1
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K C Y, Pal S, Nitz TJ, Wild C, Gaur R. Construction of a HIV-1 subtype C 3D model using homology modeling and in-silico docking, molecular dynamics simulation, and MM-GBSA calculation of second-generation HIV-1 maturation inhibitor(s). J Biomol Struct Dyn 2024; 42:7150-7159. [PMID: 37489057 DOI: 10.1080/07391102.2023.2238079] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 07/13/2023] [Indexed: 07/26/2023]
Abstract
Maturation inhibitors (MIs) efficiently block HIV-1 maturation by inhibiting the cleavage of the capsid protein and spacer peptide 1 (CA-SP1) leading to the production of immature and non-infectious virus particles. We have previously reported that second-generation MIs were more potent than bevirimat (BVM) against HIV-1 subtype C. In-silico studies on interaction of with BVM and their analogs have been limited to HIV-1 subtype B(5I4T) due to lack of an available 3D structure for HIV-1 subtype C virus. In our current study, we have developed a 3D model of HIV-1C Gag CA-SP1 region using protein homology modeling with HIV-1 subtype B(514T) as a template. The HIV-1 C homology model generated was extensively validated using several online tools and served as a template to perform molecular docking studies with eight well-characterized MIs. The docked complex of HIV-1C and all nine MIs was subjected to molecular dynamics simulation for 100 ns using AMBER and binding free energy calculations were done using MM-GBSA. Based on our data, CV8611 exhibited highest binding energy of -6.5 Kcal/mol among all BVM analogs. CV8611 formed strong interactions with Gly222 and Met235 of HIV-1C Gag CA-SP1 during MD simulation and remained intact. The root mean square deviation and root mean square fluctuation values of the complex were stable during the simulations. Our study is the first to report construction and validation of 3D model for the HIV-1C Gag CA-SP1, which could serve as a crucial tool in the structure-aided design of novel and broadly acting maturation inhibitors.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Yuvraj K C
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
| | - Sapna Pal
- Bioinformatics centre, National Institute of Immunology, New Delhi, India
| | - T J Nitz
- DFH Pharma, Gaithersburg, MD, USA
| | | | - Ritu Gaur
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
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2
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Qian Y, Evans D, Mishra B, Fu Y, Liu ZH, Guo S, Johnson ME. Temporal control by cofactors prevents kinetic trapping in retroviral Gag lattice assembly. Biophys J 2023; 122:3173-3190. [PMID: 37393432 PMCID: PMC10432227 DOI: 10.1016/j.bpj.2023.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/03/2023] Open
Abstract
For retroviruses like HIV to proliferate, they must form virions shaped by the self-assembly of Gag polyproteins into a rigid lattice. This immature Gag lattice has been structurally characterized and reconstituted in vitro, revealing the sensitivity of lattice assembly to multiple cofactors. Due to this sensitivity, the energetic criterion for forming stable lattices is unknown, as are their corresponding rates. Here, we use a reaction-diffusion model designed from the cryo-ET structure of the immature Gag lattice to map a phase diagram of assembly outcomes controlled by experimentally constrained rates and free energies, over experimentally relevant timescales. We find that productive assembly of complete lattices in bulk solution is extraordinarily difficult due to the large size of this ∼3700 monomer complex. Multiple Gag lattices nucleate before growth can complete, resulting in loss of free monomers and frequent kinetic trapping. We therefore derive a time-dependent protocol to titrate or "activate" the Gag monomers slowly within the solution volume, mimicking the biological roles of cofactors. This general strategy works remarkably well, yielding productive growth of self-assembled lattices for multiple interaction strengths and binding rates. By comparing to the in vitro assembly kinetics, we can estimate bounds on rates of Gag binding to Gag and the cellular cofactor IP6. Our results show that Gag binding to IP6 can provide the additional time delay necessary to support smooth growth of the immature lattice with relatively fast assembly kinetics, mostly avoiding kinetic traps. Our work provides a foundation for predicting and disrupting formation of the immature Gag lattice via targeting specific protein-protein binding interactions.
