shedding light on the basic principles of complex system control and dynamics and offering a more realistic frame of causation in biology.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, United States
| | - Alessandro Giuliani
- Department of Environment and Health, Istituto Superiore di Sanità, Rome, Italy
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6
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Galdadas I, Qu S, Oliveira ASF, Olehnovics E, Mack AR, Mojica MF, Agarwal PK, Tooke CL, Gervasio FL, Spencer J, Bonomo RA, Mulholland AJ, Haider S. Allosteric communication in class A β-lactamases occurs via cooperative coupling of loop dynamics. eLife 2021; 10:e66567. [PMID: 33755013 PMCID: PMC8060031 DOI: 10.7554/elife.66567] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/19/2021] [Indexed: 12/16/2022] Open
Abstract
Understanding allostery in enzymes and tools to identify it offer promising alternative strategies to inhibitor development. Through a combination of equilibrium and nonequilibrium molecular dynamics simulations, we identify allosteric effects and communication pathways in two prototypical class A β-lactamases, TEM-1 and KPC-2, which are important determinants of antibiotic resistance. The nonequilibrium simulations reveal pathways of communication operating over distances of 30 Å or more. Propagation of the signal occurs through cooperative coupling of loop dynamics. Notably, 50% or more of clinically relevant amino acid substitutions map onto the identified signal transduction pathways. This suggests that clinically important variation may affect, or be driven by, differences in allosteric behavior, providing a mechanism by which amino acid substitutions may affect the relationship between spectrum of activity, catalytic turnover, and potential allosteric behavior in this clinically important enzyme family. Simulations of the type presented here will help in identifying and analyzing such differences.
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Affiliation(s)
- Ioannis Galdadas
- University College London, Department of ChemistryLondonUnited Kingdom
| | - Shen Qu
- University College London School of Pharmacy, Pharmaceutical and Biological ChemistryLondonUnited Kingdom
| | - Ana Sofia F Oliveira
- University of Bristol, Centre for Computational Chemistry, School of ChemistryBristolUnited Kingdom
| | - Edgar Olehnovics
- University College London School of Pharmacy, Pharmaceutical and Biological ChemistryLondonUnited Kingdom
| | - Andrew R Mack
- Veterans Affairs Northeast Ohio Healthcare System, Research ServiceClevelandUnited States
- Case Western Reserve University, Department of Molecular Biology and MicrobiologyClevelandUnited States
| | - Maria F Mojica
- Veterans Affairs Northeast Ohio Healthcare System, Research ServiceClevelandUnited States
- Case Western Reserve University, Department of Infectious Diseases, School of MedicineClevelandUnited States
| | - Pratul K Agarwal
- Department of Physiological Sciences and High-Performance Computing Center, Oklahoma State UniversityStillwaterUnited States
| | - Catherine L Tooke
- University of Bristol, School of Cellular and Molecular MedicineBristolUnited Kingdom
| | - Francesco Luigi Gervasio
- University College London, Department of ChemistryLondonUnited Kingdom
- University College London, Institute of Structural and Molecular BiologyLondonUnited Kingdom
- University of Geneva, Pharmaceutical SciencesGenevaSwitzerland
| | - James Spencer
- University of Bristol, School of Cellular and Molecular MedicineBristolUnited Kingdom
| | - Robert A Bonomo
- Veterans Affairs Northeast Ohio Healthcare System, Research ServiceClevelandUnited States
- Case Western Reserve University, Department of Molecular Biology and MicrobiologyClevelandUnited States
- Case Western Reserve University, Department of Infectious Diseases, School of MedicineClevelandUnited States
- Case Western Reserve University, Department of BiochemistryClevelandUnited States
- Case Western Reserve University, Department of PharmacologyClevelandUnited States
- Case Western Reserve University, Department of Proteomics and BioinformaticsClevelandUnited States
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES)ClevelandUnited States
| | - Adrian J Mulholland
- University of Bristol, Centre for Computational Chemistry, School of ChemistryBristolUnited Kingdom
| | - Shozeb Haider
- University College London School of Pharmacy, Pharmaceutical and Biological ChemistryLondonUnited Kingdom
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Abstract
The disaccharide trehalose is accumulated in the cytoplasm of some organisms in response to harsh environmental conditions. Trehalose biosynthesis and accumulation are important for the survival of such organisms by protecting the structure and function of proteins and membranes. Trehalose affects the dynamics of proteins and water molecules in the bulk and the protein hydration shell. Enzyme catalysis and other processes dependent on protein dynamics are affected by the viscosity generated by trehalose, as described by the Kramers’ theory of rate reactions. Enzyme/protein stabilization by trehalose against thermal inactivation/unfolding is also explained by the viscosity mediated hindering of the thermally generated structural dynamics, as described by Kramers’ theory. The analysis of the relationship of viscosity–protein dynamics, and its effects on enzyme/protein function and other processes (thermal inactivation and unfolding/folding), is the focus of the present work regarding the disaccharide trehalose as the viscosity generating solute. Finally, trehalose is widely used (alone or in combination with other compounds) in the stabilization of enzymes in the laboratory and in biotechnological applications; hence, considering the effect of viscosity on catalysis and stability of enzymes may help to improve the results of trehalose in its diverse uses/applications.
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8
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Juárez-Jiménez J, Gupta AA, Karunanithy G, Mey ASJS, Georgiou C, Ioannidis H, De Simone A, Barlow PN, Hulme AN, Walkinshaw MD, Baldwin AJ, Michel J. Dynamic design: manipulation of millisecond timescale motions on the energy landscape of cyclophilin A. Chem Sci 2020; 11:2670-2680. [PMID: 34084326 PMCID: PMC8157532 DOI: 10.1039/c9sc04696h] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/14/2020] [Indexed: 12/21/2022] Open
Abstract
Proteins need to interconvert between many conformations in order to function, many of which are formed transiently, and sparsely populated. Particularly when the lifetimes of these states approach the millisecond timescale, identifying the relevant structures and the mechanism by which they interconvert remains a tremendous challenge. Here we introduce a novel combination of accelerated MD (aMD) simulations and Markov state modelling (MSM) to explore these 'excited' conformational states. Applying this to the highly dynamic protein CypA, a protein involved in immune response and associated with HIV infection, we identify five principally populated conformational states and the atomistic mechanism by which they interconvert. A rational design strategy predicted that the mutant D66A should stabilise the minor conformations and substantially alter the dynamics, whereas the similar mutant H70A should leave the landscape broadly unchanged. These predictions are confirmed using CPMG and R1ρ solution state NMR measurements. By efficiently exploring functionally relevant, but sparsely populated conformations with millisecond lifetimes in silico, our aMD/MSM method has tremendous promise for the design of dynamic protein free energy landscapes for both protein engineering and drug discovery.
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Affiliation(s)
- Jordi Juárez-Jiménez
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Arun A Gupta
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Gogulan Karunanithy
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Antonia S J S Mey
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Charis Georgiou
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Harris Ioannidis
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Alessio De Simone
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Paul N Barlow
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Alison N Hulme
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
| | - Malcolm D Walkinshaw
- School of Biological Sciences Michael Swann Building, Max Born Crescent Edinburgh EH9 3BF UK
| | - Andrew J Baldwin
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford South Parks Road Oxford OX1 3QZ UK
| | - Julien Michel
- EaStCHEM School of Chemistry, University of Edinburgh David Brewster Road Edinburgh EH9 3FJ UK
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9
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Uversky VN. Protein intrinsic disorder and structure-function continuum. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 166:1-17. [DOI: 10.1016/bs.pmbts.2019.05.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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10
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Abstract
Even after a century of investigation, our understanding of how enzymes work remains far from complete. In particular, several factors that enable enzymes to achieve high catalytic efficiencies remain only poorly understood. A number of theories have been developed, which propose or reaffirm that enzymes work as structural scaffolds, serving to bring together and properly orient the participants so that the reaction can proceed; therefore, leading to enzymes being viewed as only passive participants in the catalyzed reaction. A growing body of evidence shows that enzymes are not rigid structures but are constantly undergoing a wide range of internal motions and conformational fluctuations. In this Perspective, on the basis of studies from our group, we discuss the emerging biophysical model of enzyme catalysis that provides a detailed understanding of the interconnection among internal protein motions, conformational substates, enzyme mechanisms, and the catalytic efficiency of enzymes. For a number of enzymes, networks of conserved residues that extend from the surface of the enzyme all the way to the active site have been discovered. These networks are hypothesized to serve as pathways of energy transfer that enables thermodynamical coupling of the surrounding solvent with enzyme catalysis and play a role in promoting enzyme function. Additionally, the role of enzyme structure and electrostatic effects has been well acknowledged for quite some time. Collectively, the recent knowledge gained about enzyme mechanisms suggests that the conventional paradigm of enzyme structure encoding function is incomplete and needs to be extended to structure encodes dynamics, and together these enzyme features encode function including catalytic rate acceleration.
