1
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Tesei G, Martins JM, Kunze MBA, Wang Y, Crehuet R, Lindorff-Larsen K. DEER-PREdict: Software for efficient calculation of spin-labeling EPR and NMR data from conformational ensembles. PLoS Comput Biol 2021; 17:e1008551. [PMID: 33481784 PMCID: PMC7857587 DOI: 10.1371/journal.pcbi.1008551] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 02/03/2021] [Accepted: 11/19/2020] [Indexed: 11/25/2022] Open
Abstract
Owing to their plasticity, intrinsically disordered and multidomain proteins require descriptions based on multiple conformations, thus calling for techniques and analysis tools that are capable of dealing with conformational ensembles rather than a single protein structure. Here, we introduce DEER-PREdict, a software program to predict Double Electron-Electron Resonance distance distributions as well as Paramagnetic Relaxation Enhancement rates from ensembles of protein conformations. DEER-PREdict uses an established rotamer library approach to describe the paramagnetic probes which are bound covalently to the protein.DEER-PREdict has been designed to operate efficiently on large conformational ensembles, such as those generated by molecular dynamics simulation, to facilitate the validation or refinement of molecular models as well as the interpretation of experimental data. The performance and accuracy of the software is demonstrated with experimentally characterized protein systems: HIV-1 protease, T4 Lysozyme and Acyl-CoA-binding protein. DEER-PREdict is open source (GPLv3) and available at github.com/KULL-Centre/DEERpredict and as a Python PyPI package pypi.org/project/DEERPREdict.
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Affiliation(s)
- Giulio Tesei
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - João M. Martins
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Micha B. A. Kunze
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Yong Wang
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Ramon Crehuet
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
- CSIC-Institute for Advanced Chemistry of Catalonia (IQAC), Barcelona, Spain
| | - Kresten Lindorff-Larsen
- Structural Biology and NMR Laboratory & the Linderstrøm-Lang Centre for Protein Science, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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2
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Mitra K, Ghanta P, Acharya S, Chakrapani G, Ramaiah B, Doble M. Dual inhibitors of SARS-CoV-2 proteases: pharmacophore and molecular dynamics based drug repositioning and phytochemical leads. J Biomol Struct Dyn 2020; 39:6324-6337. [PMID: 32698693 PMCID: PMC7441782 DOI: 10.1080/07391102.2020.1796802] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
SARS-related coronaviruses poses continual threat to humanity by rapidly mutating and emerging as severe pandemic outbreaks, including the current nCoV-19 pandemic. Hence a rapid drug repositioning and lead identification strategy are required to mitigate these outbreaks. We report a pharmacophore and molecular dynamics-based approach for drug repositioning and lead identification against dual targets (3CLp and PLp) of SARS-CoV-2. The pharmacophore model of 3CLp inhibitors was apolar with two aromatic and two H-bond acceptors, whereas that of PLp was relatively polar, bearing one aromatic and three H-bond acceptors. Pharmacophore-based virtual screening yielded six existing FDA-approved drugs and twelve natural products with both the pharmacophoric features. Among them are nelfinavir, tipranavir and licochalcone-D, which has shown better binding characteristics with both the proteases compared to lopinavir. The molecular dynamics revealed that the connecting loop (residues 176–199) of 3CLp is highly flexible, and hence, inhibitors should avoid high-affinity interactions with it. Lopinavir, due to its high affinity with the loop region, exhibited unstable binding. Further, the van der Waals size of the 3CLp inhibitors positively correlated with their binding affinity with 3CLp. However, the van der Waals size of a ligand should not cross a threshold of 572Å3, beyond which the ligands are likely to make high-affinity interaction with the loop and suffer unstable binding as observed in the case of lopinavir. Similarly, the total polar surface area of the ligands were found to be negatively correlated with their binding affinity with PLp.
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Affiliation(s)
- Kartik Mitra
- Department of Biotechnology, Bio-Engineering and Drug Design Lab, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology-Madras, Adayar, Chennai, Tamil Nadu, India
| | - Prasanth Ghanta
- Department of Biosciences, Sri Sathya Sai Institute of Higher Learning, Puttaparthi, Andhra Pradesh, India
| | - Sushank Acharya
- Department of Biotechnology, Bio-Engineering and Drug Design Lab, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology-Madras, Adayar, Chennai, Tamil Nadu, India
| | - Gayathri Chakrapani
- Department of Biotechnology, Bio-Engineering and Drug Design Lab, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology-Madras, Adayar, Chennai, Tamil Nadu, India
| | - Basavaraju Ramaiah
- Department of Biosciences, Sri Sathya Sai Institute of Higher Learning, Puttaparthi, Andhra Pradesh, India
| | - Mukesh Doble
- Department of Biotechnology, Bio-Engineering and Drug Design Lab, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology-Madras, Adayar, Chennai, Tamil Nadu, India
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3
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Raghuraman H, Chatterjee S, Das A. Site-Directed Fluorescence Approaches for Dynamic Structural Biology of Membrane Peptides and Proteins. Front Mol Biosci 2019; 6:96. [PMID: 31608290 PMCID: PMC6774292 DOI: 10.3389/fmolb.2019.00096] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Membrane proteins mediate a number of cellular functions and are associated with several diseases and also play a crucial role in pathogenicity. Due to their importance in cellular structure and function, they are important drug targets for ~60% of drugs available in the market. Despite the technological advancement and recent successful outcomes in determining the high-resolution structural snapshot of membrane proteins, the mechanistic details underlining the complex functionalities of membrane proteins is least understood. This is largely due to lack of structural dynamics information pertaining to different functional states of membrane proteins in a membrane environment. Fluorescence spectroscopy is a widely used technique in the analysis of functionally-relevant structure and dynamics of membrane protein. This review is focused on various site-directed fluorescence (SDFL) approaches and their applications to explore structural information, conformational changes, hydration dynamics, and lipid-protein interactions of important classes of membrane proteins that include the pore-forming peptides/proteins, ion channels/transporters and G-protein coupled receptors.
