1
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Novak J, Pathak P, Grishina MA, Potemkin VA. The design of compounds with desirable properties - The anti-HIV case study. J Comput Chem 2023; 44:1016-1030. [PMID: 36533526 DOI: 10.1002/jcc.27061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 11/14/2022] [Accepted: 12/04/2022] [Indexed: 12/23/2022]
Abstract
Efficacy and safety are among the most desirable characteristics of an ideal drug. The tremendous increase in computing power and the entry of artificial intelligence into the field of computational drug design are accelerating the process of identifying, developing, and optimizing potential drugs. Here, we present novel approach to design new molecules with desired properties. We combined various neural networks and linear regression algorithms to build models for cytotoxicity and anti-HIV activity based on Continual Molecular Interior analysis (CoMIn) and Cinderella's Shoe (CiS) derived molecular descriptors. After validating the reliability of the models, a genetic algorithm was coupled with the Des-Pot Grid algorithm to generate new molecules from a predefined pool of molecular fragments and predict their bioactivity and cytotoxicity. This combination led to the proposal of 16 hit molecules with high anti-HIV activity and low cytotoxicity. The anti-SARS-CoV-2 activity of the hits was predicted.
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Affiliation(s)
- Jurica Novak
- Department of Biotechnology, University of Rijeka, Rijeka, Croatia
- Center for Artificial Intelligence and Cybersecurity, University of Rijeka, Rijeka, Croatia
- Scientific and Educational Center "Biomedical Technologies", Higher Medical & Biological School, South Ural State University, Chelyabinsk, Russia
| | - Prateek Pathak
- Laboratory of Computational Modelling of Drugs, Higher Medical & Biological School, South Ural State University, Chelyabinsk, Russia
| | - Maria A Grishina
- Laboratory of Computational Modelling of Drugs, Higher Medical & Biological School, South Ural State University, Chelyabinsk, Russia
| | - Vladimir A Potemkin
- Laboratory of Computational Modelling of Drugs, Higher Medical & Biological School, South Ural State University, Chelyabinsk, Russia
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2
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Sherry D, Worth R, Sayed Y. Elasticity-Associated Functionality and Inhibition of the HIV Protease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1371:79-108. [PMID: 34351572 DOI: 10.1007/5584_2021_655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
HIV protease plays a critical role in the life cycle of the virus through the generation of mature and infectious virions. Detailed knowledge of the structure of the enzyme and its substrate has led to the development of protease inhibitors. However, the development of resistance to all currently available protease inhibitors has contributed greatly to the decreased success of antiretroviral therapy. When therapy failure occurs, multiple mutations are found within the protease sequence starting with primary mutations, which directly impact inhibitor binding, which can also negatively impact viral fitness and replicative capacity by decreasing the binding affinity of the natural substrates to the protease. As such, secondary mutations which are located outside of the active site region accumulate to compensate for the recurrently deleterious effects of primary mutations. However, the resistance mechanism of these secondary mutations is not well understood, but what is known is that these secondary mutations contribute to resistance in one of two ways, either through increasing the energetic penalty associated with bringing the protease into the closed conformation, or, through decreasing the stability of the protein/drug complex in a manner that increases the dissociation rate of the drug, leading to diminished inhibition. As a result, the elasticity of the enzyme-substrate complex has been implicated in the successful recognition and catalysis of the substrates which may be inferred to suggest that the elasticity of the enzyme/drug complex plays a role in resistance. A realistic representation of the dynamic nature of the protease may provide a more powerful tool in structure-based drug design algorithms.
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Affiliation(s)
- Dean Sherry
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
| | - Roland Worth
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa
| | - Yasien Sayed
- Protein Structure-Function Research Unit, School of Molecular and Cell Biology, University of the Witwatersrand, Johannesburg, South Africa.
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3
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Chatzigoulas A, Cournia Z. Rational design of allosteric modulators: Challenges and successes. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2021. [DOI: 10.1002/wcms.1529] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Alexios Chatzigoulas
- Biomedical Research Foundation Academy of Athens Athens Greece
- Department of Informatics and Telecommunications National and Kapodistrian University of Athens Athens Greece
| | - Zoe Cournia
- Biomedical Research Foundation Academy of Athens Athens Greece
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4
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Mavian C, Coman RM, Zhang X, Pomeroy S, Ostrov DA, Dunn BM, Sleasman JW, Goodenow MM. Molecular Docking-Based Screening for Novel Inhibitors of the Human Immunodeficiency Virus Type 1 Protease that Effectively Reduce the Viral Replication in Human Cells. JOURNAL OF AIDS & CLINICAL RESEARCH 2021; 12:841. [PMID: 34950525 PMCID: PMC8694022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Therapeutic pressure by protease inhibitors (PIs) contributes to accumulation of mutations in the HIV type 1 (HIV-1) protease (PR) leading to development of drug resistance with subsequent therapy failure. Current PIs target the active site of PR in a competitive manner. Identification of molecules that exploit non-active site mechanisms of inhibition is essential to overcome resistance to current PIs. Potential non-active site HIV-1 protease (PR) inhibitors (PI) were identified by in silico screening of almost 140,000 molecules targeting the hinge region of PR. Inhibitory activity of best docking compounds was tested in an in vitro PR inhibition biochemical assay. Five compounds inhibited PR from multiple HIV-1 sub-types in vitro and reduced replicative capacity by PI-sensitive or multi-PI resistant HIV-1 variants in human cells ex vivo. Antiviral activity was boosted when combined with Ritonavir, potentially diminishing development of drug resistance, while providing effective treatment for drug resistant HIV-1 variants.