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Affiliation(s)
- Pratul K Agarwal
- Department of Biochemistry & Cellular and Molecular Biology , University of Tennessee , Knoxville , Tennessee 37996 , United States
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11
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Uversky VN. Flexibility of the "rigid" classics or rugged bottom of the folding funnels of myoglobin, lysozyme, RNase A, chymotrypsin, cytochrome c, and carboxypeptidase A1. INTRINSICALLY DISORDERED PROTEINS 2018; 5:e1355205. [PMID: 30250772 DOI: 10.1080/21690707.2017.1355205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2017] [Accepted: 07/08/2017] [Indexed: 10/18/2022]
Abstract
The abilities to crystalize of a globular protein and to solve its crystal structure seem to represent triumph of the lock-and-key model of protein functionality, where the presence of unique 3D structure resembling aperiodic crystal is considered as a prerequisite for a given protein to possess specific biologic activity. The history of protein crystallography has its roots in first crystal structures of myoglobin, lysozyme, RNase A, chymotrypsin, cytochrome c, and carboxypeptidase A1 solved more than 50 y ago. This article briefly considers extensive structural information currently available for these proteins and shows that the bottoms of their folding funnels (i.e., the lowest parts of their potential energy landscapes) are not smoothed but rugged. In other words, these crystallization classics are characterized by significant conformational flexibility and are not rigid (immobile) crystal-like entities.
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Affiliation(s)
- Vladimir N Uversky
- Department of Molecular Medicine, USF Health Byrd Alzheimer Research Institute, Morsani College of Medicine, University of South Florida, Tampa, FL, USA.,Institute for Biological Instrumentation, Russian Academy of Sciences, Pushchino, Russia
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Basu S, Biswas P. Salt-bridge dynamics in intrinsically disordered proteins: A trade-off between electrostatic interactions and structural flexibility. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:624-641. [DOI: 10.1016/j.bbapap.2018.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/13/2018] [Accepted: 03/07/2018] [Indexed: 12/29/2022]
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13
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Gunasekera B, Abou Diwan C, Altawallbeh G, Kalil H, Maher S, Xu S, Bayachou M. Functional Layer-by-Layer Thin Films of Inducible Nitric Oxide (NO) Synthase Oxygenase and Polyethylenimine: Modulation of Enzyme Loading and NO-Release Activity. ACS APPLIED MATERIALS & INTERFACES 2018; 10:7745-7755. [PMID: 29359547 DOI: 10.1021/acsami.7b17575] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Nitric oxide (NO) release counteracts platelet aggregation and prevents the thrombosis cascade in the inner walls of blood vessels. NO-release coatings also prevent thrombus formation on the surface of blood-contacting medical devices. Our previous work has shown that inducible nitric oxide synthase (iNOS) films release NO fluxes upon enzymatic conversion of the substrate l-arginine. In this work, we report on the modulation of enzyme loading in layer-by-layer (LbL) thin films of inducible nitric oxide synthase oxygenase (iNOSoxy) on polyethylenimine (PEI). The layer of iNOSoxy is electrostatically adsorbed onto the PEI layer. The pH of the iNOSoxy solution affects the amount of enzyme adsorbed. The overall negative surface charge of iNOSoxy in solution depends on the pH and hence determines the density of adsorbed protein on the positively charged PEI layer. We used buffered iNOSoxy solutions adjusted to pHs 8.6 and 7.0, while saline PEI solution was used at pH 7.0. Atomic force microscopy imaging of the outermost layer shows higher protein adsorption with iNOSoxy at pH 8.6 than with a solution of iNOSoxy at pH 7.0. Graphite electrodes with PEI/iNOSoxy films show higher catalytic currents for nitric oxide reduction mediated by iNOSoxy. The higher enzyme loading translates into higher NO flux when the enzyme-modified surface is exposed to a solution containing the substrate and a source of electrons. Spectrophotometric assays showed higher NO fluxes with iNOSoxy/PEI films built at pH 8.6 than with films built at pH 7.0. Fourier transform infrared analysis of iNOSoxy adsorbed on PEI at pH 8.6 and 7.0 shows structural differences of iNOSoxy in films, which explains the observed changes in enzymatic activity. Our findings show that pH provides a strategy to optimize the NOS loading and enzyme activity in NOS-based LbL thin films, which enables improved NO release with minimum layers of PEI/NOS.
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Affiliation(s)
- Bhagya Gunasekera
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Charbel Abou Diwan
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Ghaith Altawallbeh
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Haitham Kalil
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Shaimaa Maher
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
| | - Song Xu
- Keysight Technologies , 1400 Foutaingrove Parkway , Santa Rosa 95403 , California , United States
| | - Mekki Bayachou
- Department of Chemistry , Cleveland State University , 2399 Euclid Avenue SR 397 , Cleveland , Ohio 44120 , United States
- Department of Pathobiology , Lerner Research Institute , The Cleveland Clinic , Cleveland , Ohio 44106 , United States
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14
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Das S, Bhadra P, Ramakumar S, Pal D. Molecular Dynamics Information Improves cis-Peptide-Based Function Annotation of Proteins. J Proteome Res 2017. [PMID: 28633522 DOI: 10.1021/acs.jproteome.7b00217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
cis-Peptide bonds, whose occurrence in proteins is rare but evolutionarily conserved, are implicated to play an important role in protein function. This has led to their previous use in a homology-independent, fragment-match-based protein function annotation method. However, proteins are not static molecules; dynamics is integral to their activity. This is nicely epitomized by the geometric isomerization of cis-peptide to trans form for molecular activity. Hence we have incorporated both static (cis-peptide) and dynamics information to improve the prediction of protein molecular function. Our results show that cis-peptide information alone cannot detect functional matches in cases where cis-trans isomerization exists but 3D coordinates have been obtained for only the trans isomer or when the cis-peptide bond is incorrectly assigned as trans. On the contrary, use of dynamics information alone includes false-positive matches for cases where fragments with similar secondary structure show similar dynamics, but the proteins do not share a common function. Combining the two methods reduces errors while detecting the true matches, thereby enhancing the utility of our method in function annotation. A combined approach, therefore, opens up new avenues of improving existing automated function annotation methodologies.
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Affiliation(s)
- Sreetama Das
- Department of Physics and ‡Department of Computational and Data Sciences, Indian Institute of Science , Bangalore 560012, India
| | - Pratiti Bhadra
- Department of Physics and ‡Department of Computational and Data Sciences, Indian Institute of Science , Bangalore 560012, India
| | - Suryanarayanarao Ramakumar
- Department of Physics and ‡Department of Computational and Data Sciences, Indian Institute of Science , Bangalore 560012, India
| | - Debnath Pal
- Department of Physics and ‡Department of Computational and Data Sciences, Indian Institute of Science , Bangalore 560012, India
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15
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p53 Proteoforms and Intrinsic Disorder: An Illustration of the Protein Structure-Function Continuum Concept. Int J Mol Sci 2016; 17:ijms17111874. [PMID: 27834926 PMCID: PMC5133874 DOI: 10.3390/ijms17111874] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 10/27/2016] [Accepted: 11/03/2016] [Indexed: 01/10/2023] Open
Abstract
Although it is one of the most studied proteins, p53 continues to be an enigma. This protein has numerous biological functions, possesses intrinsically disordered regions crucial for its functionality, can form both homo-tetramers and isoform-based hetero-tetramers, and is able to interact with many binding partners. It contains numerous posttranslational modifications, has several isoforms generated by alternative splicing, alternative promoter usage or alternative initiation of translation, and is commonly mutated in different cancers. Therefore, p53 serves as an important illustration of the protein structure–function continuum concept, where the generation of multiple proteoforms by various mechanisms defines the ability of this protein to have a multitude of structurally and functionally different states. Considering p53 in the light of a proteoform-based structure–function continuum represents a non-canonical and conceptually new contemplation of structure, regulation, and functionality of this important protein.