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Affiliation(s)
- Yian Qian
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Daniel Evans
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Bhavya Mishra
- Department of Physics, and Center for Cellular and Biomolecular Machines, University of California, Merced, California
| | - Yiben Fu
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Zixiu Hugh Liu
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Sikao Guo
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland.
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3
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Guo S, Saha I, Saffarian S, Johnson ME. Structure of the HIV immature lattice allows for essential lattice remodeling within budded virions. eLife 2023; 12:e84881. [PMID: 37435945 PMCID: PMC10361719 DOI: 10.7554/elife.84881] [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: 11/12/2022] [Accepted: 07/12/2023] [Indexed: 07/13/2023] Open
Abstract
For HIV virions to become infectious, the immature lattice of Gag polyproteins attached to the virion membrane must be cleaved. Cleavage cannot initiate without the protease formed by the homo-dimerization of domains linked to Gag. However, only 5% of the Gag polyproteins, termed Gag-Pol, carry this protease domain, and they are embedded within the structured lattice. The mechanism of Gag-Pol dimerization is unknown. Here, we use spatial stochastic computer simulations of the immature Gag lattice as derived from experimental structures, showing that dynamics of the lattice on the membrane is unavoidable due to the missing 1/3 of the spherical protein coat. These dynamics allow for Gag-Pol molecules carrying the protease domains to detach and reattach at new places within the lattice. Surprisingly, dimerization timescales of minutes or less are achievable for realistic binding energies and rates despite retaining most of the large-scale lattice structure. We derive a formula allowing extrapolation of timescales as a function of interaction free energy and binding rate, thus predicting how additional stabilization of the lattice would impact dimerization times. We further show that during assembly, dimerization of Gag-Pol is highly likely and therefore must be actively suppressed to prevent early activation. By direct comparison to recent biochemical measurements within budded virions, we find that only moderately stable hexamer contacts (-12kBT<∆G<-8kBT) retain both the dynamics and lattice structures that are consistent with experiment. These dynamics are likely essential for proper maturation, and our models quantify and predict lattice dynamics and protease dimerization timescales that define a key step in understanding formation of infectious viruses.
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Affiliation(s)
- Sikao Guo
- TC Jenkins Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Ipsita Saha
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of HealthFrederickUnited States
| | - Saveez Saffarian
- Center for Cell and Genome Science, University of UtahSalt Lake CityUnited States
- Department of Physics and Astronomy, University of UtahSalt Lake CityUnited States
- School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
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4
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Kleinpeter AB, Zhu Y, Mallery DL, Ablan SD, Chen L, Hardenbrook N, Saiardi A, James LC, Zhang P, Freed EO. The Effect of Inositol Hexakisphosphate on HIV-1 Particle Production and Infectivity can be Modulated by Mutations that Affect the Stability of the Immature Gag Lattice. J Mol Biol 2023; 435:168037. [PMID: 37330292 PMCID: PMC10544863 DOI: 10.1016/j.jmb.2023.168037] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 02/24/2023] [Accepted: 02/25/2023] [Indexed: 06/19/2023]
Abstract
The assembly of an HIV-1 particle begins with the construction of a spherical lattice composed of hexamer subunits of the Gag polyprotein. The cellular metabolite inositol hexakisphosphate (IP6) binds and stabilizes the immature Gag lattice via an interaction with the six-helix bundle (6HB), a crucial structural feature of Gag hexamers that modulates both virus assembly and infectivity. The 6HB must be stable enough to promote immature Gag lattice formation, but also flexible enough to be accessible to the viral protease, which cleaves the 6HB during particle maturation. 6HB cleavage liberates the capsid (CA) domain of Gag from the adjacent spacer peptide 1 (SP1) and IP6 from its binding site. This pool of IP6 molecules then promotes the assembly of CA into the mature conical capsid that is required for infection. Depletion of IP6 in virus-producer cells results in severe defects in assembly and infectivity of wild-type (WT) virions. Here we show that in an SP1 double mutant (M4L/T8I) with a hyperstable 6HB, IP6 can block virion infectivity by preventing CA-SP1 processing. Thus, depletion of IP6 in virus-producer cells markedly increases M4L/T8I CA-SP1 processing and infectivity. We also show that the introduction of the M4L/T8I mutations partially rescues the assembly and infectivity defects induced by IP6 depletion on WT virions, likely by increasing the affinity of the immature lattice for limiting IP6. These findings reinforce the importance of the 6HB in virus assembly, maturation, and infection and highlight the ability of IP6 to modulate 6HB stability.