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Affiliation(s)
- H. Raghuraman
- Crystallography and Molecular Biology Division, Saha Institute of Nuclear Physics, Homi Bhabha National Institute, Kolkata, India
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4
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McGillewie L, Ramesh M, Soliman ME. Sequence, Structural Analysis and Metrics to Define the Unique Dynamic Features of the Flap Regions Among Aspartic Proteases. Protein J 2017; 36:385-396. [PMID: 28762197 DOI: 10.1007/s10930-017-9735-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Aspartic proteases are a class of hydrolytic enzymes that have been implicated in a number of diseases such as HIV, malaria, cancer and Alzheimer's. The flap region of aspartic proteases is a characteristic unique structural feature of these enzymes; and found to have a profound impact on protein overall structure, function and dynamics. Flap dynamics also plays a crucial role in drug binding and drug resistance. Therefore, understanding the structure and dynamic behavior of this flap regions is crucial in the design of potent and selective inhibitors against aspartic proteases. Defining metrics that can describe the flap motion/dynamics has been a challenging topic in literature. This review is the first attempt to compile comprehensive information on sequence, structure, motion and metrics used to assess the dynamics of the flap region of different aspartic proteases in "one pot". We believe that this review would be of critical importance to the researchers from different scientific domains.
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Affiliation(s)
- Lara McGillewie
- Molecular Modelling & Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal (UKZN), Westville, Durban, 4001, South Africa
| | - Muthusamy Ramesh
- Molecular Modelling & Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal (UKZN), Westville, Durban, 4001, South Africa
| | - Mahmoud E Soliman
- Molecular Modelling & Drug Design Research Group, School of Health Sciences, University of KwaZulu-Natal (UKZN), Westville, Durban, 4001, South Africa.
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5
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Meng XM, Hu WJ, Mu YG, Sheng XH. Effect of allosteric molecules on structure and drug affinity of HIV-1 protease by molecular dynamics simulations. J Mol Graph Model 2016; 70:153-162. [PMID: 27723563 DOI: 10.1016/j.jmgm.2016.09.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2016] [Revised: 09/24/2016] [Accepted: 09/27/2016] [Indexed: 11/16/2022]
Abstract
Recent experiments show that small molecules can bind onto the allosteric sites of HIV-1 protease (PR), which provides a starting point for developing allosteric inhibitors. However, the knowledge of the effect of such binding on the structural dynamics and binding free energy of the active site inhibitor and PR is still lacking. Here, we report 200ns long molecular dynamics simulation results to gain insight into the influences of two allosteric molecules (1H-indole-6-carboxylic acid, 1F1 and 2-methylcyclohexano, 4D9). The simulations demonstrate that both allosteric molecules change the PR conformation and stabilize the structures of PR and the inhibitor; the residues of the flaps are sensitive to the allosteric molecules and the flexibility of the residues is pronouncedly suppressed; the additions of the small molecules to the allosteric sites strengthen the binding affinities of 3TL-PR by about 12-15kal/mol in the binding free energy, which mainly arises from electrostatic term. Interestingly, it is found that the action mechanisms of 1F1 and 4D9 are different, the former behaviors like a doorman that keeps the inhibitor from escape and makes the flaps (door) partially open; the latter is like a wedge that expands the allosteric space and meanwhile closes the flaps. Our data provide a theoretical support for designing the allosteric inhibitor.
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Affiliation(s)
- Xian-Mei Meng
- School of Physics and Electronics, Shandong Normal University, Jinan 250014, China
| | - Wei-Jun Hu
- School of Physics and Electronics, Shandong Normal University, Jinan 250014, China.
| | - Yu-Guang Mu
- School of Biological Sciences, Nanyang Technological University, Singapore 639815, Singapore.
| | - Xie-Huang Sheng
- School of Chemistry, Shandong Normal University, Jinan 250014, China
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6
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Soares RO, Torres PHM, da Silva ML, Pascutti PG. Unraveling HIV protease flaps dynamics by Constant pH Molecular Dynamics simulations. J Struct Biol 2016; 195:216-226. [PMID: 27291071 DOI: 10.1016/j.jsb.2016.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Revised: 06/08/2016] [Accepted: 06/09/2016] [Indexed: 11/15/2022]
Abstract
The active site of HIV protease (HIV-PR) is covered by two flaps. These flaps are known to be essential for the catalytic activity of the HIV-PR, but their exact conformations at the different stages of the enzymatic pathway remain subject to debate. Understanding the correct functional dynamics of the flaps might aid the development of new HIV-PR inhibitors. It is known that, the HIV-PR catalytic efficiency is pH-dependent, likely due to the influence of processes such as charge transfer and protonation/deprotonation of ionizable residues. Several Molecular Dynamics (MD) simulations have reported information about the HIV-PR flaps. However, in MD simulations the protonation of a residue is fixed and thus it is not possible to study the correlation between conformation and protonation state. To address this shortcoming, this work attempts to capture, through Constant pH Molecular Dynamics (CpHMD), the conformations of the apo, substrate-bound and inhibitor-bound HIV-PR, which differ drastically in their flap arrangements. The results show that the HIV-PR flaps conformations are defined by the protonation of the catalytic residues Asp25/Asp25' and that these residues are sensitive to pH changes. This study suggests that the catalytic aspartates can modulate the opening of the active site and substrate binding.