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16
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Agarwal PK, Doucet N, Chennubhotla C, Ramanathan A, Narayanan C. Conformational Sub-states and Populations in Enzyme Catalysis. Methods Enzymol 2016; 578:273-97. [PMID: 27497171 DOI: 10.1016/bs.mie.2016.05.023] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Enzyme function involves substrate and cofactor binding, precise positioning of reactants in the active site, chemical turnover, and release of products. In addition to formation of crucial structural interactions between enzyme and substrate(s), coordinated motions within the enzyme-substrate complex allow reaction to proceed at a much faster rate, compared to the reaction in solution and in the absence of enzyme. An increasing number of enzyme systems show the presence of conserved protein motions that are important for function. A wide variety of motions are naturally sampled (over femtosecond to millisecond time-scales) as the enzyme complex moves along the energetic landscape, driven by temperature and dynamical events from the surrounding environment. Areas of low energy along the landscape form conformational sub-states, which show higher conformational populations than surrounding areas. A small number of these protein conformational sub-states contain functionally important structural and dynamical features, which assist the enzyme mechanism along the catalytic cycle. Identification and characterization of these higher-energy (also called excited) sub-states and the associated populations are challenging, as these sub-states are very short-lived and therefore rarely populated. Specialized techniques based on computer simulations, theoretical modeling, and nuclear magnetic resonance have been developed for quantitative characterization of these sub-states and populations. This chapter discusses these techniques and provides examples of their applications to enzyme systems.
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Affiliation(s)
- P K Agarwal
- Computational Biology Institute, Oak Ridge National Laboratory, Oak Ridge, TN, United States; University of Tennessee, Knoxville, TN, United States.
| | - N Doucet
- INRS-Institut Armand-Frappier, Université du Québec, Laval, QC, Canada
| | | | - A Ramanathan
- Oak Ridge National Laboratory, Oak Ridge, TN, United States
| | - C Narayanan
- INRS-Institut Armand-Frappier, Université du Québec, Laval, QC, Canada
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17
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Abstract
It is now common knowledge that enzymes are mobile entities relying on complex atomic-scale dynamics and coordinated conformational events for proper ligand recognition and catalysis. However, the exact role of protein dynamics in enzyme function remains either poorly understood or difficult to interpret. This mini-review intends to reconcile biophysical observations and biological significance by first describing a number of common experimental and computational methodologies employed to characterize atomic-scale residue motions on various timescales in enzymes, and second by illustrating how the knowledge of these motions can be used to describe the functional behavior of enzymes and even act upon it. Two biologically relevant examples will be highlighted, namely the HIV-1 protease and DNA polymerase β enzyme systems.
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18
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Gagné D, French RL, Narayanan C, Simonović M, Agarwal PK, Doucet N. Perturbation of the Conformational Dynamics of an Active-Site Loop Alters Enzyme Activity. Structure 2015; 23:2256-2266. [PMID: 26655472 DOI: 10.1016/j.str.2015.10.011] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 10/05/2015] [Accepted: 10/13/2015] [Indexed: 01/28/2023]
Abstract
The role of internal dynamics in enzyme function is highly debated. Specifically, how small changes in structure far away from the reaction site alter protein dynamics and overall enzyme mechanisms is of wide interest in protein engineering. Using RNase A as a model, we demonstrate that elimination of a single methyl group located >10 Å away from the reaction site significantly alters conformational integrity and binding properties of the enzyme. This A109G mutation does not perturb structure or thermodynamic stability, both in the apo and ligand-bound states. However, significant enhancement in conformational dynamics was observed for the bound variant, as probed over nano- to millisecond timescales, resulting in major ligand repositioning. These results illustrate the large effects caused by small changes in structure on long-range conformational dynamics and ligand specificities within proteins, further supporting the importance of preserving wild-type dynamics in enzyme systems that rely on flexibility for function.
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Affiliation(s)
- Donald Gagné
- INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Laval, QC H7V 1B7, Canada
| | - Rachel L French
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 South Ashland, Chicago, IL 60607, USA
| | - Chitra Narayanan
- INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Laval, QC H7V 1B7, Canada
| | - Miljan Simonović
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, 900 South Ashland, Chicago, IL 60607, USA
| | - Pratul K Agarwal
- Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN 37830, USA; Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Nicolas Doucet
- INRS-Institut Armand-Frappier, Université du Québec, 531 Boulevard des Prairies, Laval, QC H7V 1B7, Canada; PROTEO, the Québec Network for Research on Protein Function, Engineering, and Applications, 1045 Avenue de la Médecine, Université Laval, QC G1V 0A6, Canada; GRASP, the Groupe de Recherche Axé sur la Structure des Protéines, 3649 Promenade Sir William Osler, McGill University, Montréal, QC H3G 0B1, Canada.
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19
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Barbany M, Meyer T, Hospital A, Faustino I, D'Abramo M, Morata J, Orozco M, de la Cruz X. Molecular dynamics study of naturally existing cavity couplings in proteins. PLoS One 2015; 10:e0119978. [PMID: 25816327 PMCID: PMC4376744 DOI: 10.1371/journal.pone.0119978] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 01/26/2015] [Indexed: 11/18/2022] Open
Abstract
Couplings between protein sub-structures are a common property of protein dynamics. Some of these couplings are especially interesting since they relate to function and its regulation. In this article we have studied the case of cavity couplings because cavities can host functional sites, allosteric sites, and are the locus of interactions with the cell milieu. We have divided this problem into two parts. In the first part, we have explored the presence of cavity couplings in the natural dynamics of 75 proteins, using 20 ns molecular dynamics simulations. For each of these proteins, we have obtained two trajectories around their native state. After applying a stringent filtering procedure, we found significant cavity correlations in 60% of the proteins. We analyze and discuss the structure origins of these correlations, including neighbourhood, cavity distance, etc. In the second part of our study, we have used longer simulations (≥100 ns) from the MoDEL project, to obtain a broader view of cavity couplings, particularly about their dependence on time. Using moving window computations we explored the fluctuations of cavity couplings along time, finding that these couplings could fluctuate substantially during the trajectory, reaching in several cases correlations above 0.25/0.5. In summary, we describe the structural origin and the variations with time of cavity couplings. We complete our work with a brief discussion of the biological implications of these results.
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Affiliation(s)
- Montserrat Barbany
- Translational Bioinformatics in Neurosciences, Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
| | - Tim Meyer
- Theoretische und computergestützte Biophysik, Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany
| | - Adam Hospital
- Joint IRB (Institute for Research in Biomedicine)—BSC (Barcelona Supercomputing Center) Program on Computational Biology, Barcelona, Spain
| | - Ignacio Faustino
- Joint IRB (Institute for Research in Biomedicine)—BSC (Barcelona Supercomputing Center) Program on Computational Biology, Barcelona, Spain
| | - Marco D'Abramo
- Department of Chemistry, Università degli Studi di Roma "La Sapienza", Roma, Italy
| | - Jordi Morata
- Centre for Research in Agricultural Genomics (CRAG), Barcelona, Spain
| | - Modesto Orozco
- Joint IRB (Institute for Research in Biomedicine)—BSC (Barcelona Supercomputing Center) Program on Computational Biology, Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Xavier de la Cruz
- Translational Bioinformatics in Neurosciences, Vall d'Hebron Research Institute (VHIR), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
- * E-mail:
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20
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Ladani ST, Souffrant MG, Barman A, Hamelberg D. Computational perspective and evaluation of plausible catalytic mechanisms of peptidyl-prolyl cis-trans isomerases. Biochim Biophys Acta Gen Subj 2015; 1850:1994-2004. [PMID: 25585011 DOI: 10.1016/j.bbagen.2014.12.023] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Revised: 12/23/2014] [Accepted: 12/29/2014] [Indexed: 01/16/2023]
Abstract
BACKGROUND Peptidyl prolyl cis-trans isomerization of the protein backbone is involved in the regulation of many biological processes. Cis-trans isomerization is notoriously slow and is catalyzed by a family of cis-trans peptidyl prolyl isomerases (PPIases) that have been implicated in many diseases. A general consensus on how these enzymes speed up prolyl isomerization has not been reached after decades of both experimental and computational studies. SCOPE OF REVIEW Computational studies carried out to understand the catalytic mechanism of the prototypical FK506 binding protein 12, Cyclophilin A and peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) are reviewed. A summary and an evaluation of the implications of the proposed mechanisms from computational studies are presented. MAJOR CONCLUSIONS The analysis of computational studies and evaluation of the proposed mechanisms provide a general consensus and a better understanding of PPIase catalysis. The speedup of the rate of peptidyl-prolyl isomerization by PPIases can be best described by a catalytic mechanism in which the substrate in transition state configuration is stabilized. The enzymes preferentially bind the transition state configuration of the substrate relative to the cis conformation, which in most cases is bound better than the trans conformation of the substrate. Stabilization of the transition state configuration of the substrate leads to a lower free energy barrier and a faster rate of isomerization when compared to the uncatalyzed isomerization reaction. GENERAL SIGNIFICANCE Fully understanding the catalytic mechanism of PPIases has broad implications for drug design, elucidation of the molecular basis of many diseases, protein engineering, and enzyme catalysis in general. This article is part of a Special Issue entitled Proline-directed Foldases: Cell Signaling Catalysts and Drug Targets.