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Affiliation(s)
- Carla Mavian
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Roxana M Coman
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA,Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Xinrui Zhang
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Steve Pomeroy
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - David A. Ostrov
- Department of Pathology, Immunology and Laboratory Medicine, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Ben M Dunn
- Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - John W. Sleasman
- Pediatric Allergy, Immunology, and Pulmonary Medicine, Duke University, Durham, NC 27710, USA
| | - Maureen M Goodenow
- Office of AIDS Research, National Institutes of Health, USA,Address for Correspondence: Maureen M Goodenow, Office of AIDS Research, National Institutes of Health, USA, Tel: + 3522132304;
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5
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Novel radial distribution function approach in the study of point mutations: the HIV-1 protease case study. Future Med Chem 2020; 12:1025-1036. [PMID: 32319305 DOI: 10.4155/fmc-2020-0042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background: Mutations are one of the engines of evolution. Under constant stress pressure, mutations can lead to the emergence of unwanted, drug-resistant entities. Methodology: The radial distribution function weighted by the number of valence shell electrons is used to design quantitative structure-activity relationship (QSAR) model relating descriptors with the inhibition constant for a series of wild-type HIV-1 protease inhibitor complexes. The residuals of complexes with mutant HIV-1 protease were correlated with the energy of the highest occupied molecular orbitals of the residues introduced to enzyme via point mutations. Conclusion: Successful identification of residues Ile3, Asp25, Val32 and Ile50 as the one whose substitution influences the inhibition constant the most, demonstrates the potential of the proposed methodology for the study of the effects of point mutations.
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6
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Characterization of HIV-2 Protease Structure by Studying Its Asymmetry at the Different Levels of Protein Description. Symmetry (Basel) 2018. [DOI: 10.3390/sym10110644] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
HIV-2 protease (PR2) is a homodimer, which is an important target in the treatment of the HIV-2 infection. In this study, we developed an in silico protocol to analyze and characterize the asymmetry of the unbound PR2 structure using three levels of protein description by comparing the conformation, accessibility, and flexibility of each residue in the two PR2 chains. Our results showed that 65% of PR2 residues have at least one of the three studied asymmetries (structural, accessibility, or flexibility) with 10 positions presenting the three asymmetries in the same time. In addition, we noted that structural and flexibility asymmetries are linked indicating that the structural asymmetry of some positions result from their large flexibility. By comparing the structural asymmetry of the crystallographic and energetically minimized structures of the unbound PR2, we confirmed that the structural asymmetry of unbound PR2 is an intrinsic property of this protein with an important role for the PR2 deformation upon ligand binding. This analysis also allowed locating asymmetries corresponding to crystallization artefacts. This study provides insight that will help to better understand the structural deformations of PR2 and to identify key positions for ligand binding.
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7
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Chen J, Peng C, Wang J, Zhu W. Exploring molecular mechanism of allosteric inhibitor to relieve drug resistance of multiple mutations in HIV-1 protease by enhanced conformational sampling. Proteins 2018; 86:1294-1305. [PMID: 30260044 DOI: 10.1002/prot.25610] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/02/2018] [Accepted: 09/23/2018] [Indexed: 12/12/2022]
Abstract
Recently, allosteric regulations of HIV-1 protease (PR) are suggested as a promising approach to relieve drug resistance of mutations toward inhibitors targeting the active site of PR. Replica-exchange molecular dynamics (REMD) simulations and normal mode analysis (NMA) are integrated to enhance conformational sampling of PR. Molecular mechanics generalized Born surface area (MM-GBSA) method was applied to calculate binding free energies of three inhibitors APV, DRV, and NIT to the wild-type (WT) and multidrug resistance (MDR) PRs. The results suggest that binding free energies of APV and DRV are decreased in the MDR PR relative to the WT PR, suggesting drug resistance of mutations on these two inhibitors. However, the binding ability of the allosteric inhibitor NIT is not impaired in the MDR PR. In addition, internal dynamics analysis based on REMD simulations proves that mutations hardly produce obvious effect on the conformation of the MDR PR in comparison to the WT PR. Scanning of hydrophobic contacts and hydrogen bond contacts of inhibitors with residues of PRs on the concatenated trajectories of REMD demonstrates that mutations change the symmetric interaction networks of APV and DRV with PR, but do not generate obvious influence on the asymmetric interaction network of NIT with PR. In summary, allosteric inhibitor NIT can adapt the MDR PR better than those inhibitors toward the active site of PR, thus allosteric inhibitors of PR may be a possible channel to overcome drug resistance of PR.