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Affiliation(s)
- Rosemberg O Soares
- Instituto de Biofísica Carlos Chagas Filho (IBCCF), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil; Diretoria de Metrologia Aplicada às Ciências da Vida (DIMAV), Instituto Nacional de Metrologia Qualidade e Tecnologia (INMETRO), Xerém, Brazil.
| | - Pedro H M Torres
- Instituto de Biofísica Carlos Chagas Filho (IBCCF), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - Manuela L da Silva
- Diretoria de Metrologia Aplicada às Ciências da Vida (DIMAV), Instituto Nacional de Metrologia Qualidade e Tecnologia (INMETRO), Xerém, Brazil
| | - Pedro G Pascutti
- Instituto de Biofísica Carlos Chagas Filho (IBCCF), Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil; Diretoria de Metrologia Aplicada às Ciências da Vida (DIMAV), Instituto Nacional de Metrologia Qualidade e Tecnologia (INMETRO), Xerém, Brazil
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7
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Liu Z, Casey TM, Blackburn ME, Huang X, Pham L, de Vera IMS, Carter JD, Kear-Scott JL, Veloro AM, Galiano L, Fanucci GE. Pulsed EPR characterization of HIV-1 protease conformational sampling and inhibitor-induced population shifts. Phys Chem Chem Phys 2016; 18:5819-31. [PMID: 26489725 PMCID: PMC4758878 DOI: 10.1039/c5cp04556h] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The conformational landscape of HIV-1 protease (PR) can be experimentally characterized by pulsed-EPR double electron-electron resonance (DEER). For this characterization, nitroxide spin labels are attached to an engineered cysteine residue in the flap region of HIV-1 PR. DEER distance measurements from spin-labels contained within each flap of the homodimer provide a detailed description of the conformational sampling of apo-enzyme as well as induced conformational shifts as a function of inhibitor binding. The distance distribution profiles are further interpreted in terms of a conformational ensemble scheme that consists of four unique states termed "curled/tucked", "closed", "semi-open" and "wide-open" conformations. Reported here are the DEER results for a drug-resistant variant clinical isolate sequence, V6, in the presence of FDA approved protease inhibitors (PIs) as well as a non-hydrolyzable substrate mimic, CaP2. Results are interpreted in the context of the current understanding of the relationship between conformational sampling, drug resistance, and kinetic efficiency of HIV-1PR as derived from previous DEER and kinetic data for a series of HIV-1PR constructs that contain drug-pressure selected mutations or natural polymorphisms. Specifically, these collective results support the notion that inhibitor-induced closure of the flaps correlates with inhibitor efficiency and drug resistance. This body of work also suggests DEER as a tool for studying conformational sampling in flexible enzymes as it relates to function.
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Affiliation(s)
- Zhanglong Liu
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Thomas M Casey
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Mandy E Blackburn
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Xi Huang
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Linh Pham
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Ian Mitchelle S de Vera
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Jeffrey D Carter
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Jamie L Kear-Scott
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Angelo M Veloro
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Luis Galiano
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, PO BOX 117200, Gainesville, FL 32611-7200, USA.
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8
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Casey TM, Fanucci GE. Spin labeling and Double Electron-Electron Resonance (DEER) to Deconstruct Conformational Ensembles of HIV Protease. Methods Enzymol 2015; 564:153-87. [PMID: 26477251 DOI: 10.1016/bs.mie.2015.07.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
An understanding of macromolecular conformational equilibrium in biological systems is oftentimes essential to understand function, dysfunction, and disease. For the past few years, our lab has been utilizing site-directed spin labeling (SDSL), coupled with electron paramagnetic resonance (EPR) spectroscopy, to characterize the conformational ensemble and ligand-induced conformational shifts of HIV-1 protease (HIV-1PR). The biomedical importance of characterizing the fractional occupancy of states within the conformational ensemble critically impacts our hypothesis of a conformational selection mechanism of drug-resistance evolution in HIV-1PR. The purpose of the following chapter is to give a timeline perspective of our SDSL EPR approach to characterizing conformational sampling of HIV-1PR. We provide detailed instructions for the procedure utilized in analyzing distance profiles for HIV-1PR obtained from pulsed electron-electron double resonance (PELDOR). Specifically, we employ a version of PELDOR known as double electron-electron resonance (DEER). Data are processed with the software package "DeerAnalysis" (http://www.epr.ethz.ch/software), which implements Tikhonov regularization (TKR), to generate a distance profile from electron spin-echo amplitude modulations. We assign meaning to resultant distance profiles based upon a conformational sampling model, which is described herein. The TKR distance profiles are reconstructed with a linear combination of Gaussian functions, which is then statistically analyzed. In general, DEER has proven powerful for observing structural ensembles in proteins and, more recently, nucleic acids. Our goal is to present our advances in order to aid readers in similar applications.
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Affiliation(s)
- Thomas M Casey
- Department of Chemistry, University of Florida, Gainesville, Florida, USA
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, Gainesville, Florida, USA.