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Affiliation(s)
- Safieh Tork Ladani
- Department of Chemistry and the Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, USA
| | - Michael G Souffrant
- Department of Chemistry and the Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, USA
| | - Arghya Barman
- Department of Chemistry and the Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, USA
| | - Donald Hamelberg
- Department of Chemistry and the Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA 30302-3965, USA.
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21
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Meadows C, Tsang JE, Klinman JP. Picosecond-resolved fluorescence studies of substrate and cofactor-binding domain mutants in a thermophilic alcohol dehydrogenase uncover an extended network of communication. J Am Chem Soc 2014; 136:14821-33. [PMID: 25314615 PMCID: PMC4210157 DOI: 10.1021/ja506667k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Indexed: 01/18/2023]
Abstract
Time-resolved fluorescence dynamics are investigated in two mutants of a thermophilic alcohol dehydrogenase (ht-ADH): Y25A (at the dimer interface) and V260A (at the cofactor-binding domain). These residues, ca. 32 Å apart, are shown to exhibit opposing low-temperature effects on the hydride tunneling step. Using single-tryptophan constructs at the active site (Trp87) and a remote, surface-exposed site (Trp167), time-dependent Stokes shifts and collisional quenching data allow an analysis of intra-protein dynamical communication. A double mutant, Y25A:V260A, was also inserted into each single-Trp construct and analyzed accordingly. None of the mutations affect fluorescence lifetimes, Stokes shift relaxation rates, and quenching data for the surface-exposed Trp167 to an appreciable extent. By contrast, fluorescent probes of the active-site tryptophan 87 reveal distinctive forms of dynamical communication. Stokes shifts show that the distal Y25A increases active-site flexibility, V260A introduces a temperature-dependent equilibration process not previously reported by such measurements, and the double mutant (Y25A:V260A) eliminates the temperature-dependent transition sensed by the active-site tryptophan in the presence of V260A. Collisional quenching data at Trp87 further show a structural change in the active-site environment/solvation for V260A. In the aggregate, the temperature dependencies of the fluorescence data are distinct from the breaks in behavior previously reported for catalysis and hydrogen/deuterium exchange, attributed to time scales for the interconversion of protein conformational substates that are slower and more global than the local motions monitored within. An extended network of dynamical communication between the protein dimer surface and substrate- and cofactor-binding domains emerges from the flourescent data.
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Affiliation(s)
- Corey
W. Meadows
- Department of Chemistry, Department of Molecular and Cell
Biology, and the California
Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
| | - Jonathan E. Tsang
- Department of Chemistry, Department of Molecular and Cell
Biology, and the California
Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
| | - Judith P. Klinman
- Department of Chemistry, Department of Molecular and Cell
Biology, and the California
Institute for Quantitative Biosciences, University of California, Berkeley, California 94720, United States
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22
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Tork Ladani S, Hamelberg D. Intricacies of interactions, dynamics and solvent effects in enzyme catalysis: a computational perspective on cyclophilin A. MOLECULAR SIMULATION 2014. [DOI: 10.1080/08927022.2014.919498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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23
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Abstract
![]()
The Crk adaptor proteins play a central
role as a molecular timer
for the formation of protein complexes including various growth and
differentiation factors. The loss of regulation of Crk results in
many kinds of cancers. A self-regulatory mechanism for Crk was recently
proposed, which involves domain–domain rearrangement. It is
initiated by a cis–trans isomerization of a specific proline
residue (Pro238 in chicken Crk II) and can be accelerated by Cyclophilin
A. To understand how the proline switch controls the autoinhibition
at the molecular level, we performed large-scale molecular dynamics
and metadynamics simulations in the context of short peptides and
multidomain constructs of chicken Crk II. We found that the equilibrium
and kinetic properties of the macrostates are regulated not only by
the local environments of specified prolines but also by the global
organization of multiple domains. We observe the two macrostates (cis
closed/autoinhibited and trans open/uninhibited) consistent with NMR
experiments and predict barriers. We also propose an intermediate
state, the trans closed state, which interestingly was reported to
be a prevalent state in human Crk II. The existence of this macrostate
suggests that the rate of switching off the autoinhibition by Cyp
A may be limited by the relaxation rate of this intermediate state.
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Affiliation(s)
- Junchao Xia
- Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey , 610 Taylor Road, Piscataway, New Jersey 08854, United States
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24
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Ramanathan A, Savol A, Burger V, Chennubhotla CS, Agarwal PK. Protein conformational populations and functionally relevant substates. Acc Chem Res 2014; 47:149-56. [PMID: 23988159 DOI: 10.1021/ar400084s] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Functioning proteins do not remain fixed in a unique structure, but instead they sample a range of conformations facilitated by motions within the protein. Even in the native state, a protein exists as a collection of interconverting conformations driven by thermodynamic fluctuations. Motions on the fast time scale allow a protein to sample conformations in the nearby area of its conformational landscape, while motions on slower time scales give it access to conformations in distal areas of the landscape. Emerging evidence indicates that protein landscapes contain conformational substates with dynamic and structural features that support the designated function of the protein. Nuclear magnetic resonance (NMR) experiments provide information about conformational ensembles of proteins. X-ray crystallography allows researchers to identify the most populated states along the landscape, and computational simulations give atom-level information about the conformational substates of different proteins. This ability to characterize and obtain quantitative information about the conformational substates and the populations of proteins within them is allowing researchers to better understand the relationship between protein structure and dynamics and the mechanisms of protein function. In this Account, we discuss recent developments and challenges in the characterization of functionally relevant conformational populations and substates of proteins. In some enzymes, the sampling of functionally relevant conformational substates is connected to promoting the overall mechanism of catalysis. For example, the conformational landscape of the enzyme dihydrofolate reductase has multiple substates, which facilitate the binding and the release of the cofactor and substrate and catalyze the hydride transfer. For the enzyme cyclophilin A, computational simulations reveal that the long time scale conformational fluctuations enable the enzyme to access conformational substates that allow it to attain the transition state, therefore promoting the reaction mechanism. In the long term, this emerging view of proteins with conformational substates has broad implications for improving our understanding of enzymes, enzyme engineering, and better drug design. Researchers have already used photoactivation to modulate protein conformations as a strategy to develop a hypercatalytic enzyme. In addition, the alteration of the conformational substates through binding of ligands at locations other than the active site provides the basis for the design of new medicines through allosteric modulation.
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Affiliation(s)
- Arvind Ramanathan
- Computational Science and Engineering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Andrej Savol
- Joint Carnegie Mellon University−University of Pittsburgh Ph.D Program in Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Virginia Burger
- Joint Carnegie Mellon University−University of Pittsburgh Ph.D Program in Computational Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Chakra S. Chennubhotla
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pratul K. Agarwal
- Annavitas Biosciences, 2519 Caspian Drive, Knoxville, Tennessee 37932, United States
- Computational Biology Institute, and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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25
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McGowan LC, Hamelberg D. Conformational plasticity of an enzyme during catalysis: intricate coupling between cyclophilin A dynamics and substrate turnover. Biophys J 2013; 104:216-26. [PMID: 23332074 DOI: 10.1016/j.bpj.2012.11.3815] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 11/25/2012] [Accepted: 11/27/2012] [Indexed: 01/15/2023] Open
Abstract
Enzyme catalysis is central to almost all biochemical processes, speeding up rates of reactions to biological relevant timescales. Enzymes make use of a large ensemble of conformations in recognizing their substrates and stabilizing the transition states, due to the inherent dynamical nature of biomolecules. The exact role of these diverse enzyme conformations and the interplay between enzyme conformational dynamics and catalysis is, according to the literature, not well understood. Here, we use molecular dynamics simulations to study human cyclophilin A (CypA), in order to understand the role of enzyme motions in the catalytic mechanism and recognition. Cyclophilin A is a tractable model system to study using classical simulation methods, because catalysis does not involve bond formation or breakage. We show that the conformational dynamics of active site residues of substrate-bound CypA is inherent in the substrate-free enzyme. CypA interacts with its substrate via conformational selection as the configurations of the substrate changes during catalysis. We also show that, in addition to tight intermolecular hydrophobic interactions between CypA and the substrate, an intricate enzyme-substrate intermolecular hydrogen-bonding network is extremely sensitive to the configuration of the substrate. These enzyme-substrate intermolecular interactions are loosely formed when the substrate is in the reactant and product states and become well formed and reluctant to break when the substrate is in the transition state. Our results clearly suggest coupling among enzyme-substrate intermolecular interactions, the dynamics of the enzyme, and the chemical step. This study provides further insights into the mechanism of peptidyl-prolyl cis/trans isomerases and the general interplay between enzyme conformational dynamics and catalysis.