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Affiliation(s)
- Jianzhong Chen
- School of Science, Shandong Jiaotong University, Jinan, China.,Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Cheng Peng
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.,School of Chemistry, University of Chinese Academy of Sciences, Beijing, China
| | - Jinan Wang
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Weiliang Zhu
- Drug Discovery and Design Center, CAS Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
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8
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Evolution of inhibitor-resistant natural mutant forms of HIV-1 protease probed by pre-steady state kinetic analysis. Biochimie 2017; 142:125-134. [PMID: 28843613 DOI: 10.1016/j.biochi.2017.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 08/21/2017] [Indexed: 11/23/2022]
Abstract
Pre-steady state kinetic analysis of mechanistic features of substrate binding and processing is crucial for insight into the evolution of inhibitor-resistant forms of HIV-1 protease. These data may provide a correct vector for rational drug design assuming possible intrinsic dynamic effects. These data should also give some clues to the molecular mechanism of protease action and resistance to inhibitors. Here we report pre-steady state kinetics of the interaction of wild type or mutant forms of HIV-1 protease with a FRET-labeled peptide. The three-stage "minimal" kinetic scheme with first and second reversible steps of substrate binding and with following irreversible peptide cleavage step adequately described experimental data. For the first time, a set of "elementary" kinetic parameters of wild type HIV-1 protease and its natural mutant inhibitor-resistant forms MDR-HM, ANAM-11 and prDRV4 were compared. Inhibitors of the first and second generation were used to estimate the inhibitory effects on HIV-1 protease activity. The resulting set of kinetic data supported that the mutant forms are kinetically unaffected by inhibitors of the first generation, proving their functional resistance to these compounds. The second generation inhibitor darunavir inhibited mutant forms MDR-HM and ANAM-11, but was ineffective against prDRV4. Our kinetic data revealed that these inhibitors induced different conformational changes in the enzyme and, thereby they have different mode of binding in the enzyme active site. These data confirmed hypothesis that the driving force of the inhibitor-resistance evolution is disruption of enzyme-inhibitor complex by changing of the contact network in the inhibitor binding site.
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9
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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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10
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Ghanakota P, Carlson HA. Driving Structure-Based Drug Discovery through Cosolvent Molecular Dynamics. J Med Chem 2016; 59:10383-10399. [PMID: 27486927 DOI: 10.1021/acs.jmedchem.6b00399] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Identifying binding hotspots on protein surfaces is of prime interest in structure-based drug discovery, either to assess the tractability of pursuing a protein target or to drive improved potency of lead compounds. Computational approaches to detect such regions have traditionally relied on energy minimization of probe molecules onto static protein conformations in the absence of the natural aqueous environment. Advances in high performance computing now allow us to assess hotspots using molecular dynamics (MD) simulations. MD simulations integrate protein flexibility and the complicated role of water, thereby providing a more realistic assessment of the complex kinetics and thermodynamics at play. In this review, we describe the evolution of various cosolvent-based MD techniques and highlight a myriad of potential applications for such technologies in computational drug development.
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Affiliation(s)
- Phani Ghanakota
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109-1065, United States
| | - Heather A Carlson
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109-1065, United States
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11
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Ung PMU, Ghanakota P, Graham SE, Lexa KW, Carlson HA. Identifying binding hot spots on protein surfaces by mixed-solvent molecular dynamics: HIV-1 protease as a test case. Biopolymers 2016; 105:21-34. [PMID: 26385317 DOI: 10.1002/bip.22742] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/14/2015] [Accepted: 09/14/2015] [Indexed: 12/16/2022]
Abstract
Mixed-solvent molecular dynamics (MixMD) simulations use full protein flexibility and competition between water and small organic probes to achieve accurate hot-spot mapping on protein surfaces. In this study, we improved MixMD using human immunodeficiency virus type-1 protease (HIVp) as the test case. We used three probe-water solutions (acetonitrile-water, isopropanol-water, and pyrimidine-water), first at 50% w/w concentration and later at 5% v/v. Paradoxically, better mapping was achieved by using fewer probes; 5% simulations gave a superior signal-to-noise ratio and far fewer spurious hot spots than 50% MixMD. Furthermore, very intense and well-defined probe occupancies were observed in the catalytic site and potential allosteric sites that have been confirmed experimentally. The Eye site, an allosteric site underneath the flap of HIVp, has been confirmed by the presence of a 5-nitroindole fragment in a crystal structure. MixMD also mapped two additional hot spots: the Exo site (between the Gly16-Gly17 and Cys67-Gly68 loops) and the Face site (between Glu21-Ala22 and Val84-Ile85 loops). The Exo site was observed to overlap with crystallographic additives such as acetate and dimethyl sulfoxide that are present in different crystal forms of the protein. Analysis of crystal structures of HIVp in different symmetry groups has shown that some surface sites are common interfaces for crystal contacts, which means that they are surfaces that are relatively easy to desolvate and complement with organic molecules. MixMD should identify these sites; in fact, their occupancy values help establish a solid cut-off where "druggable" sites are required to have higher occupancies than the crystal-packing faces.
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Affiliation(s)
- Peter M U Ung
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065
| | - Phani Ghanakota
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065
| | - Sarah E Graham
- Department of Biophysics, College of LSA, University of Michigan, 930 N. University St., Ann Arbor, MI, 48109-1055
| | - Katrina W Lexa
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065
| | - Heather A Carlson
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church St., Ann Arbor, MI, 48109-1065.,Department of Biophysics, College of LSA, University of Michigan, 930 N. University St., Ann Arbor, MI, 48109-1055
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12
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Ung PMU, Dunbar JB, Gestwicki JE, Carlson HA. An allosteric modulator of HIV-1 protease shows equipotent inhibition of wild-type and drug-resistant proteases. J Med Chem 2014; 57:6468-78. [PMID: 25062388 PMCID: PMC4136727 DOI: 10.1021/jm5008352] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
![]()
NMR
and MD simulations have demonstrated that the flaps of HIV-1 protease
(HIV-1p) adopt a range of conformations that are coupled with its
enzymatic activity. Previously, a model was created for an allosteric
site located between the flap and the core of HIV-1p, called the Eye
site (Biopolymers2008, 89, 643−65218381626). Here, results from our first study were
combined with a ligand-based, lead-hopping method to identify a novel
compound (NIT). NIT inhibits HIV-1p, independent of the presence of
an active-site inhibitor such as pepstatin A. Assays showed that NIT
acts on an allosteric site other than the dimerization interface.