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9
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Potempa M, Nalivaika E, Ragland D, Lee SK, Schiffer CA, Swanstrom R. A Direct Interaction with RNA Dramatically Enhances the Catalytic Activity of the HIV-1 Protease In Vitro. J Mol Biol 2015; 427:2360-78. [PMID: 25986307 DOI: 10.1016/j.jmb.2015.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 05/08/2015] [Accepted: 05/08/2015] [Indexed: 01/09/2023]
Abstract
Though the steps of human immunodeficiency virus type 1 (HIV-1) virion maturation are well documented, the mechanisms regulating the proteolysis of the Gag and Gag-Pro-Pol polyproteins by the HIV-1 protease (PR) remain obscure. One proposed mechanism argues that the maturation intermediate p15NC must interact with RNA for efficient cleavage by the PR. We investigated this phenomenon and found that processing of multiple substrates by the HIV-1 PR was enhanced in the presence of RNA. The acceleration of proteolysis occurred independently from the substrate's ability to interact with nucleic acid, indicating that a direct interaction between substrate and RNA is not necessary for enhancement. Gel-shift assays demonstrated the HIV-1 PR is capable of interacting with nucleic acids, suggesting that RNA accelerates processing reactions by interacting with the PR rather than the substrate. All HIV-1 PRs examined have this ability; however, the HIV-2 PR does not interact with RNA and does not exhibit enhanced catalytic activity in the presence of RNA. No specific sequence or structure was required in the RNA for a productive interaction with the HIV-1 PR, which appears to be principally, though not exclusively, driven by electrostatic forces. For a peptide substrate, RNA increased the kinetic efficiency of the HIV-1 PR by an order of magnitude, affecting both turnover rate (k(cat)) and substrate affinity (K(m)). These results suggest that an allosteric binding site exists on the HIV-1 PR and that HIV-1 PR activity during maturation could be regulated in part by the juxtaposition of the enzyme with virion-packaged RNA.
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Affiliation(s)
- Marc Potempa
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Ellen Nalivaika
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Debra Ragland
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Sook-Kyung Lee
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Ronald Swanstrom
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Center for AIDS Research, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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10
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Carter JD, Gonzales EG, Huang X, Smith AN, de Vera IMS, D'Amore PW, Rocca JR, Goodenow MM, Dunn BM, Fanucci GE. Effects of PRE and POST therapy drug-pressure selected mutations on HIV-1 protease conformational sampling. FEBS Lett 2014; 588:3123-8. [PMID: 24983495 DOI: 10.1016/j.febslet.2014.06.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 06/16/2014] [Accepted: 06/16/2014] [Indexed: 01/11/2023]
Abstract
Conformational sampling of pre- and post-therapy subtype B HIV-1 protease sequences derived from a pediatric subject infected via maternal transmission with HIV-1 were characterized by double electron-electron resonance spectroscopy. The conformational ensemble of the PRE construct resembles native-like inhibitor bound states. In contrast, the POST construct, which contains accumulated drug-pressure selected mutations, has a predominantly semi-open conformational ensemble, with increased populations of open-like states. The single point mutant L63P, which is contained in PRE and POST, has decreased dynamics, particularly in the flap region, and also displays a closed-like conformation of inhibitor-bound states. These findings support our hypothesis that secondary mutations accumulate in HIV-1 protease to shift conformational sampling to stabilize open-like conformations, while maintaining the predominant semi-open conformation for activity.
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Affiliation(s)
- Jeffrey D Carter
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
| | - Estrella G Gonzales
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
| | - Xi Huang
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
| | - Adam N Smith
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
| | | | - Peter W D'Amore
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA
| | - James R Rocca
- Advanced Magnetic Resonance Imaging and Spectroscopy Facility, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Maureen M Goodenow
- Department of Pathology, Immunology and Laboratory Medicine, University of Florida College of Medicine, Gainesville, FL 32610-3633, USA
| | - Ben M Dunn
- Department of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, FL 32610-0245, USA
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA.
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11
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Huang X, Britto MD, Kear-Scott JL, Boone CD, Rocca JR, Simmerling C, Mckenna R, Bieri M, Gooley PR, Dunn BM, Fanucci GE. The role of select subtype polymorphisms on HIV-1 protease conformational sampling and dynamics. J Biol Chem 2014; 289:17203-14. [PMID: 24742668 DOI: 10.1074/jbc.m114.571836] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
HIV-1 protease is an essential enzyme for viral particle maturation and is a target in the fight against HIV-1 infection worldwide. Several natural polymorphisms are also associated with drug resistance. Here, we utilized both pulsed electron double resonance, also called double electron-electron resonance, and NMR (15)N relaxation measurements to characterize equilibrium conformational sampling and backbone dynamics of an HIV-1 protease construct containing four specific natural polymorphisms commonly found in subtypes A, F, and CRF_01 A/E. Results show enhanced backbone dynamics, particularly in the flap region, and the persistence of a novel conformational ensemble that we hypothesize is an alternative flap orientation of a curled open state or an asymmetric configuration when interacting with inhibitors.