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Affiliation(s)
- Lauren C McGowan
- Department of Chemistry and the Center for Biotechnology and Drug Design, Georgia State University, Atlanta, Georgia, USA
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26
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Unusual biophysics of intrinsically disordered proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1834:932-51. [PMID: 23269364 DOI: 10.1016/j.bbapap.2012.12.008] [Citation(s) in RCA: 409] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 11/21/2012] [Accepted: 12/12/2012] [Indexed: 02/08/2023]
Abstract
Research of a past decade and a half leaves no doubt that complete understanding of protein functionality requires close consideration of the fact that many functional proteins do not have well-folded structures. These intrinsically disordered proteins (IDPs) and proteins with intrinsically disordered protein regions (IDPRs) are highly abundant in nature and play a number of crucial roles in a living cell. Their functions, which are typically associated with a wide range of intermolecular interactions where IDPs possess remarkable binding promiscuity, complement functional repertoire of ordered proteins. All this requires a close attention to the peculiarities of biophysics of these proteins. In this review, some key biophysical features of IDPs are covered. In addition to the peculiar sequence characteristics of IDPs these biophysical features include sequential, structural, and spatiotemporal heterogeneity of IDPs; their rough and relatively flat energy landscapes; their ability to undergo both induced folding and induced unfolding; the ability to interact specifically with structurally unrelated partners; the ability to gain different structures at binding to different partners; and the ability to keep essential amount of disorder even in the bound form. IDPs are also characterized by the "turned-out" response to the changes in their environment, where they gain some structure under conditions resulting in denaturation or even unfolding of ordered proteins. It is proposed that the heterogeneous spatiotemporal structure of IDPs/IDPRs can be described as a set of foldons, inducible foldons, semi-foldons, non-foldons, and unfoldons. They may lose their function when folded, and activation of some IDPs is associated with the awaking of the dormant disorder. It is possible that IDPs represent the "edge of chaos" systems which operate in a region between order and complete randomness or chaos, where the complexity is maximal. This article is part of a Special Issue entitled: The emerging dynamic view of proteins: Protein plasticity in allostery, evolution and self-assembly.
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27
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Koyama M, Nishimasu H, Ishitani R, Nureki O. Molecular Dynamics Simulation of Autotaxin: Roles of the Nuclease-like Domain and the Glycan Modification. J Phys Chem B 2012; 116:11798-808. [DOI: 10.1021/jp303198u] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Michio Koyama
- Department of Biophysics and
Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032,
Japan
| | - Hiroshi Nishimasu
- Department of Biophysics and
Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032,
Japan
| | - Ryuichiro Ishitani
- Department of Biophysics and
Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032,
Japan
- RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198,
Japan
| | - Osamu Nureki
- Department of Biophysics and
Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032,
Japan
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28
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Muzykantov VR, Radhakrishnan R, Eckmann DM. Dynamic factors controlling targeting nanocarriers to vascular endothelium. Curr Drug Metab 2012; 13:70-81. [PMID: 22292809 DOI: 10.2174/138920012798356916] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 03/05/2011] [Accepted: 04/15/2011] [Indexed: 12/22/2022]
Abstract
Endothelium lining the luminal surface of blood vessels is the key target and barrier for vascular drug delivery. Nanocarriers coated with antibodies or affinity peptides that bind specifically to endothelial surface determinants provide targeted delivery of therapeutic cargoes to these cells. Endothelial targeting consists of several phases including circulation in the bloodstream, anchoring on the endothelial surface and, in some cases, intracellular uptake and trafficking of the internalized materials. Dynamic parameters of the vasculature including the blood hydrodynamics as well as surface density, accessibility, membrane mobility and clustering of target determinants modulate these phases of the targeting, especially anchoring to endothelium. Further, such controlled parameters of design of drug nanocarriers such as affinity, surface density and epitope specificity of targeting antibodies, carrier size and shape also modulate endothelial targeting and resultant sub-cellular addressing. This article reviews experimental and computational approaches for analysis of factors modulating targeting nanocarriers to the endothelial cells.
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29
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Resolving the complex role of enzyme conformational dynamics in catalytic function. Proc Natl Acad Sci U S A 2012; 109:5699-704. [PMID: 22451902 DOI: 10.1073/pnas.1117060109] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Despite growing evidence suggesting the importance of enzyme conformational dynamics (ECD) in catalysis, a consensus on how precisely ECD influences the chemical step and reaction rates is yet to be reached. Here, we characterize ECD in Cyclophilin A, a well-studied peptidyl-prolyl cis-trans isomerase, using normal and accelerated, atomistic molecular dynamics simulations. Kinetics and free energy landscape of the isomerization reaction in solution and enzyme are explored in unconstrained simulations by allowing significantly lower torsional barriers, but in no way compromising the atomistic description of the system or the explicit solvent. We reveal that the reaction dynamics is intricately coupled to enzymatic motions that span multiple timescales and the enzyme modes are selected based on the energy barrier of the chemical step. We show that Kramers' rate theory can be used to present a clear rationale of how ECD affects the reaction dynamics and catalytic rates. The effects of ECD can be incorporated into the effective diffusion coefficient, which we estimate to be about ten times slower in enzyme than in solution. ECD thereby alters the preexponential factor, effectively impeding the rate enhancement. From our analyses, the trend observed for lower torsional barriers can be extrapolated to actual isomerization barriers, allowing successful prediction of the speedup in rates in the presence of CypA, which is in notable agreement with experimental estimates. Our results further reaffirm transition state stabilization as the main effect in enhancing chemical rates and provide a unified view of ECD's role in catalysis from an atomistic perspective.
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30
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Evolutionarily conserved linkage between enzyme fold, flexibility, and catalysis. PLoS Biol 2011; 9:e1001193. [PMID: 22087074 PMCID: PMC3210774 DOI: 10.1371/journal.pbio.1001193] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 09/27/2011] [Indexed: 11/19/2022] Open
Abstract
Proteins are intrinsically flexible molecules. The role of internal motions in a protein's designated function is widely debated. The role of protein structure in enzyme catalysis is well established, and conservation of structural features provides vital clues to their role in function. Recently, it has been proposed that the protein function may involve multiple conformations: the observed deviations are not random thermodynamic fluctuations; rather, flexibility may be closely linked to protein function, including enzyme catalysis. We hypothesize that the argument of conservation of important structural features can also be extended to identification of protein flexibility in interconnection with enzyme function. Three classes of enzymes (prolyl-peptidyl isomerase, oxidoreductase, and nuclease) that catalyze diverse chemical reactions have been examined using detailed computational modeling. For each class, the identification and characterization of the internal protein motions coupled to the chemical step in enzyme mechanisms in multiple species show identical enzyme conformational fluctuations. In addition to the active-site residues, motions of protein surface loop regions (>10 Å away) are observed to be identical across species, and networks of conserved interactions/residues connect these highly flexible surface regions to the active-site residues that make direct contact with substrates. More interestingly, examination of reaction-coupled motions in non-homologous enzyme systems (with no structural or sequence similarity) that catalyze the same biochemical reaction shows motions that induce remarkably similar changes in the enzyme–substrate interactions during catalysis. The results indicate that the reaction-coupled flexibility is a conserved aspect of the enzyme molecular architecture. Protein motions in distal areas of homologous and non-homologous enzyme systems mediate similar changes in the active-site enzyme–substrate interactions, thereby impacting the mechanism of catalyzed chemistry. These results have implications for understanding the mechanism of allostery, and for protein engineering and drug design.