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Affiliation(s)
- Alex B Kleinpeter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA. https://twitter.com/AlexKleinpeter
| | - Yanan Zhu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Donna L Mallery
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Sherimay D Ablan
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Long Chen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Nathan Hardenbrook
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Adolfo Saiardi
- Laboratory for Molecular Cell Biology, University College London, London, UK. https://twitter.com/SaiardiLab
| | - Leo C James
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK. https://twitter.com/JamesLab9
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK; Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, UK
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA.
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5
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Sarkar S, Zadrozny KK, Zadorozhnyi R, Russell RW, Quinn CM, Kleinpeter A, Ablan S, Meshkin H, Perilla JR, Freed EO, Ganser-Pornillos BK, Pornillos O, Gronenborn AM, Polenova T. Structural basis of HIV-1 maturation inhibitor binding and activity. Nat Commun 2023; 14:1237. [PMID: 36871077 PMCID: PMC9985623 DOI: 10.1038/s41467-023-36569-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Accepted: 02/03/2023] [Indexed: 03/06/2023] Open
Abstract
HIV-1 maturation inhibitors (MIs), Bevirimat (BVM) and its analogs interfere with the catalytic cleavage of spacer peptide 1 (SP1) from the capsid protein C-terminal domain (CACTD), by binding to and stabilizing the CACTD-SP1 region. MIs are under development as alternative drugs to augment current antiretroviral therapies. Although promising, their mechanism of action and associated virus resistance pathways remain poorly understood at the molecular, biochemical, and structural levels. We report atomic-resolution magic-angle-spinning NMR structures of microcrystalline assemblies of CACTD-SP1 complexed with BVM and/or the assembly cofactor inositol hexakisphosphate (IP6). Our results reveal a mechanism by which BVM disrupts maturation, tightening the 6-helix bundle pore and quenching the motions of SP1 and the simultaneously bound IP6. In addition, BVM-resistant SP1-A1V and SP1-V7A variants exhibit distinct conformational and binding characteristics. Taken together, our study provides a structural explanation for BVM resistance as well as guidance for the design of new MIs.
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Affiliation(s)
- Sucharita Sarkar
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Kaneil K Zadrozny
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Roman Zadorozhnyi
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Ryan W Russell
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Alex Kleinpeter
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Sherimay Ablan
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Hamed Meshkin
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Eric O Freed
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702-1201, USA
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
| | - Angela M Gronenborn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
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6
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Smith RA, Raugi DN, Nixon RS, Song J, Seydi M, Gottlieb GS. Intrinsic resistance of HIV-2 and SIV to the maturation inhibitor GSK2838232. PLoS One 2023; 18:e0280568. [PMID: 36652466 PMCID: PMC9847912 DOI: 10.1371/journal.pone.0280568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
GSK2838232 (GSK232) is a novel maturation inhibitor that blocks the proteolytic cleavage of HIV-1 Gag at the junction of capsid and spacer peptide 1 (CA/SP1), rendering newly-formed virions non-infectious. To our knowledge, GSK232 has not been tested against HIV-2, and there are limited data regarding the susceptibility of HIV-2 to other HIV-1 maturation inhibitors. To assess the potential utility of GSK232 as an option for HIV-2 treatment, we determined the activity of the compound against a panel of HIV-1, HIV-2, and SIV isolates in culture. GSK232 was highly active against HIV-1 isolates from group M subtypes A, B, C, D, F, and group O, with IC50 values ranging from 0.25-0.92 nM in spreading (multi-cycle) assays and 1.5-2.8 nM in a single cycle of infection. In contrast, HIV-2 isolates from groups A, B, and CRF01_AB, and SIV isolates SIVmac239, SIVmac251, and SIVagm.sab-2, were highly resistant to GSK232. To determine the role of CA/SP1 in the observed phenotypes, we constructed a mutant of HIV-2ROD9 in which the sequence of CA/SP1 was modified to match the corresponding sequence found in HIV-1. The resulting variant was fully susceptible to GSK232 in the single-cycle assay (IC50 = 1.8 nM). Collectively, our data indicate that the HIV-2 and SIV isolates tested in our study are intrinsically resistant to GSK232, and that the determinants of resistance map to CA/SP1. The molecular mechanism(s) responsible for the differential susceptibility of HIV-1 and HIV-2/SIV to GSK232 require further investigation.