MD simulations of the ligand–protein complex show that NIT
stably binds in the Eye site and restricts the flaps. That bound state
of NIT is consistent with a crystal structure of similar fragments
bound in the Eye site (Chem.
Biol. Drug Des.2010, 75, 257−26820659109). Most importantly,
NIT is equally potent against wild-type and a multidrug-resistant
mutant of HIV-1p, which highlights the promise of allosteric inhibitors
circumventing existing clinical resistance.
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Affiliation(s)
- Peter M-U Ung
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan , 428 Church Street, Ann Arbor, Michigan 48109-1065, United States
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13
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Lexa KW, Goh GB, Carlson HA. Parameter choice matters: validating probe parameters for use in mixed-solvent simulations. J Chem Inf Model 2014; 54:2190-9. [PMID: 25058662 PMCID: PMC4144759 DOI: 10.1021/ci400741u] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Probe mapping is a common approach
for identifying potential binding
sites in structure-based drug design; however, it typically relies
on energy minimizations of probes in the gas phase and a static protein
structure. The mixed-solvent molecular dynamics (MixMD) approach was
recently developed to account for full protein flexibility and solvation
effects in hot-spot mapping. Our first study used only acetonitrile
as a probe, and here, we have augmented the set of functional group
probes through careful testing and parameter validation. A diverse
range of probes are needed in order to map complex binding interactions.
A small variation in probe parameters can adversely effect mixed-solvent
behavior, which we highlight with isopropanol. We tested 11 solvents
to identify six with appropriate behavior in TIP3P water to use as
organic probes in the MixMD method. In addition to acetonitrile and
isopropanol, we have identified acetone, N-methylacetamide,
imidazole, and pyrimidine. These probe solvents will enable MixMD
studies to recover hydrogen-bonding sites, hydrophobic pockets, protein–protein
interactions, and aromatic hotspots. Also, we show that ternary-solvent
systems can be incorporated within a single simulation. Importantly,
these binary and ternary solvents do not require artificial repulsion
terms like other methods. Within merely 5 ns, layered solvent boxes
become evenly mixed for soluble probes. We used radial distribution
functions to evaluate solvent behavior, determine adequate mixing,
and confirm the absence of phase separation. We recommend that radial
distribution functions should be used to assess adequate sampling
in all mixed-solvent techniques rather than the current practice of
examining the solvent ratios at the edges of the solvent box.
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Affiliation(s)
- Katrina W Lexa
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor , 428 Church St., Ann Arbor, Michigan 48109-1065, United States
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14
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Trypanosoma cruzi trans-sialidase as a drug target against Chagas disease (American trypanosomiasis). Future Med Chem 2014; 5:1889-900. [PMID: 24144418 DOI: 10.4155/fmc.13.129] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Chagas disease (or American trypanosomiasis) is a deadly tropical disease that affects millions of people worldwide, primarily in rural regions of South America. Trypanosoma cruzi, the parasitic cause of Chagas disease, possesses a membrane-anchored trans-sialidase enzyme that transfers sialic acids from the host cell surface to the parasitic cell surface, allowing T. cruzi to effectively evade the host's immune system. This enzyme has no analogous human counterpart and thus has become an interesting drug target to combat the parasite. Recent computational efforts have improved our knowledge about the enzyme's structure, dynamics and catalyzed reaction. Many compounds have been tested against trans-sialidase activity, but no strong inhibitors have been identified yet. The current lack of drugs for Chagas disease necessitates more R&D into the design and discovery of strong inhibitors of T. cruzi trans-sialidase.
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15
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Moonsamy S, Soliman MES. Dual acting HIV inhibitors: integrated rational in silico design strategy. Med Chem Res 2013. [DOI: 10.1007/s00044-013-0670-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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16
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Abstract
Structure-based drug design has become an essential tool for rapid lead discovery and optimization. As available structural information has increased, researchers have become increasingly aware of the importance of protein flexibility for accurate description of the native state. Typical protein-ligand docking efforts still rely on a single rigid receptor, which is an incomplete representation of potential binding conformations of the protein. These rigid docking efforts typically show the best performance rates between 50 and 75%, while fully flexible docking methods can enhance pose prediction up to 80-95%. This review examines the current toolbox for flexible protein-ligand docking and receptor surface mapping. Present limitations and possibilities for future development are discussed.