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31
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Velazquez HA, Hamelberg D. Conformational Selection in the Recognition of Phosphorylated Substrates by the Catalytic Domain of Human Pin1. Biochemistry 2011; 50:9605-15. [DOI: 10.1021/bi2009954] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Hector A. Velazquez
- Department of Chemistry and Center
for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098, United States
| | - Donald Hamelberg
- Department of Chemistry and Center
for Biotechnology
and Drug Design, Georgia State University, Atlanta, Georgia 30302-4098, United States
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32
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Borreguero JM, He J, Meilleur F, Weiss KL, Brown CM, Myles DA, Herwig KW, Agarwal PK. Redox-promoting protein motions in rubredoxin. J Phys Chem B 2011; 115:8925-36. [PMID: 21608980 DOI: 10.1021/jp201346x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proteins are dynamic objects, constantly undergoing conformational fluctuations, yet the linkage between internal protein motion and function is widely debated. This study reports on the characterization of temperature-activated collective and individual atomic motions of oxidized rubredoxin, a small 53 residue protein from thermophilic Pyrococcus furiosus (RdPf). Computational modeling allows detailed investigations of protein motions as a function of temperature, and neutron scattering experiments are used to compare to computational results. Just above the dynamical transition temperature which marks the onset of significant anharmonic motions of the protein, the computational simulations show both a significant reorientation of the average electrostatic force experienced by the coordinated Fe(3+) ion and a dramatic rise in its strength. At higher temperatures, additional anharmonic modes become activated and dominate the electrostatic fluctuations experienced by the ion. At 360 K, close to the optimal growth temperature of P. furiosus, simulations show that three anharmonic modes including motions of two conserved residues located at the protein active site (Ile7 and Ile40) give rise to the majority of the electrostatic fluctuations experienced by the Fe(3+) ion. The motions of these residues undergo displacements which may facilitate solvent access to the ion.
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Affiliation(s)
- Jose M Borreguero
- Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
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33
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Ramanathan A, Savol AJ, Langmead CJ, Agarwal PK, Chennubhotla CS. Discovering conformational sub-states relevant to protein function. PLoS One 2011; 6:e15827. [PMID: 21297978 PMCID: PMC3030567 DOI: 10.1371/journal.pone.0015827] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 11/25/2010] [Indexed: 11/23/2022] Open
Abstract
Background Internal motions enable proteins to explore a range of conformations, even in the vicinity of native state. The role of conformational fluctuations in the designated function of a protein is widely debated. Emerging evidence suggests that sub-groups within the range of conformations (or sub-states) contain properties that may be functionally relevant. However, low populations in these sub-states and the transient nature of conformational transitions between these sub-states present significant challenges for their identification and characterization. Methods and Findings To overcome these challenges we have developed a new computational technique, quasi-anharmonic analysis (QAA). QAA utilizes higher-order statistics of protein motions to identify sub-states in the conformational landscape. Further, the focus on anharmonicity allows identification of conformational fluctuations that enable transitions between sub-states. QAA applied to equilibrium simulations of human ubiquitin and T4 lysozyme reveals functionally relevant sub-states and protein motions involved in molecular recognition. In combination with a reaction pathway sampling method, QAA characterizes conformational sub-states associated with cis/trans peptidyl-prolyl isomerization catalyzed by the enzyme cyclophilin A. In these three proteins, QAA allows identification of conformational sub-states, with critical structural and dynamical features relevant to protein function. Conclusions Overall, QAA provides a novel framework to intuitively understand the biophysical basis of conformational diversity and its relevance to protein function.
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Affiliation(s)
- Arvind Ramanathan
- Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
- Lane Center for Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Andrej J. Savol
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Joint Carnegie Mellon University–University of Pittsburgh Ph.D. Program in Computational Biology, Pittsburgh, Pennsylvania, United States of America
| | - Christopher J. Langmead
- Computer Science Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
- Lane Center for Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America
| | - Pratul K. Agarwal
- Computational Biology Institute and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
- * E-mail: (PKA); (CSC)
| | - Chakra S. Chennubhotla
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (PKA); (CSC)
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Pineda JET, Antoniou D, Schwartz SD. Slow conformational motions that favor sub-picosecond motions important for catalysis. J Phys Chem B 2010; 114:15985-90. [PMID: 21077591 PMCID: PMC3018068 DOI: 10.1021/jp1071296] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It has been accepted for many years that functionally important motions are crucial to binding properties of ligands in such molecules as hemoglobin and myoglobin. In enzymatic reactions, theory and now experiment are beginning to confirm the importance of motions on a fast (ps) time scale in the chemical step of the catalytic process. What is missing is a clear physical picture of how slow conformational fluctuations are related to the fast motions that have been identified as crucial. This paper presents a theoretical analysis of this issue for human heart lactate dehydrogenase. We will examine how slow conformational motions bring the system to conformations that are distinguished as catalytically competent because they favor specific fast motions.
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Affiliation(s)
- J.R. Exequiel T. Pineda
- Dept of Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA
| | - Dimitri Antoniou
- Dept of Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA
| | - Steven D. Schwartz
- Dept of Biophysics, Albert Einstein College of Medicine, 1300 Morris Park Ave, Bronx, NY 10461, USA
- Dept of Biochemistry, Albert Einstein College of Medicine, 91440 Bures-sur-Yvette, France
- Institut des Hautes Études Scientifiques, 91440 Bures-sur-Yvette, France
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35
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Kamath G, Howell EE, Agarwal PK. The Tail Wagging the Dog: Insights into Catalysis in R67 Dihydrofolate Reductase. Biochemistry 2010; 49:9078-88. [DOI: 10.1021/bi1007222] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ganesh Kamath
- Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
| | - Elizabeth E. Howell
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996
| | - Pratul K. Agarwal
- Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
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36
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Hu X, Zhang W, Carmichael I, Serianni AS. Amide cis-trans isomerization in aqueous solutions of methyl N-formyl-D-glucosaminides and methyl N-acetyl-D-glucosaminides: chemical equilibria and exchange kinetics. J Am Chem Soc 2010; 132:4641-52. [PMID: 20225805 DOI: 10.1021/ja9086787] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amide cis-trans isomerization (CTI) in methyl 2-deoxy-2-acylamido-d-glucopyranosides was investigated by (1)H and (13)C NMR spectroscopy. Singly (13)C-labeled methyl 2-deoxy-2-formamido-d-glucopyranoside (MeGlcNFm) anomers provided standard (1)H and (13)C chemical shifts and (1)H-(1)H and (13)C-(13)C spin-coupling constants for cis and trans amides that are detected readily in aqueous solution. Equipped with this information, doubly (13)C-labeled methyl 2-deoxy-2-acetamido-d-glucopyranoside (MeGlcNAc) anomers were investigated, leading to the detection and quantification of cis and trans amides in this biologically important aminosugar. In comparison to MeGlcNFm anomers, the percentage of cis amide in aqueous solutions of MeGlcNAc anomers is small ( approximately 23% for MeGlcNFm versus approximately 1.8% for MeGlcNAc at 42 degrees C) but nevertheless observable with assistance from (13)C-labeling. Temperature studies gave thermodynamic parameters DeltaG degrees , DeltaH degrees , and DeltaS degrees for cis-trans interconversion in MeGlcNFm and MeGlcNAc anomers. Cis/trans equilibria depended on anomeric configuration, with solutions of alpha-anomers containing less cis amide than those of beta-anomers. Confirmation of the presence of cis amide in MeGlcNAc solutions derived from quantitative (13)C saturation transfer measurements of CTI rate constants as a function of solution temperature, yielding activation parameters E(act), DeltaG degrees (), DeltaH degrees (), and DeltaS degrees () for saccharide CTI. Rate constants for the conversion of trans to cis amide in MeGlcNFm and MeGlcNAc anomers ranged from 0.02 to 3.59 s(-1) over 31-85 degrees C, compared to 0.24-80 s(-1) for the conversion of cis to trans amide over the same temperature range. Energies of activation ranged from 16-19 and 19-20 kcal/mol for the cis --> trans and trans --> cis processes, respectively. Complementary DFT calculations on MeGlcNFm and MeGlcNAc model structures were conducted to evaluate the effects of an acyl side chain and anomeric structure, as well as C2-N2 bond rotation, on CTI energetics. These studies show that aqueous solutions of GlcNAc-containing structures contain measurable amounts of both cis and trans amides, which may influence their biological properties.