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Affiliation(s)
- Robert A. Smith
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Dana N. Raugi
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Robert S. Nixon
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Jennifer Song
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Moussa Seydi
- Service des Maladies Infectieuses et Tropicales, CHNU de Fann, Dakar, Senegal
| | - Geoffrey S. Gottlieb
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
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7
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Hartz RA, Xu L, Sit SY, Chen J, Venables BL, Lin Z, Zhang S, Li Z, Parker D, Simmons TS, Jenkins S, Hanumegowda UM, Dicker I, Krystal M, Meanwell NA, Regueiro-Ren A. Synthesis, Structure-Activity Relationships, and In Vivo Evaluation of Novel C-17 Amine Derivatives Based on GSK3640254 as HIV-1 Maturation Inhibitors with Broad Spectrum Activity. J Med Chem 2022; 65:15935-15966. [PMID: 36441509 DOI: 10.1021/acs.jmedchem.2c01618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An investigation of the structure-activity relationships of a series of HIV-1 maturation inhibitors (MIs) based on GSK3640254 (4) was conducted by incorporating novel C-17 amine substituents to reduce the overall basicity of the resultant analogues. We found that replacement of the distal amine on the C-17 sidechain present in 4 with a tertiary alcohol in combination with either a heterocyclic ring system or a cyclohexyl ring substituted with polar groups provided potent wild-type HIV-1 MIs that also retained excellent potency against a T332S/V362I/prR41G variant, a laboratory strain that served as a surrogate to assess HIV-1 polymorphic virus coverage. Compound 26 exhibited broad-spectrum HIV-1 activity against an expanded panel of clinically relevant Gag polymorphic viruses and had the most desirable overall profile in this series of compounds. In pharmacokinetic studies, 26 had low clearance and exhibited 24 and 31% oral bioavailability in rats and dogs, respectively.
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Affiliation(s)
- Richard A Hartz
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Li Xu
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Sing-Yuen Sit
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Jie Chen
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Brian L Venables
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Zeyu Lin
- Department of Virology, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Sharon Zhang
- Department of Virology, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Zhufang Li
- Department of Virology, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Dawn Parker
- Department of Metabolism and Pharmacokinetics, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Tara S Simmons
- Department of Metabolism and Pharmacokinetics, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Susan Jenkins
- Department of Metabolism and Pharmacokinetics, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Umesh M Hanumegowda
- Department of Metabolism and Pharmacokinetics, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Ira Dicker
- Department of Virology, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Mark Krystal
- Department of Virology, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Nicholas A Meanwell
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Alicia Regueiro-Ren
- Department of Small Molecule Drug Discovery, Bristol Myers Squibb, Research and Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
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8
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Targeting the Virus Capsid as a Tool to Fight RNA Viruses. Viruses 2022; 14:v14020174. [PMID: 35215767 PMCID: PMC8879806 DOI: 10.3390/v14020174] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 12/10/2022] Open
Abstract
Several strategies have been developed to fight viral infections, not only in humans but also in animals and plants. Some of them are based on the development of efficient vaccines, to target the virus by developed antibodies, others focus on finding antiviral compounds with activities that inhibit selected virus replication steps. Currently, there is an increasing number of antiviral drugs on the market; however, some have unpleasant side effects, are toxic to cells, or the viruses quickly develop resistance to them. As the current situation shows, the combination of multiple antiviral strategies or the combination of the use of various compounds within one strategy is very important. The most desirable are combinations of drugs that inhibit different steps in the virus life cycle. This is an important issue especially for RNA viruses, which replicate their genomes using error-prone RNA polymerases and rapidly develop mutants resistant to applied antiviral compounds. Here, we focus on compounds targeting viral structural capsid proteins, thereby inhibiting virus assembly or disassembly, virus binding to cellular receptors, or acting by inhibiting other virus replication mechanisms. This review is an update of existing papers on a similar topic, by focusing on the most recent advances in the rapidly evolving research of compounds targeting capsid proteins of RNA viruses.