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Affiliation(s)
- Katrina W. Lexa
- Department of Medicinal Chemistry, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
| | - Heather A. Carlson
- Department of Medicinal Chemistry, University of Michigan, 428 Church Street, Ann Arbor, MI 48109-1065, USA
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17
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Verspoor KM, Cohn JD, Ravikumar KE, Wall ME. Text mining improves prediction of protein functional sites. PLoS One 2012; 7:e32171. [PMID: 22393388 PMCID: PMC3290545 DOI: 10.1371/journal.pone.0032171] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Accepted: 01/20/2012] [Indexed: 11/20/2022] Open
Abstract
We present an approach that integrates protein structure analysis and text mining for protein functional site prediction, called LEAP-FS (Literature Enhanced Automated Prediction of Functional Sites). The structure analysis was carried out using Dynamics Perturbation Analysis (DPA), which predicts functional sites at control points where interactions greatly perturb protein vibrations. The text mining extracts mentions of residues in the literature, and predicts that residues mentioned are functionally important. We assessed the significance of each of these methods by analyzing their performance in finding known functional sites (specifically, small-molecule binding sites and catalytic sites) in about 100,000 publicly available protein structures. The DPA predictions recapitulated many of the functional site annotations and preferentially recovered binding sites annotated as biologically relevant vs. those annotated as potentially spurious. The text-based predictions were also substantially supported by the functional site annotations: compared to other residues, residues mentioned in text were roughly six times more likely to be found in a functional site. The overlap of predictions with annotations improved when the text-based and structure-based methods agreed. Our analysis also yielded new high-quality predictions of many functional site residues that were not catalogued in the curated data sources we inspected. We conclude that both DPA and text mining independently provide valuable high-throughput protein functional site predictions, and that integrating the two methods using LEAP-FS further improves the quality of these predictions.
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Affiliation(s)
- Karin M. Verspoor
- University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Judith D. Cohn
- Computer, Computational, and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
| | - Komandur E. Ravikumar
- University of Colorado School of Medicine, Aurora, Colorado, United States of America
| | - Michael E. Wall
- Computer, Computational, and Statistical Sciences Division, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
- Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, New Mexico, United States of America
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18
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Yan GW, Chen Y, Li Y, Chen HF. Revealing interaction mode between HIV-1 protease and mannitol analog inhibitor. Chem Biol Drug Des 2012; 79:916-25. [PMID: 22296911 DOI: 10.1111/j.1747-0285.2012.01348.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
HIV protease is a key enzyme to play a key role in the HIV-1 replication cycle and control the maturation from HIV viruses to an infectious virion. HIV-1 protease has become an important target for anti-HIV-1 drug development. Here, we used molecular dynamics simulation to study the binding mode between mannitol derivatives and HIV-1 protease. The results suggest that the most active compound (M35) has more stable hydrogen bonds and stable native contacts than the less active one (M17). These mannitol derivatives might have similar interaction mode with HIV-1 protease. Then, 3D-QSAR was used to construct quantitative structure-activity models. The cross-validated q(2) values are found as 0.728 and 0.611 for CoMFA and CoMSIA, respectively. And the non-cross-validated r(2) values are 0.973 and 0.950. Nine test set compounds validate the model. The results show that this model possesses better prediction ability than the previous work. This model can be used to design new chemical entities and make quantitative prediction of the bioactivities for HIV-1 protease inhibitors before resorting to in vitro and in vivo experiment.
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Affiliation(s)
- Guan-Wen Yan
- State Key Laboratory of Microbial metabolism, Department of Bioinformatics and Biostatistics, College of Life Sciences and Biotechnology, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China
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19
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Schuyler AD, Carlson HA, Feldman EL. Computational methods for identifying a layered allosteric regulatory mechanism for ALS-causing mutations of Cu-Zn superoxide dismutase 1. Proteins 2011; 79:417-27. [PMID: 21104697 DOI: 10.1002/prot.22892] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The most prominent form of familial amyotrophic lateral sclerosis (fALS, Lou Gehrig's Disease) is caused by mutations of Cu-Zn superoxide dismutase 1 (SOD1). SOD1 maintains antioxidant activity under fALS causing mutations, suggesting that the mutations introduce a new, toxic, function. There are 100+ such known mutations that are chemically diverse and spatially distributed across the structure. The common phenotype leads us to propose an allosteric regulatory mechanism hypothesis: SOD1 mutants alter the correlated dynamics of the structure and differentially signal across an inherent allosteric network, thereby driving the disease mechanism at varying rates of efficiency. Two recently developed computational methods for identifying allosteric control sites are applied to the wild type crystal structure, 4 fALS mutant crystal structures, 20 computationally generated fALS mutants and 1 computationally generated non-fALS mutant. The ensemble of mutant structures is used to generate an ensemble of dynamics, from which two allosteric control networks are identified. One network is connected to the catalytic site and thus may be involved in the natural antioxidant function. The second allosteric control network has a locus bordering the dimer interface and thus may serve as a mechanism to modulate dimer stability. Though the toxic function of mutated SOD1 is unknown and likely due to several contributing factors, this study explains how diverse mutations give rise to a common function. This new paradigm for allostery controlled function has broad implications across allosteric systems and may lead to the identification of the key chemical activity of SOD1-linked ALS.