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Affiliation(s)
- Xiaosong Hu
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA
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37
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Ramanathan A, Agarwal PK, Kurnikova M, Langmead CJ. An online approach for mining collective behaviors from molecular dynamics simulations. J Comput Biol 2010; 17:309-24. [PMID: 20377447 DOI: 10.1089/cmb.2009.0167] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Collective behavior involving distally separate regions in a protein is known to widely affect its function. In this article, we present an online approach to study and characterize collective behavior in proteins as molecular dynamics (MD) simulations progress. Our representation of MD simulations as a stream of continuously evolving data allows us to succinctly capture spatial and temporal dependencies that may exist and analyze them efficiently using data mining techniques. By using tensor analysis we identify (a) collective motions (i.e., dynamic couplings) and (b) time-points during the simulation where the collective motions suddenly change. We demonstrate the applicability of this method on two different protein simulations for barnase and cyclophilin A. We characterize the collective motions in these proteins using our method and analyze sudden changes in these motions. Taken together, our results indicate that tensor analysis is well suited to extracting information from MD trajectories in an online fashion.
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Affiliation(s)
- Arvind Ramanathan
- Lane Center for Computational Biology, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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38
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Ramanathan A, Agarwal PK. Computational identification of slow conformational fluctuations in proteins. J Phys Chem B 2009; 113:16669-80. [PMID: 19908896 PMCID: PMC2872677 DOI: 10.1021/jp9077213] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Conformational flexibility of proteins has been linked to their designated functions. Slow conformational fluctuations occurring at the microsecond to millisecond time scale, in particular, have recently attracted considerable interest in connection to the mechanism of enzyme catalysis. Computational methods are providing valuable insights into the connection between protein structure, flexibility, and function. In this report, we present studies on identification and characterization of microsecond flexibility of ubiquitin, based on quasi-harmonic analysis (QHA) and normal-mode analysis (NMA). The results indicate that the slowest 10 QHA modes, computed from the 0.5 mus molecular dynamics ensemble, contribute over 78% of all motions. The identified slow movements show over 75% similarity with the conformational fluctuations observed in nuclear magnetic resonance ensemble and also agree with displacements in the set of X-ray structures. The slowest modes show high flexibility in the beta1-beta2, alpha1-beta3, and beta3-beta4 loop regions, with functional implications in the mechanism of binding other proteins. NMA of ubiquitin structures was not able to reproduce the long time scale fluctuations, as they were found to strongly depend on the reference structures. Further, conformational fluctuations coupled to the cis/trans isomerization reaction catalyzed by the enzyme cyclophilin A (CypA), occurring at the microsecond to millisecond time scale, have also been identified and characterized on the basis of QHA of conformations sampled along the reaction pathway. The results indicate that QHA covers the same conformational landscape as the experimentally observed CypA flexibility. Overall, the identified slow conformational fluctuations in ubiquitin and CypA indicate that the intrinsic flexibility of these proteins is closely linked to their designated functions.
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Affiliation(s)
- Arvind Ramanathan
- Joint Carnegie Mellon University-University of Pittsburgh Ph.D. Program in Computational Biology, Lane Center for Computational Biology, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213
- Computational Biology Institute, and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Pratul K. Agarwal
- Computational Biology Institute, and Computer Science and Mathematics Division, Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge, TN 37831
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39
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Moparthi SB, Hammarström P, Carlsson U. A nonessential role for Arg 55 in cyclophilin18 for catalysis of proline isomerization during protein folding. Protein Sci 2009; 18:475-9. [PMID: 19185003 DOI: 10.1002/pro.28] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The protein folding process is often in vitro rate-limited by slow cis-trans proline isomerization steps. Importantly, the rate of this process in vivo is accelerated by prolyl isomerases (PPIases). The archetypal PPIase is the human cyclophilin 18 (Cyp18 or CypA), and Arg 55 has been demonstrated to play a crucial role when studying short peptide substrates in the catalytic action of Cyp18 by stabilizing the transition state of isomerization. However, in this study we show that a R55A mutant of Cyp18 is as efficient as the wild type to accelerate the refolding reaction of human carbonic anhydrase II (HCA II). Thus, it is evident that the active-site located Arg 55 is not required for catalysis of the rate-limiting prolyl cis-trans isomerization steps during the folding of a protein substrate as HCA II. Nevertheless, catalysis of cis-trans proline isomerization in HCA II occurs in the active-site of Cyp18, since binding of the inhibitor cyclosporin A abolishes rate acceleration of the refolding reaction. Obviously, the catalytic mechanisms of Cyp18 can differ when acting upon a simple model peptide, four residues long, with easily accessible Pro residues compared with a large protein molecule undergoing folding with partly or completely buried Pro residues. In the latter case, the isomerization kinetics are significantly slower and simpler mechanistic factors such as desolvation and/or strain might operate during folding-assisted catalysis, since binding to the hydrophobic active site is still a prerequisite for catalysis.
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40
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Mechanism of action of cyclophilin a explored by metadynamics simulations. PLoS Comput Biol 2009; 5:e1000309. [PMID: 19282959 PMCID: PMC2643488 DOI: 10.1371/journal.pcbi.1000309] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 01/28/2009] [Indexed: 11/22/2022] Open
Abstract
Trans/cis prolyl isomerisation is involved in several biological processes, including the development of numerous diseases. In the HIV-1 capsid protein (CA), such a process takes place in the uncoating and recruitment of the virion and is catalyzed by cyclophilin A (CypA). Here, we use metadynamics simulations to investigate the isomerization of CA's model substrate HAGPIA in water and in its target protein CypA. Our results allow us to propose a novel mechanistic hypothesis, which is finally consistent with all of the available molecular biology data. Peptidyl prolyl isomerases are ubiquitous enzymes whose actions are crucial in several biological processes, such as, for instance, in cellular signalling and in the onset of several diseases, e.g., HIV infection. Therefore, these isomerases are promising targets for the design of new drugs. For this purpose, we need to understand their molecular mechanism of action. One of the most characterized peptidyl prolyl isomerases is cyclophilin A. Previous studies characterized the roles of several protein regions in isomerase function. However, there are still experimentally identified important portions of the protein whose specific actions in the mechanism are still not known. Here, we address this problem by an extensive computational study of cyclophilin A and a substrate peptide that is part of the HIV-1 capside protein. We present a novel four-step mechanism of the whole enzymatic process, which is consistent with all of the available experimental data. Moreover, these steps can be used as targets for the development of drugs, e.g., for HIV-1 infection.
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41
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Liu YH, Konermann L. Conformational dynamics of free and catalytically active thermolysin are indistinguishable by hydrogen/deuterium exchange mass spectrometry. Biochemistry 2008; 47:6342-51. [PMID: 18494500 DOI: 10.1021/bi800463q] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Conformational dynamics are thought to be a prerequisite for the catalytic activity of enzymes. However, the exact relationship between structural fluctuations and function is not well understood. In this work hydrogen/deuterium exchange (HDX) and electrospray ionization mass spectrometry (ESI-MS) are used for exploring the conformational dynamics of thermolysin. Amide HDX reflects the internal mobility of proteins; regions that undergo frequent unfolding-refolding show faster exchange than segments that are highly stable. Thermolysin is a zinc protease with an active site that is located between two lobes. Substrate turnover is associated with hinge bending that leads to a closed conformation. Product release regenerates the open form, such that steady-state catalysis involves a continuous closing/opening cycle. HDX/ESI-MS with proteolytic peptide mapping in the absence of substrate shows that elements in the periphery of the two lobes are most mobile. A comparison with previous X-ray data suggests that these peripheral regions undergo quite pronounced structural changes during the catalytic cycle. In contrast, active site residues exhibit only a moderate degree of backbone flexibility, and the central zinc appears to be in a fairly rigid environment. The presence of both rigid and moderately flexible elements in the active site may reflect a carefully tuned balance that is required for function. Interestingly, the HDX behavior of catalytically active thermolysin is indistinguishable from that of the free enzyme. This result is consistent with the view that catalytically relevant motions preexist in the resting state and that enzyme function can only be performed within the limitations given by the intrinsic dynamics of the protein. The data presented in this work indicate the prevalence of stochastic elements in the function of thermolysin, rather than supporting a deterministic mechanism.
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Affiliation(s)
- Yu-Hong Liu
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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42
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Galat A. Functional drift of sequence attributes in the FK506-binding proteins (FKBPs). J Chem Inf Model 2008; 48:1118-30. [PMID: 18412331 DOI: 10.1021/ci700429n] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Diverse members of the FK506-binding proteins (FKBPs) group and their complexes with different macrocyclic ligands of fungal origins such as FK506, rapamycin, ascomycin, and their immunosuppressive and nonimmunosuppressive derivatives display a variety of cellular and biological activities. The functional relatedness of the FKBPs was estimated from the following attributes of their aligned sequences: 1 degrees conservation of the consensus sequence; 2 degrees sequence similarity; 3 degrees pI; 4 degrees hydrophobicity; 5 degrees amino acid hydrophobicity and bulkiness profiles. Analyses of the multiple sequence alignments and intramolecular interaction networks calculated from a series of structures of the FKBPs revealed some variations in the interaction clusters formed by the AA residues that are crucial for sustaining peptidylprolyl cis/trans isomerases (PPIases) activity and binding capacity of the FKBPs. Fine diversification of the sequences of the multiple paralogues and orthologues of the FKBPs encoded in different genomes alter the intramolecular interaction patterns of their structures and allowed them to gain some selectivity in binding to diverse targets (functional drift).