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9
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Krebs AS, Mendonça LM, Zhang P. Structural Analysis of Retrovirus Assembly and Maturation. Viruses 2021; 14:54. [PMID: 35062258 PMCID: PMC8778513 DOI: 10.3390/v14010054] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
Abstract
Retroviruses have a very complex and tightly controlled life cycle which has been studied intensely for decades. After a virus enters the cell, it reverse-transcribes its genome, which is then integrated into the host genome, and subsequently all structural and regulatory proteins are transcribed and translated. The proteins, along with the viral genome, assemble into a new virion, which buds off the host cell and matures into a newly infectious virion. If any one of these steps are faulty, the virus cannot produce infectious viral progeny. Recent advances in structural and molecular techniques have made it possible to better understand this class of viruses, including details about how they regulate and coordinate the different steps of the virus life cycle. In this review we summarize the molecular analysis of the assembly and maturation steps of the life cycle by providing an overview on structural and biochemical studies to understand these processes. We also outline the differences between various retrovirus families with regards to these processes.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Luiza M. Mendonça
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, UK
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10
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Stephan Oroszlan and the Proteolytic Processing of Retroviral Proteins: Following A Pro. Viruses 2021; 13:v13112218. [PMID: 34835024 PMCID: PMC8621278 DOI: 10.3390/v13112218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 12/26/2022] Open
Abstract
Steve Oroszlan determined the sequences at the ends of virion proteins for a number of different retroviruses. This work led to the insight that the amino-terminal amino acid of the mature viral CA protein is always proline. In this remembrance, we review Steve’s work that led to this insight and show how that insight was a necessary precursor to the work we have done in the subsequent years exploring the cleavage rate determinants of viral protease processing sites and the multiple roles the amino-terminal proline of CA plays after protease cleavage liberates it from its position in a protease processing site.
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11
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Poston D, Zang T, Bieniasz P. Derivation and characterization of an HIV-1 mutant that rescues IP 6 binding deficiency. Retrovirology 2021; 18:25. [PMID: 34454514 PMCID: PMC8403458 DOI: 10.1186/s12977-021-00571-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 08/19/2021] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND A critical step in the HIV-1 replication cycle is the assembly of Gag proteins to form virions at the plasma membrane. Virion assembly and maturation are facilitated by the cellular polyanion inositol hexaphosphate (IP6), which is proposed to stabilize both the immature Gag lattice and the mature capsid lattice by binding to rings of primary amines at the center of Gag or capsid protein (CA) hexamers. The amino acids comprising these rings are critical for proper virion formation and their substitution results in assembly deficits or impaired infectiousness. To better understand the nature of the deficits that accompany IP6 binding deficiency, we passaged HIV-1 mutants that had substitutions in IP6 coordinating residues to select for compensatory mutations. RESULTS We found a mutation, a threonine to isoleucine substitution at position 371 (T371I) in Gag, that restored replication competence to an IP6-binding-deficient HIV-1 mutant. Notably, unlike wild-type HIV-1, the assembly and infectiousness of resulting virus was not impaired when IP6 biosynthetic enzymes were genetically ablated. Surprisingly, we also found that the maturation inhibitor Bevirimat (BVM) could restore the assembly and replication of an IP6-binding deficient mutant. Moreover, using BVM-dependent mutants we were able to image BVM-induced assembly of individual HIV-1 particles assembly in living cells. CONCLUSIONS Overall these results suggest that IP6-Gag and Gag-Gag contacts are finely tuned to generate a Gag lattice of optimal stability, and that under certain conditions BVM can rescue IP6 deficiency. Additionally, our work identifies an inducible virion assembly system that can be utilized to visualize HIV-1 assembly events using live cell microscopy.
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Affiliation(s)
- Daniel Poston
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
- Weill Cornell/Rockefeller/Sloan-Kettering Tri-Institutional MD-PhD Program, New York, NY, USA
| | - Trinity Zang
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA
- Howard Hughes Medical Institute, New York, NY, USA
| | - Paul Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, USA.