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Affiliation(s)
- Xi Huang
- From the Department of Chemistry, University of Florida, Gainesville, Florida 32611
| | - Manuel D Britto
- From the Department of Chemistry, University of Florida, Gainesville, Florida 32611
| | - Jamie L Kear-Scott
- From the Department of Chemistry, University of Florida, Gainesville, Florida 32611
| | - Christopher D Boone
- the Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
| | - James R Rocca
- the Advanced Magnetic Resonance Imaging and Spectroscopy Facility, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610
| | - Carlos Simmerling
- the Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, and
| | - Robert Mckenna
- the Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
| | - Michael Bieri
- the Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Paul R Gooley
- the Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ben M Dunn
- the Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610
| | - Gail E Fanucci
- From the Department of Chemistry, University of Florida, Gainesville, Florida 32611,
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12
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Affiliation(s)
- Artur Gora
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Jan Brezovsky
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
| | - Jiri Damborsky
- Loschmidt Laboratories,
Department
of Experimental Biology and Research Centre for Toxic Compounds in
the Environment, Faculty of Science, Masaryk University, Kamenice 5/A13, 625 00 Brno, Czech Republic
- International Centre for Clinical
Research, St. Anne’s University Hospital Brno, Pekarska 53, 656 91 Brno, Czech Republic
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13
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de Vera IMS, Smith AN, Dancel MCA, Huang X, Dunn BM, Fanucci GE. Elucidating a relationship between conformational sampling and drug resistance in HIV-1 protease. Biochemistry 2013; 52:3278-88. [PMID: 23566104 DOI: 10.1021/bi400109d] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Enzyme targets in rapidly replicating systems, such as retroviruses, commonly respond to drug-selective pressure with mutations arising in the active site pocket that limit inhibitor effectiveness by introducing steric hindrance or by eliminating essential molecular interactions. However, these primary mutations are disposed to compromising pathogenic fitness. Emerging secondary mutations, which are often found outside of the binding cavity, may or can restore fitness while maintaining drug resistance. The accumulated drug pressure selected mutations could have an indirect effect in the development of resistance, such as altering protein flexibility or the dynamics of protein-ligand interactions. Here, we show that accumulation of mutations in a drug-resistant HIV-1 protease (HIV-1 PR) variant, D30N/M36I/A71V, changes the fractional occupancy of the equilibrium conformational sampling ensemble. Correlations are made among populations of the conformational states, namely, closed-like, semiopen, and open-like, with inhibition constants, as well as kinetic parameters. Mutations that stabilize a closed-like conformation correlate with enzymes of lowered activity and with higher affinity for inhibitors, which is corroborated by a further increase in the fractional occupancy of the closed state upon addition of inhibitor or substrate-mimic. Cross-resistance is found to correlate with combinations of mutations that increase the population of the open-like conformations at the expense of the closed-like state while retaining native-like occupancy of the semiopen population. These correlations suggest that at least three states are required in the conformational sampling model to establish the emergence of drug resistance in HIV-1 PR. More importantly, these results shed light on a possible mechanism whereby mutations combine to impart drug resistance while maintaining catalytic activity.
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Affiliation(s)
- Ian Mitchelle S de Vera
- Department of Chemistry, P.O. Box 117200, University of Florida , Gainesville, Florida 32611-7200, United States
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14
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Tiefenbrunn T, Forli S, Baksh MM, Chang MW, Happer M, Lin YC, Perryman AL, Rhee JK, Torbett BE, Olson AJ, Elder JH, Finn MG, Stout CD. Small molecule regulation of protein conformation by binding in the Flap of HIV protease. ACS Chem Biol 2013; 8:1223-31. [PMID: 23540839 DOI: 10.1021/cb300611p] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fragment indole-6-carboxylic acid (1F1), previously identified as a flap site binder in a fragment-based screen against HIV protease (PR), has been cocrystallized with pepstatin-inhibited PR and with apo-PR. Another fragment, 3-indolepropionic acid (1F1-N), predicted by AutoDock calculations and confirmed in a novel inhibition of nucleation crystallization assay, exploits the same interactions in the flap site in two crystal structures. Both 1F1 and 1F1-N bind to the closed form of apo-PR and to pepstatin:PR. In solution, 1F1 and 1F1-N raise the Tm of apo-PR by 3.5-5 °C as assayed by differential scanning fluorimetry (DSF) and show equivalent low-micromolar binding constants to both apo-PR and pepstatin:PR, assayed by backscattering interferometry (BSI). The observed signal intensities in BSI are greater for each fragment upon binding to apo-PR than to pepstatin-bound PR, consistent with greater conformational change in the former binding event. Together, these data indicate that fragment binding in the flap site favors a closed conformation of HIV PR.
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Affiliation(s)
- Theresa Tiefenbrunn
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Stefano Forli
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Michael M. Baksh
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Max W. Chang
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Meaghan Happer
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Ying-Chuan Lin
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Alexander L. Perryman
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Jin-Kyu Rhee
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Bruce E. Torbett
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - Arthur J. Olson
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - John H. Elder
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - M. G. Finn
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
| | - C. David Stout
- Deparatment
of Integrative Structural and Computational Biology, ‡Department of Chemistry, §Department of Molecular
and Experimental Medicine, ∥Department of Immunology and Microbial Science, The Scripps Research Institute, 10550
N. Torrey Pines Rd., La Jolla, California 92037, United States
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15
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How conformational changes can affect catalysis, inhibition and drug resistance of enzymes with induced-fit binding mechanism such as the HIV-1 protease. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2013; 1834:867-73. [PMID: 23376188 DOI: 10.1016/j.bbapap.2013.01.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Revised: 01/21/2013] [Accepted: 01/24/2013] [Indexed: 11/21/2022]
Abstract