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Affiliation(s)
- Andrzej Galat
- Institute de Biologie et de Technologies de Saclay, DSV/CEA, CE-Saclay, F-91191 Gif-sur-Yvette Cedex, France.
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43
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Affiliation(s)
- David D Boehr
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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44
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Radhakrishnan R. Coupling of fast and slow modes in the reaction pathway of the minimal hammerhead ribozyme cleavage. Biophys J 2007; 93:2391-9. [PMID: 17545240 PMCID: PMC1965431 DOI: 10.1529/biophysj.107.104661] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
By employing classical molecular dynamics, correlation analysis of coupling between slow and fast dynamical modes, and free energy (umbrella) sampling using classical as well as mixed quantum mechanics molecular mechanics force fields, we uncover a possible pathway for phosphoryl transfer in the self-cleaving reaction of the minimal hammerhead ribozyme. The significance of this pathway is that it initiates from the minimal hammerhead crystal structure and describes the reaction landscape as a conformational rearrangement followed by a covalent transformation. The delineated mechanism is catalyzed by two metal (Mg(2+)) ions, proceeds via an in-line-attack by CYT 17 O2' on the scissile phosphorous (ADE 1.1 P), and is therefore consistent with the experimentally observed inversion configuration. According to the delineated mechanism, the coupling between slow modes involving the hammerhead backbone with fast modes in the cleavage site appears to be crucial for setting up the in-line nucleophilic attack.
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Affiliation(s)
- Ravi Radhakrishnan
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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45
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Doucet N, Savard PY, Pelletier JN, Gagné SM. NMR investigation of Tyr105 mutants in TEM-1 beta-lactamase: dynamics are correlated with function. J Biol Chem 2007; 282:21448-59. [PMID: 17426035 DOI: 10.1074/jbc.m609777200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The existence of coupled residue motions on various time scales in enzymes is now well accepted, and their detailed characterization has become an essential element in understanding the role of dynamics in catalysis. To this day, a handful of enzyme systems has been shown to rely on essential residue motions for catalysis, but the generality of such phenomena remains to be elucidated. Using NMR spectroscopy, we investigated the electronic and dynamic effects of several mutations at position 105 in TEM-1 beta-lactamase, an enzyme responsible for antibiotic resistance. Even in absence of substrate, our results show that the number and magnitude of short and long range effects on (1)H-(15)N chemical shifts are correlated with the catalytic efficiencies of the various Y105X mutants investigated. In addition, (15)N relaxation experiments on mutant Y105D show that several active-site residues of TEM-1 display significantly altered motions on both picosecond-nanosecond and microsecond-millisecond time scales despite many being far away from the site of mutation. The altered motions among various active-site residues in mutant Y105D may account for the observed decrease in catalytic efficiency, therefore suggesting that short and long range residue motions could play an important catalytic role in TEM-1 beta-lactamase. These results support previous observations suggesting that internal motions play a role in promoting protein function.
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Affiliation(s)
- Nicolas Doucet
- Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7
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46
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Trzesniak D, van Gunsteren WF. Catalytic mechanism of cyclophilin as observed in molecular dynamics simulations: pathway prediction and reconciliation of X-ray crystallographic and NMR solution data. Protein Sci 2007; 15:2544-51. [PMID: 17075133 PMCID: PMC2242407 DOI: 10.1110/ps.062356406] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Cyclophilins are proteins that catalyze X-proline cis-trans interconversion, where X represents any amino acid. Its mechanism of action has been investigated over the past years but still generates discussion, especially because until recently structures of the ligand in the cis and trans conformations for the same system were lacking. X-ray crystallographic structures for the complex cyclophilin A and HIV-1 capsid mutants with ligands in the cis and trans conformations suggest a mechanism where the N-terminal portion of the ligand rotates during the cis-trans isomerization. However, a few years before, a C-terminal rotating ligand was proposed to explain NMR solution data. In the present study we use molecular dynamics (MD) simulations to generate a trans structure starting from the cis structure. From simulations starting from the cis and trans structures obtained through the rotational pathways, the seeming contradiction between the two sets of experimental data could be resolved. The simulated N-terminal rotated trans structure shows good agreement with the equivalent crystal structure and, moreover, is consistent with the NMR data. These results illustrate the use of MD simulation at atomic resolution to model structural transitions and to interpret experimental data.
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Affiliation(s)
- Daniel Trzesniak
- Laboratory of Physical Chemistry, Swiss Federal Institute of Technology Zürich, ETH, CH-8093 Zürich, Switzerland
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47
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Langer AK, Poon HF, Münch G, Lynn BC, Arendt T, Butterfield DA. Identification of AGE-modified proteins in SH-SY5Y and OLN-93 Cells. Neurotox Res 2006; 9:255-68. [PMID: 16782585 DOI: 10.1007/bf03033316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The formation of "Advanced Glycation End products" (AGEs) is an inevitable consequence of mammalian glucose metabolism. AGE-mediated protein-protein crosslinks lead to detergent-insoluble and protease-resistant protein aggregates, and in Alzheimer's disease (AD) extra cellular senile plaques (SPs) and intracellular neurofibrillary tangles (NFTs) have been shown to contain AGEs. However, to date little is known concerning the most prevalent protein-targets of AGE modification under normal, non-pathological conditions. Here, a combination of 2D-electrophoresis, Western blotting and mass spectrometry has been used to identify preferentially AGE-modified proteins in oligodendrocyte (OLN-93) and neuroblastoma cell lines (SH-SY5Y) in standard culture. Proteomics analysis identified a total of eight targets with structural, metabolic and regulatory function, three of which (beta-actin, beta-tubulin and eukaryotic Elongation Factor 1-alpha) were common to both cell lines. Based on results from prior studies, modification of these proteins may lead to a loss of function. Consequently, the identification of targets for these proteins is of particular interest for a better understanding of the consequences of AGE-modification in aging, neurodegenerative diseases and diabetes.
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Affiliation(s)
- André K Langer
- Nachwuchsgruppe 1, Interdisciplinary Centre of Clinical Research (IZKF), University of Leipzig, 04103 Leipzig, Germany.
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48
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Agarwal PK, Alam SR. Biomolecular simulations on petascale: promises and challenges. ACTA ACUST UNITED AC 2006. [DOI: 10.1088/1742-6596/46/1/046] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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49
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Liu YH, Konermann L. Enzyme conformational dynamics during catalysis and in the ‘resting state’ monitored by hydrogen/deuterium exchange mass spectrometry. FEBS Lett 2006; 580:5137-42. [PMID: 16963025 DOI: 10.1016/j.febslet.2006.08.042] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2006] [Revised: 08/11/2006] [Accepted: 08/17/2006] [Indexed: 10/24/2022]
Abstract
This work reports the use of electrospray mass spectrometry for studying the conformational dynamics of enzymes by amide hydrogen/deuterium exchange (HDX) measurements. A rapid-mixing quench-flow approach allows comparisons to be made between the HDX kinetics of free enzymes with those under steady-state conditions. Experiments carried out on carboxypeptidase B in the absence of substrate and in the presence of saturating concentrations of hippuryl-Arg result in HDX kinetics that are indistinguishable. This finding implies that the conformational dynamics that mediate HDX are not significantly different in the resting state of the enzyme and during substrate turnover.
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Affiliation(s)
- Yu-Hong Liu
- Department of Chemistry, The University of Western Ontario, London, Ont., Canada N6A 5B7
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Pu J, Gao J, Truhlar DG. Multidimensional tunneling, recrossing, and the transmission coefficient for enzymatic reactions. Chem Rev 2006; 106:3140-69. [PMID: 16895322 PMCID: PMC4478620 DOI: 10.1021/cr050308e] [Citation(s) in RCA: 288] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Jingzhi Pu
- Department of Chemistry and Supercomputer Institute, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, Minnesota 55455-0431
| | - Jiali Gao
- Department of Chemistry and Supercomputer Institute, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, Minnesota 55455-0431
| | - Donald G. Truhlar
- Department of Chemistry and Supercomputer Institute, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, Minnesota 55455-0431
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