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Affiliation(s)
- Adam D Schuyler
- Department of Molecular, Microbial and Structural Biology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
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20
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Deng NJ, Zheng W, Gallicchio E, Levy RM. Insights into the dynamics of HIV-1 protease: a kinetic network model constructed from atomistic simulations. J Am Chem Soc 2011; 133:9387-94. [PMID: 21561098 DOI: 10.1021/ja2008032] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational dynamics in the flaps of HIV-1 protease plays a crucial role in the mechanism of substrate binding. We develop a kinetic network model, constructed from detailed atomistic simulations, to determine the kinetic mechanisms of the conformational transitions in HIV-1 PR. To overcome the time scale limitation of conventional molecular dynamics (MD) simulations, our method combines replica exchange MD with transition path theory (TPT) to study the diversity and temperature dependence of the pathways connecting functionally important states of the protease. At low temperatures the large-scale flap opening is dominated by a small number of paths; at elevated temperatures the transition occurs through many structurally heterogeneous routes. The expanded conformation in the crystal structure 1TW7 is found to closely mimic a key intermediate in the flap-opening pathways at low temperature. We investigated the different transition mechanisms between the semi-open and closed forms. The calculated relaxation times reveal fast semi-open ↔ closed transitions, and infrequently the flaps fully open. The ligand binding rate predicted from this kinetic model increases by 38-fold from 285 to 309 K, which is in general agreement with experiments. To our knowledge, this is the first application of a network model constructed from atomistic simulations together with TPT to analyze conformational changes between different functional states of a natively folded protein.
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Affiliation(s)
- Nan-jie Deng
- BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers, the State University of New Jersey, Piscataway, New Jersey 08854, USA
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21
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Lexa KW, Carlson HA. Binding to the open conformation of HIV-1 protease. Proteins 2011; 79:2282-90. [PMID: 21604303 DOI: 10.1002/prot.23054] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 03/21/2011] [Accepted: 03/31/2011] [Indexed: 11/08/2022]
Abstract
A recent crystal structure of HIV-1 protease (HIVp) was the first to experimentally observe a ligand targeting an open-flap conformation. Researchers studying a symmetric pyrrolidine inhibitor found that two ligands cocrystallized with the protease, forcing an unusual configuration and unique crystallographic contacts. One molecule is centered in the traditional binding site (α pose) and the other binds between the flaps (β pose). The ligands stack against each other in a region termed the "eye" site. Ligands bound to the eye site should prevent flap closure, but it is unclear if the pyrrolidine inhibitors or the crystal packing are causing the open state. Molecular dynamics simulations were used to examine the solution-state behavior of three possible binding modes: the ternary complex of HIVp+αβ and the binary complexes, HIVp+α and HIVp+β. We show that HIVp+α is the most stable of the three states. During conformational sampling, α takes an asymmetric binding pose, with one naphthyl ring occupying the eye site and the other reoriented down to occupy positions seen with traditional inhibitors. This finding supports previous studies that reveal a requirement for asymmetric binding at the eye site. In fact, if the α pose is modified to splay both naphthyl rings across the binding site like traditional inhibitors, one ring consistently flips to occupy the eye site. Our simulations reveal that interactions to the eye site encourage a conformationally restrained state, and understanding those contacts may aid the design of ligands to specifically target alternate conformations of the protease.
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Affiliation(s)
- Katrina W Lexa
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1065, USA
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22
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Markt P, Schuster D, Langer T. Pharmacophore Models for Virtual Screening. METHODS AND PRINCIPLES IN MEDICINAL CHEMISTRY 2011. [DOI: 10.1002/9783527633326.ch5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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23
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Lexa KW, Carlson HA. Full protein flexibility is essential for proper hot-spot mapping. J Am Chem Soc 2010; 133:200-2. [PMID: 21158470 DOI: 10.1021/ja1079332] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A traditional technique for structure-based drug design (SBDD) is mapping of protein surfaces with probe molecules to identify "hot spots" where key functional groups can best complement the receptor. Common methods, such as minimization of probes or calculation of grids, use a fixed protein structure in the gas phase, ignoring both protein flexibility and proper competition between the probes and water. As a result, the potential surface is quite rugged, and many spurious local minima are identified. In this work, we compared rigid and fully flexible proteins in mixed-solvent molecular dynamics, which allows for flexibility and full solvent effects. We were surprised to find that the large number of local minima are still found when a protein's conformational sampling is restricted; the dynamic averaging of probes and competition with water do not smooth the potential surface as one might expect. Only when a protein is allowed to be fully flexible in the simulation are the proper minima located and the spurious ones eliminated. Our results indicate that inclusion of full protein flexibility is critical to accurate hot-spot mapping for SBDD.
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Affiliation(s)
- Katrina W Lexa
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1065, United States
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24
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Shen CH, Wang YF, Kovalevsky AY, Harrison RW, Weber IT. Amprenavir complexes with HIV-1 protease and its drug-resistant mutants altering hydrophobic clusters. FEBS J 2010; 277:3699-714. [PMID: 20695887 DOI: 10.1111/j.1742-4658.2010.07771.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The structural and kinetic effects of amprenavir (APV), a clinical HIV protease (PR) inhibitor, were analyzed with wild-type enzyme and mutants with single substitutions of V32I, I50V, I54V, I54M, I84V and L90M that are common in drug resistance. Crystal structures of the APV complexes at resolutions of 1.02-1.85 Å reveal the structural changes due to the mutations. Substitution of the larger side chains in PR(V32I) , PR(I54M) and PR(L90M) resulted in the formation of new hydrophobic contacts with flap residues, residues 79 and 80, and Asp25, respectively. Mutation to smaller side chains eliminated hydrophobic interactions in the PR(I50V) and PR(I54V) structures. The PR(I84V)-APV complex had lost hydrophobic contacts with APV, the PR(V32I)-APV complex showed increased hydrophobic contacts within the hydrophobic cluster and the PR(I50V) complex had weaker polar and hydrophobic interactions with APV. The observed structural changes in PR(I84V)-APV, PR(V32I)-APV and PR(I50V)-APV were related to their reduced inhibition by APV of six-, 10- and 30-fold, respectively, relative to wild-type PR. The APV complexes were compared with the corresponding saquinavir complexes. The PR dimers had distinct rearrangements of the flaps and 80's loops that adapt to the different P1' groups of the inhibitors, while maintaining contacts within the hydrophobic cluster. These small changes in the loops and weak internal interactions produce the different patterns of resistant mutations for the two drugs.