A central question is how the conformational changes of proteins affect their function and the inhibition of this function by drug molecules. Many enzymes change from an open to a closed conformation upon binding of substrate or inhibitor molecules. These conformational changes have been suggested to follow an induced-fit mechanism in which the molecules first bind in the open conformation in those cases where binding in the closed conformation appears to be sterically obstructed such as for the HIV-1 protease. In this article, we present a general model for the catalysis and inhibition of enzymes with induced-fit binding mechanism. We derive general expressions that specify how the overall catalytic rate of the enzymes depends on the rates for binding, for the conformational changes, and for the chemical reaction. Based on these expressions, we analyze the effect of mutations that mainly shift the conformational equilibrium on catalysis and inhibition. If the overall catalytic rate is limited by product unbinding, we find that mutations that destabilize the closed conformation relative to the open conformation increase the catalytic rate in the presence of inhibitors by a factor exp(ΔΔGC/RT) where ΔΔGC is the mutation-induced shift of the free-energy difference between the conformations. This increase in the catalytic rate due to changes in the conformational equilibrium is independent of the inhibitor molecule and, thus, may help to understand how non-active-site mutations can contribute to the multi-drug-resistance that has been observed for the HIV-1 protease. A comparison to experimental data for the non-active-site mutation L90M of the HIV-1 protease indicates that the mutation slightly destabilizes the closed conformation of the enzyme. 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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16
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Huang X, de Vera IMS, Veloro AM, Blackburn ME, Kear JL, Carter JD, Rocca JR, Simmerling C, Dunn BM, Fanucci GE. Inhibitor-induced conformational shifts and ligand-exchange dynamics for HIV-1 protease measured by pulsed EPR and NMR spectroscopy. J Phys Chem B 2012; 116:14235-44. [PMID: 23167829 PMCID: PMC3709468 DOI: 10.1021/jp308207h] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Double electron-electron resonance (DEER) spectroscopy was utilized to investigate shifts in conformational sampling induced by nine FDA-approved protease inhibitors (PIs) and a nonhydrolyzable substrate mimic for human immunodeficiency virus type 1 protease (HIV-1 PR) subtype B, subtype C, and CRF_01 A/E. The ligand-bound subtype C protease has broader DEER distance profiles, but trends for inhibitor-induced conformational shifts are comparable to those previously reported for subtype B. Ritonavir, one of the strong-binding inhibitors for subtypes B and C, induces less of the closed conformation in CRF_01 A/E. (1)H-(15)N heteronuclear single-quantum coherence (HSQC) spectra were acquired for each protease construct titrated with the same set of inhibitors. NMR (1)H-(15)N HSQC titration data show that inhibitor residence time in the protein binding pocket, inferred from resonance exchange broadening, shifting or splitting correlates with the degree of ligand-induced flap closure measured by DEER spectroscopy. These parallel results show that the ligand-induced conformational shifts resulting from protein-ligand interactions characterized by DEER spectroscopy of HIV-1 PR obtained at the cryogenic temperature are consistent with more physiological solution protein-ligand interactions observed by solution NMR spectroscopy.
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Affiliation(s)
- Xi Huang
- Department of Chemistry, University of Florida, PO Box 117200, Gainesville, Florida 32611, USA
| | | | - Angelo M. Veloro
- Department of Chemistry, University of Florida, PO Box 117200, Gainesville, Florida 32611, USA
| | - Mandy E. Blackburn
- Department of Chemistry, University of Florida, PO Box 117200, Gainesville, Florida 32611, USA
| | - Jamie L. Kear
- Department of Chemistry, University of Florida, PO Box 117200, Gainesville, Florida 32611, USA
| | - Jeffery D. Carter
- Department of Chemistry, University of Florida, PO Box 117200, Gainesville, Florida 32611, USA
| | - James R. Rocca
- Advanced Magnetic Resonance Imaging and Spectroscopy Facility, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610, USA
| | - Carlos Simmerling
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794, USA
| | - Ben M. Dunn
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida 32610, USA
| | - Gail E. Fanucci
- Department of Chemistry, University of Florida, PO Box 117200, Gainesville, Florida 32611, USA
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17
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de Vera IMS, Blackburn ME, Fanucci GE. Correlating conformational shift induction with altered inhibitor potency in a multidrug resistant HIV-1 protease variant. Biochemistry 2012; 51:7813-5. [PMID: 23009326 DOI: 10.1021/bi301010z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Inhibitor-induced conformational ensemble shifts in a multidrug resistant HIV-1 protease variant, MDR769, are characterized by site-directed spin labeling double electron-electron resonance spectroscopy. For MDR769 compared to the native enzyme, changes in inhibitor IC(50) values are related to a parameter defined as |ΔC|, which is the relative change in the inhibitor-induced shift to the closed state. Specifically, a linear correlation is found between |ΔC| and the magnitude of the change in IC(50), provided that inhibitor binding is not too weak. Moreover, inhibitors that exhibit MDR769 resistance no longer induce a strong shift to a closed conformational ensemble as seen previously in the native enzyme.
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Affiliation(s)
- Ian Mitchelle S de Vera
- Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, Florida 32611, USA
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18
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Limiting assumptions in structure-based design: binding entropy. J Comput Aided Mol Des 2012; 26:3-8. [PMID: 22212342 DOI: 10.1007/s10822-011-9494-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 11/09/2011] [Indexed: 01/08/2023]
Abstract
In order to deal with the complexity of biological systems at the atomic level, limiting assumptions are often made which do not reflect the reality of the system under study. One example is the assumption that the entropy of binding of the macromolecule is not influenced significantly by the different ligands. Recent experimental data on ligands binding to HIV-1 protease challenge this assumption.
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19
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Protein conformational dynamics in the mechanism of HIV-1 protease catalysis. Proc Natl Acad Sci U S A 2011; 108:20982-7. [PMID: 22158985 DOI: 10.1073/pnas.1111202108] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have used chemical protein synthesis and advanced physical methods to probe dynamics-function correlations for the HIV-1 protease, an enzyme that has received considerable attention as a target for the treatment of AIDS. Chemical synthesis was used to prepare a series of unique analogues of the HIV-1 protease in which the flexibility of the "flap" structures (residues 37-61 in each monomer of the homodimeric protein molecule) was systematically varied. These analogue enzymes were further studied by X-ray crystallography, NMR relaxation, and pulse-EPR methods, in conjunction with molecular dynamics simulations. We show that conformational isomerization in the flaps is correlated with structural reorganization of residues in the active site, and that it is preorganization of the active site that is a rate-limiting factor in catalysis.