- Howard Hughes Medical Institute, New York, NY, USA.
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12
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Rose KM. When in Need of an ESCRT: The Nature of Virus Assembly Sites Suggests Mechanistic Parallels between Nuclear Virus Egress and Retroviral Budding. Viruses 2021; 13:v13061138. [PMID: 34199191 PMCID: PMC8231873 DOI: 10.3390/v13061138] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/01/2021] [Accepted: 06/02/2021] [Indexed: 12/17/2022] Open
Abstract
The proper assembly and dissemination of progeny virions is a fundamental step in virus replication. As a whole, viruses have evolved a myriad of strategies to exploit cellular compartments and mechanisms to ensure a successful round of infection. For enveloped viruses such as retroviruses and herpesviruses, acquisition and incorporation of cellular membrane is an essential process during the formation of infectious viral particles. To do this, these viruses have evolved to hijack the host Endosomal Sorting Complexes Required for Transport (ESCRT-I, -II, and -III) to coordinate the sculpting of cellular membrane at virus assembly and dissemination sites, in seemingly different, yet fundamentally similar ways. For instance, at the plasma membrane, ESCRT-I recruitment is essential for HIV-1 assembly and budding, while it is dispensable for the release of HSV-1. Further, HSV-1 was shown to recruit ESCRT-III for nuclear particle assembly and egress, a process not used by retroviruses during replication. Although the cooption of ESCRTs occurs in two separate subcellular compartments and at two distinct steps for these viral lifecycles, the role fulfilled by ESCRTs at these sites appears to be conserved. This review discusses recent findings that shed some light on the potential parallels between retroviral budding and nuclear egress and proposes a model where HSV-1 nuclear egress may occur through an ESCRT-dependent mechanism.
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Affiliation(s)
- Kevin M Rose
- Department of Molecular and Cell Biology, California Institute for Quantitative Biosciences, University of California-Berkeley, Berkeley, CA 94720, USA
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13
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Ghimire D, Kc Y, Timilsina U, Goel K, Nitz TJ, Wild CT, Gaur R. A single G10T polymorphism in HIV-1 subtype C Gag-SP1 regulates sensitivity to maturation inhibitors. Retrovirology 2021; 18:9. [PMID: 33836787 PMCID: PMC8033686 DOI: 10.1186/s12977-021-00553-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/23/2021] [Indexed: 08/30/2023] Open
Abstract
BACKGROUND Maturation inhibitors (MIs) potently block HIV-1 maturation by inhibiting the cleavage of the capsid protein and spacer peptide 1 (CA-SP1). Bevirimat (BVM), a highly efficacious first-in-class MI against HIV-1 subtype B isolates, elicited sub-optimal efficacy in clinical trials due to polymorphisms in the CA-SP1 region of the Gag protein (SP1:V7A). HIV-1 subtype C inherently contains this polymorphism thus conferring BVM resistance, however it displayed sensitivity to second generation BVM analogs. RESULTS In this study, we have assessed the efficacy of three novel second-generation MIs (BVM analogs: CV-8611, CV-8612, CV-8613) against HIV-1 subtype B and C isolates. The BVM analogs were potent inhibitors of both HIV-1 subtype B (NL4-3) and subtype C (K3016) viruses. Serial passaging of the subtype C, K3016 virus strain in the presence of BVM analogs led to identification of two mutant viruses-Gag SP1:A1V and CA:I201V. While the SP1:A1V mutant was resistant to the MIs, the CA:I120V mutant displayed partial resistance and a MI-dependent phenotype. Further analysis of the activity of the BVM analogs against two additional HIV-1 subtype C strains, IndieC1 and ZM247 revealed that they had reduced sensitivity as compared to K3016. Sequence analysis of the three viruses identified two polymorphisms at SP1 residues 9 and 10 (K3016: N9, G10; IndieC1/ZM247: S9, T10). The N9S and S9N mutants had no change in MI-sensitivity. On the other hand, replacing glycine at residue 10 with threonine in K3016 reduced its MI sensitivity whereas introducing glycine at SP1 10 in place of threonine in IndieC1 and ZM247 significantly enhanced their MI sensitivity. Thus, the specific glycine residue 10 of SP1 in the HIV-1 subtype C viruses determined sensitivity towards BVM analogs. CONCLUSIONS We have identified an association of a specific glycine at position 10 of Gag-SP1 with an MI susceptible phenotype of HIV-1 subtype C viruses. Our findings have highlighted that HIV-1 subtype C viruses, which were inherently resistant to BVM, may also be similarly predisposed to exhibit a significant degree of resistance to second-generation BVM analogs. Our work has strongly suggested that genetic differences between HIV-1 subtypes may produce variable MI sensitivity that needs to be considered in the development of novel, potent, broadly-active MIs.