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Affiliation(s)
- Chen-Hsiang Shen
- Department of Biology, Molecular Basis of Disease Program, Georgia State University, Atlanta, GA, USA
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25
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Identification of broad-based HIV-1 protease inhibitors from combinatorial libraries. Biochem J 2010; 429:527-32. [PMID: 20507280 DOI: 10.1042/bj20091645] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Clinically approved inhibitors of the HIV-1 protease function via a competitive mechanism. A particular vulnerability of competitive inhibitors is their sensitivity to increases in substrate concentration, as may occur during virion assembly, budding and processing into a mature infectious viral particle. Advances in chemical synthesis have led to the development of new high-diversity chemical libraries using rapid in-solution syntheses. These libraries have been shown previously to be effective at disrupting protein-protein and protein-nucleic acid interfaces. We have screened 44000 compounds from such a library to identify inhibitors of the HIV-1 protease. One compound was identified that inhibits wild-type protease, as well as a drug-resistant protease with six mutations. Moreover, analysis of this compound suggests an allosteric non-competitive mechanism of inhibition and may represent a starting point for an additional strategy for anti-retroviral therapy.
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26
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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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27
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Chen Y, Pohlhaus DT. In silico docking and scoring of fragments. DRUG DISCOVERY TODAY. TECHNOLOGIES 2010; 7:e147-e202. [PMID: 24103766 DOI: 10.1016/j.ddtec.2010.11.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
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28
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Approaches to the design of HIV protease inhibitors with improved resistance profiles. Curr Opin HIV AIDS 2009; 3:633-41. [PMID: 19373035 DOI: 10.1097/coh.0b013e328313911d] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
PURPOSE OF REVIEW This review describes current approaches to HIV protease inhibitor design, with a focus on improving their profile against drug-resistant mutants. Potential explanations for the flat resistance profile of some potent protease inhibitors and discrepancies between the apparent fold change of potency at the enzyme level and in cell-based assays are discussed. RECENT FINDINGS Despite new ideas and a clear rationale for designing inhibitors that bind outside the enzyme active site, all current protease inhibitors with potent antiviral activity target this site. Several bis-tetrahydrofuran-containing compounds including darunavir, brecanavir, GS-8374, and Sequoia protease inhibitors exhibit excellent potency against mutant HIV strains that are resistant to clinically used protease inhibitors. The apparently flat resistance profiles of these and some other protease inhibitors may, at least in part, be explained by their high potency against wild-type enzyme. The substrate envelope and solvent-anchoring hypotheses have been used to design and/or rationalize improved resistance profiles. Traditional approaches yielded a lysine sulfonamide PL-100 with a unique resistance profile. SUMMARY Several theories on how to design HIV protease inhibitors with improved resistance profiles have been proposed during the review period. The general concepts that are incorporated into most design strategies include maximizing the interactions with the backbone and conserved side chains of the enzyme while minimizing inhibitor size and maintaining conformational flexibility to allow for modified binding modes.
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29
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Demir Ö, Roitberg AE. Modulation of catalytic function by differential plasticity of the active site: case study of Trypanosoma cruzi trans-sialidase and Trypanosoma rangeli sialidase. Biochemistry 2009; 48:3398-406. [PMID: 19216574 PMCID: PMC2713503 DOI: 10.1021/bi802230y] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
trans-Sialidase is an essential enzyme for Trypanosoma cruzi, the causative agent of Chagas' disease, to escape from the host immune system and to invade the host cells. Therefore, T. cruzi trans-sialidase (TcTS) presents a potential and appealing therapeutic target for this lethal disease. The availability of a structurally very similar enzyme with strict hydrolase activity (Trypanosoma rangeli sialidase, TrSA) provides us a unique opportunity to understand the determinants of their structure and catalytic mechanism. In this study, we compare the catalytic cleft plasticity of free (apo) and ligand-bound (holo) forms of the two enzymes using molecular dynamics simulations. We focus on the mouth of the catalytic cleft that is defined by two residues: W312 and Y119 in TcTS and W312 and S119 in TrSA. Our results indicate that TcTS has a very flexible, widely open catalytic cleft, mostly due to W312 loop motion, in apo form. However, when the catalytic cleft is occupied by a ligand, the flexibility and solvent exposure of TcTS is significantly reduced. On the other hand, TrSA maintains a more open catalytic cleft compared to its crystal structures in both apo and holo forms (and compared to TcTS in holo forms). The reduced solvent exposure of TcTS catalytic cleft might be partially or fully responsible for TcTS to be a less efficient hydrolase than TrSA.