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20
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Karthik S, Senapati S. Dynamic flaps in HIV-1 protease adopt unique ordering at different stages in the catalytic cycle. Proteins 2011; 79:1830-40. [PMID: 21465560 DOI: 10.1002/prot.23008] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 01/13/2011] [Accepted: 01/17/2011] [Indexed: 11/07/2022]
Abstract
The flexibility of HIV-1 protease flaps is known to be essential for the enzymatic activity. Here we attempt to capture a multitude of conformations of the free and substrate-bound HIV-1 protease that differ drastically in their flap arrangements. The substrate binding process suggests the opening of active site gate in conjunction with a reversal of flap tip ordering, from the native semiopen state. The reversed-flap, open-gated enzyme readily transforms to a closed conformation after proper placement of the substrate into the binding cleft. After substrate processing, the closed state protease which possessed opposite flap ordering relative to the semiopen state, encounters another flap reversal via a second open conformation that facilitates the evolution of native semiopen state of correct flap ordering. The complicated transitional pathway, comprising of many high and low energy states, is explored by combining standard and activated molecular dynamics (MD) simulation techniques. The study not only complements the existing findings from X-ray, NMR, EPR, and MD studies but also provides a wealth of detailed information that could help the structure-based drug design process.
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Affiliation(s)
- Suresh Karthik
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600036, India
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21
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Wang C, Guo Q, Fu Y. Theoretical Analysis of the Detailed Mechanism of Native Chemical Ligation Reactions. Chem Asian J 2011; 6:1241-51. [DOI: 10.1002/asia.201000760] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Indexed: 12/22/2022]
Affiliation(s)
- Chen Wang
- Department of Chemistry, University of Science and Technology of China, Hefei 230026 (China), Fax: (+86) 551‐3606689
| | - Qing‐Xiang Guo
- Department of Chemistry, University of Science and Technology of China, Hefei 230026 (China), Fax: (+86) 551‐3606689
| | - Yao Fu
- Department of Chemistry, University of Science and Technology of China, Hefei 230026 (China), Fax: (+86) 551‐3606689
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22
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Adkar BV, Jana B, Bagchi B. Role of water in the enzymatic catalysis: study of ATP + AMP → 2ADP conversion by adenylate kinase. J Phys Chem A 2010; 115:3691-7. [PMID: 20836529 DOI: 10.1021/jp104787s] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The catalytic conversion ATP + AMP → 2ADP by the enzyme adenylate kinase (ADK) involves the binding of one ATP molecule to the LID domain and one AMP molecule to the NMP domain. The latter is followed by a phosphate transfer and then the release of two ADP molecules. We have computed a novel two-dimensional configurational free energy surface (2DCFES), with one reaction coordinate each for the LID and the NMP domain motions, while considering explicit water interactions. Our computed 2DCFES clearly reveals the existence of a stable half-open half-closed (HOHC) intermediate state of the enzyme. Cycling of the enzyme through the HOHC state reduces the conformational free energy barrier for the reaction by about 20 kJ/mol. We find that the stability of the HOHC state (missed in all earlier studies with implicit solvent model) is largely because of the increase of specific interactions of the polar amino acid side chains with water, particularly with the arginine and the histidine residues. Free energy surface of the LID domain is rather rugged, which can conveniently slow down LID's conformational motion, thus facilitating a new substrate capture after the product release in the catalytic cycle.
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Affiliation(s)
- Bharat V Adkar
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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23
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Perryman AL, Zhang Q, Soutter HH, Rosenfeld R, McRee DE, Olson AJ, Elder JE, Stout CD. Fragment-based screen against HIV protease. Chem Biol Drug Des 2010; 75:257-68. [PMID: 20659109 DOI: 10.1111/j.1747-0285.2009.00943.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have employed a fragment-based screen against wild-type (NL4-3) HIV protease (PR) using the Active Sight fragment library and X-ray crystallography. The experiments reveal two new binding sites for small molecules. PR was co-crystallized with fragments, or crystals were soaked in fragment solutions, using five crystal forms, and 378 data sets were collected to 2.3-1.3 A resolution. Fragment binding induces a distinct conformation and specific crystal form of TL-3 inhibited PR during co-crystallization. One fragment, 2-methylcyclohexanol, binds in the 'exo site' adjacent to the Gly(16)Gly(17)Gln(18)loop where the amide of Gly(17)is a specific hydrogen bond donor, and hydrophobic contacts occur with the side chains of Lys(14)and Leu(63). Another fragment, indole-6-carboxylic acid, binds on the 'outside/top of the flap' via hydrophobic contacts with Trp(42), Pro(44), Met(46), and Lys(55), a hydrogen bond with Val(56), and a salt-bridge with Arg(57). 2-acetyl-benzothiophene also binds at this site. This study is the first fragment-based crystallographic screen against HIV PR, and the first time that fragments were screened against an inhibitor-bound drug target to search for compounds that both bind to novel sites and stabilize the inhibited conformation of the target.
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Affiliation(s)
- Alexander L Perryman
- Department of Molecular Biology, The Scripps Research Institute, 10550 N. Torrey Pines Rd., La Jolla, CA 92037, USA
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24
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Kear JL, Blackburn ME, Veloro AM, Dunn BM, Fanucci GE. Subtype polymorphisms among HIV-1 protease variants confer altered flap conformations and flexibility. J Am Chem Soc 2010; 131:14650-1. [PMID: 19788299 DOI: 10.1021/ja907088a] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) protease plays a fundamental role in the maturation and life cycle of the retrovirus HIV-1, as it functions in regulating post-translational processing of the viral polyproteins gag and gag-pol; thus, it is a key target of AIDS antiviral therapy. Accessibility of substrate to the active site is mediated by two flaps, which must undergo a large conformational change from an open to a closed conformation during substrate binding and catalysis. The electron paramagnetic resonance (EPR) method of site-directed spin labeling (SDSL) with double electron-electron resonance (DEER) spectroscopy was utilized to monitor the conformations of the flaps in apo HIV-1 protease (HIV-1PR), subtypes B, C, and F, CRF01_A/E, and patient isolates V6 and MDR 769. The distance distribution profiles obtained from analysis of the dipolar modulated echo curves were reconstructed to yield a set of Gaussian-shaped populations, which provide an analysis of the flap conformations sampled. The relative percentages of each conformer population described as "tucked/curled", "closed", "semi-open", and "wide-open" were determined and compared for various constructs. The results and analyses show that sequence variations among subtypes, CRFs, and patient isolates of apo HIV-1PR alter the average flap conformation in a way that can be understood as inducing shifts in the relative populations, or conformational sampling, of the previously described four conformations for HIV-1PR.