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Affiliation(s)
- Dibya Ghimire
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, 110021, India
| | - Yuvraj Kc
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, 110021, India
| | - Uddhav Timilsina
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, 110021, India.,Department of Microbiology and Immunology, University at Buffalo, Buffalo, NY, 14203, USA
| | - Kriti Goel
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, 110021, India
| | - T J Nitz
- DFH Pharma, Gaithersburg, MD, 20886, USA
| | | | - Ritu Gaur
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, 110021, India.
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14
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Mallery DL, Kleinpeter AB, Renner N, Faysal KMR, Novikova M, Kiss L, Wilson MSC, Ahsan B, Ke Z, Briggs JAG, Saiardi A, Böcking T, Freed EO, James LC. A stable immature lattice packages IP 6 for HIV capsid maturation. SCIENCE ADVANCES 2021; 7:7/11/eabe4716. [PMID: 33692109 PMCID: PMC7946374 DOI: 10.1126/sciadv.abe4716] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 01/21/2021] [Indexed: 05/05/2023]
Abstract
HIV virion assembly begins with the construction of an immature lattice consisting of Gag hexamers. Upon virion release, protease-mediated Gag cleavage leads to a maturation event in which the immature lattice disassembles and the mature capsid assembles. The cellular metabolite inositiol hexakisphosphate (IP6) and maturation inhibitors (MIs) both bind and stabilize immature Gag hexamers, but whereas IP6 promotes virus maturation, MIs inhibit it. Here we show that HIV is evolutionarily constrained to maintain an immature lattice stability that ensures IP6 packaging without preventing maturation. Replication-deficient mutant viruses with reduced IP6 recruitment display increased infectivity upon treatment with the MI PF46396 (PF96) or the acquisition of second-site compensatory mutations. Both PF96 and second-site mutations stabilise the immature lattice and restore IP6 incorporation, suggesting that immature lattice stability and IP6 binding are interdependent. This IP6 dependence suggests that modifying MIs to compete with IP6 for Gag hexamer binding could substantially improve MI antiviral potency.
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Affiliation(s)
- Donna L Mallery
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Alex B Kleinpeter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Nadine Renner
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - K M Rifat Faysal
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Mariia Novikova
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Leo Kiss
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Miranda S C Wilson
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Bilal Ahsan
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Zunlong Ke
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - John A G Briggs
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Adolfo Saiardi
- MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702-1201, USA.
| | - Leo C James
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK.
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15
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Heymann JB. High resolution electron tomography and segmentation-by-modeling interpretation in Bsoft. Protein Sci 2021; 30:44-59. [PMID: 32852078 PMCID: PMC7737767 DOI: 10.1002/pro.3938] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 11/11/2022]
Abstract
Bsoft offers many tools for the processing of tomographic tilt series and the interpretation of tomograms. Since I introduced tomography into Bsoft almost two decades ago, the field has advanced significantly, requiring refinement of old algorithms and development of new ones. The current direct detectors allow us to collect data more efficiently and with better quality, progressing towards automation. The goal is then to also automate alignment of tilt series and reconstruction. I added an estimation of the specimen thickness as well as fiducialless alignment, to augment the existing fiducial-based alignment. High-resolution work requires correction for the contrast transfer function, in tomography complicated by the tilted specimen. For this, I developed a method to generate a power spectrum using the whole micrograph, compensating for tilting. This is followed by routine determination of the contrast transfer function, and correction for it during reconstruction. The next steps involve interpretation of the tomogram, either by subtomogram averaging where possible, or by segmentation and modeling otherwise. Such interpretation actually constitutes the main time-consuming part of tomography and is less amenable to automation compared to the initial reconstruction.