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Affiliation(s)
- Özlem Demir
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-8435, USA
- Quantum Theory Project, University of Florida, Gainesville, Florida 32611-8435, USA
| | - Adrian E. Roitberg
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-8435, USA
- Quantum Theory Project, University of Florida, Gainesville, Florida 32611-8435, USA
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30
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Yu X, Wang Q, Yang JC, Buch I, Tsai CJ, Ma B, Cheng SZD, Nussinov R, Zheng J. Mutational analysis and allosteric effects in the HIV-1 capsid protein carboxyl-terminal dimerization domain. Biomacromolecules 2009; 10:390-9. [PMID: 19199580 PMCID: PMC2651736 DOI: 10.1021/bm801151r] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The carboxyl-terminal domain (CTD, residues 146-231) of the HIV-1 capsid (CA) protein plays an important role in the CA-CA dimerization and viral assembly of the human immunodeficiency virus type 1. Disrupting the native conformation of the CA is essential for blocking viral capsid formation and viral replication. Thus, it is important to identify the exact nature of the structural changes and driving forces of the CTD dimerization that take place in mutant forms. Here, we compare the structural stability, conformational dynamics, and association force of the CTD dimers for both wild-type and mutated sequences using all-atom explicit-solvent molecular dynamics (MD). The simulations show that Q155N and E159D at the major homology region (MHR) and W184A and M185A at the helix 2 region are energetically less favorable than the wild-type, imposing profound negative effects on intermolecular CA-CA dimerization. Detailed structural analysis shows that three mutants (Q155N, E159D, and W184A) display much more flexible local structures and weaker CA-CA association than the wildtype, primarily due to the loss of interactions (hydrogen bonds, side chain hydrophobic contacts, and pi-stacking) with their neighboring residues. Most interestingly, the MHR that is far from the interacting dimeric interface is more sensitive to the mutations than the helix 2 region that is located at the CA-CA dimeric interface, indicating that structural changes in the distinct motif of the CA could similarly allosterically prevent the CA capsid formation. In addition, the structural and free energy comparison of the five residues shorter CA (151-231) dimer with the CA (146-231) dimer further indicates that hydrophobic interactions, side chain packing, and hydrogen bonds are the major, dominant driving forces in stabilizing the CA interface.
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Affiliation(s)
- Xiang Yu
- Department of Chemical and Biomolecular Engineering, The University of Akron, Akron, Ohio 44325, USA
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31
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Lexa KW, Damm KL, Quintero JJ, Gestwicki JE, Carlson HA. Clarifying allosteric control of flap conformations in the 1TW7 crystal structure of HIV-1 protease. Proteins 2009; 74:872-80. [PMID: 18704936 DOI: 10.1002/prot.22195] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The 1TW7 crystal structure of HIV-1 protease shows the flaps placed wider and more open than what is seen in other examples of the semi-open, apo form. It has been proposed that this might be experimental evidence of allosteric control, because crystal packing creates contacts to the "elbow region" of the protease, which may cause deformation of the flaps. Recent dynamics simulations have shown that the conformation seen in 1TW7 relaxes into the typical semi-open conformation in the absence of the crystal contacts, definitively showing that the crystal contacts cause the deformation (Layten et al., J Am Chem Soc 2006;128:13360-13361). However, this does not prove or disprove allosteric modulation at the elbow. In this study, we have conducted additional simulations, supplemented with experimental testing, to further probe the possibility of 1TW7 providing an example of allosteric control of the flap region. We show that the contacts are unstable and do not restrict the conformational sampling of the flaps. The deformation seen in the 1TW7 crystal structure is simply opportunistic crystal packing and not allosteric control.
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Affiliation(s)
- Katrina W Lexa
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1065, USA
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32
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Lerner MG, Meagher KL, Carlson HA. Automated clustering of probe molecules from solvent mapping of protein surfaces: new algorithms applied to hot-spot mapping and structure-based drug design. J Comput Aided Mol Des 2008; 22:727-36. [PMID: 18679808 PMCID: PMC2856601 DOI: 10.1007/s10822-008-9231-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2008] [Accepted: 07/21/2008] [Indexed: 10/21/2022]
Abstract
Use of solvent mapping, based on multiple-copy minimization (MCM) techniques, is common in structure-based drug discovery. The minima of small-molecule probes define locations for complementary interactions within a binding pocket. Here, we present improved methods for MCM. In particular, a Jarvis-Patrick (JP) method is outlined for grouping the final locations of minimized probes into physical clusters. This algorithm has been tested through a study of protein-protein interfaces, showing the process to be robust, deterministic, and fast in the mapping of protein "hot spots." Improvements in the initial placement of probe molecules are also described. A final application to HIV-1 protease shows how our automated technique can be used to partition data too complicated to analyze by hand. These new automated methods may be easily and quickly extended to other protein systems, and our clustering methodology may be readily incorporated into other clustering packages.
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Affiliation(s)
- Michael G. Lerner
- Department of Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Kristin L. Meagher
- Department of Medicinal Chemistry, College of Pharmacy, 418 Church St., University of Michigan, Ann Arbor, Michigan 48109-1065
| | - Heather A. Carlson
- Department of Biophysics, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
- Department of Medicinal Chemistry, College of Pharmacy, 418 Church St., University of Michigan, Ann Arbor, Michigan 48109-1065
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