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Affiliation(s)
- Jamie L Kear
- Department of Chemistry, P.O. Box 117200, University of Florida, Gainesville, Florida 32611-7200, USA
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25
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Qin S, Minh DL, McCammon JA, Zhou HX. Method to Predict Crowding Effects by Postprocessing Molecular Dynamics Trajectories: Application to the Flap Dynamics of HIV-1 Protease. J Phys Chem Lett 2010; 1:107-110. [PMID: 20228897 PMCID: PMC2837415 DOI: 10.1021/jz900023w] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Accepted: 11/03/2009] [Indexed: 05/06/2023]
Abstract
The internal dynamics of proteins inside of cells may be affected by the crowded intracellular environments. Here, we test a novel approach to simulations of crowding, in which simulations in the absence of crowders are postprocessed to predict crowding effects, against the direct approach of simulations in the presence of crowders. The effects of crowding on the flap dynamics of HIV-1 protease predicted by the postprocessing approach are found to agree well with those calculated by the direct approach. The postprocessing approach presents distinct advantages over the direct approach in terms of accuracy and speed and is expected to have broad impact on atomistic simulations of macromolecular crowding.
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Affiliation(s)
- Sanbo Qin
- Department of Physics and Institute
of Molecular Biophysics, Florida State University, Tallahassee, Florida
32306
| | - David
D. L. Minh
- Departments of Chemistry and
Biochemistry and of Pharmacology, Center for Theoretical Biological
Physics, and Howard Hughes Medical Institute, University of California
at San Diego, La Jolla, California 92093-0365
| | - J. Andrew McCammon
- Departments of Chemistry and
Biochemistry and of Pharmacology, Center for Theoretical Biological
Physics, and Howard Hughes Medical Institute, University of California
at San Diego, La Jolla, California 92093-0365
| | - Huan-Xiang Zhou
- Department of Physics and Institute
of Molecular Biophysics, Florida State University, Tallahassee, Florida
32306
- To whom correspondence should be
addressed. Phone: (850) 645-1336. Fax: (850) 644-7244. E-mail:
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26
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Abstract
Soon after its discovery, the attempts to develop anti-AIDS therapeutics focused on the retroviral protease (PR)-an enzyme used by lentiviruses to process the precursor polypeptide into mature viral proteins. An urgent need for the three-dimensional structure of PR to guide rational drug design prompted efforts to produce milligram quantities of this enzyme. However, only minute amounts of PR were present in the HIV-1 and HIV-2 viruses, and initial attempts to express this protein in bacteria were not successful. This review describes X-ray crystallographic studies of the retroviral proteases carried out at NCI-Frederick in the late 1980s and early 1990s and puts into perspective the crucial role that the total protein chemical synthesis played in unraveling the structure, mechanism of action, and inhibition of HIV-1 PR. Notably, the first fully correct structure of HIV-1 PR and the first cocrystal structure of its complex with an inhibitor (a substrate-derived, reduced isostere hexapeptide MVT-101) were determined using chemically synthesized protein. Most importantly, these sets of coordinates were made freely available to the research community and were used worldwide to solve X-ray structures of HIV-1 PR complexes with an array of inhibitors and set in motion a variety of theoretical studies. Publication of the structure of chemically synthesized HIV-1 PR complexed with MVT-101 preceded only by six years the approval of the first PR inhibitor as an anti-AIDS drug.
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Affiliation(s)
- Maria Miller
- Protein Structure Section, Macromolecular Crystallography Laboratory, NCI-Frederick, Frederick, MD 21702-1201, USA.
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27
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Blackburn ME, Veloro AM, Fanucci GE. Monitoring inhibitor-induced conformational population shifts in HIV-1 protease by pulsed EPR spectroscopy. Biochemistry 2009; 48:8765-7. [PMID: 19691291 DOI: 10.1021/bi901201q] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Double electron-electron resonance (DEER), a pulsed electron paramagnetic resonance (EPR) spectroscopy technique, was utilized to characterize conformational population shifts in HIV-1 protease (HIV-1PR) upon interaction with various inhibitors. Distances between spin-labeled sites in the flap region of HIV-1PR were determined, and detailed analyses provide population percentages for the ensemble flap conformations upon interaction with inhibitor or substrate. Comparisons are made between the percentage of the closed conformer seen with DEER and enzymatic inhibition constants, thermodynamic dissociation constants, and the number of hydrogen bonds identified in crystallographic complexes.
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Affiliation(s)
- Mandy E Blackburn
- Department of Chemistry, P.O. Box 117200, University of Florida, Gainesville, Florida 32611-7200, USA
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28
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Xin Y, Gadda G, Hamelberg D. The Cluster of Hydrophobic Residues Controls the Entrance to the Active Site of Choline Oxidase. Biochemistry 2009; 48:9599-605. [DOI: 10.1021/bi901295a] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | - Giovanni Gadda
- Department of Chemistry
- Department of Biology
- The Center for Biotechnology and Drug Design
| | - Donald Hamelberg
- Department of Chemistry
- The Center for Biotechnology and Drug Design
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