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Affiliation(s)
- J. Bernard Heymann
- Laboratory for Structural Biology ResearchNational Institute of Arthritis, Musculoskeletal and Skin Diseases, NIHBethesdaMarylandUSA
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16
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Chen X, Coric P, Larue V, Turcaud S, Wang X, Nonin-Lecomte S, Bouaziz S. The HIV-1 maturation inhibitor, EP39, interferes with the dynamic helix-coil equilibrium of the CA-SP1 junction of Gag. Eur J Med Chem 2020; 204:112634. [PMID: 32717487 DOI: 10.1016/j.ejmech.2020.112634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 06/29/2020] [Accepted: 06/29/2020] [Indexed: 11/30/2022]
Abstract
During the maturation of HIV-1 particle, the Gag polyprotein is cleaved into several proteins by the HIV-1 protease. These proteins rearrange to form infectious virus particles. In this study, the solution structure and dynamics of a monomeric mutated domain encompassing the C-terminal of capsid, the spacer peptide SP1 and the nucleocapsid from Gag was characterized by Nuclear Magnetic Resonance in the presence of maturation inhibitor EP39, a more hydro-soluble derivative of BVM. We show that the binding of EP39 decreases the dynamics of CA-SP1 junction, especially the QVT motif in SP1, and perturbs the natural coil-helix equilibrium on both sides of the SP1 domain by stabilizing the transient alpha helical structure. Our results provide new insight into the structure and dynamics of the SP1 domain and how HIV-1 maturation inhibitors interfere with this domain. They offer additional clues for the development of new second generation inhibitors targeting HIV-1 maturation.
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Affiliation(s)
- Xiaowei Chen
- CiTCoM, CNRS, UMR 8038, Université de Paris, 4 Avenue de L'Observatoire, Paris, 75270, France
| | - Pascale Coric
- CiTCoM, CNRS, UMR 8038, Université de Paris, 4 Avenue de L'Observatoire, Paris, 75270, France
| | - Valery Larue
- CiTCoM, CNRS, UMR 8038, Université de Paris, 4 Avenue de L'Observatoire, Paris, 75270, France
| | - Serge Turcaud
- LCBPT, CNRS, UMR 8601, Université de Paris, Paris, 45 Rue des Saints Pères, 75270, France
| | - Xiao Wang
- CiTCoM, CNRS, UMR 8038, Université de Paris, 4 Avenue de L'Observatoire, Paris, 75270, France
| | - Sylvie Nonin-Lecomte
- CiTCoM, CNRS, UMR 8038, Université de Paris, 4 Avenue de L'Observatoire, Paris, 75270, France
| | - Serge Bouaziz
- CiTCoM, CNRS, UMR 8038, Université de Paris, 4 Avenue de L'Observatoire, Paris, 75270, France.
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17
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Kleinpeter AB, Freed EO. HIV-1 Maturation: Lessons Learned from Inhibitors. Viruses 2020; 12:E940. [PMID: 32858867 PMCID: PMC7552077 DOI: 10.3390/v12090940] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 02/06/2023] Open
Abstract
Since the emergence of HIV and AIDS in the early 1980s, the development of safe and effective therapies has accompanied a massive increase in our understanding of the fundamental processes that drive HIV biology. As basic HIV research has informed the development of novel therapies, HIV inhibitors have been used as probes for investigating basic mechanisms of HIV-1 replication, transmission, and pathogenesis. This positive feedback cycle has led to the development of highly effective combination antiretroviral therapy (cART), which has helped stall the progression to AIDS, prolong lives, and reduce transmission of the virus. However, to combat the growing rates of virologic failure and toxicity associated with long-term therapy, it is important to diversify our repertoire of HIV-1 treatments by identifying compounds that block additional steps not targeted by current drugs. Most of the available therapeutics disrupt early events in the replication cycle, with the exception of the protease (PR) inhibitors, which act at the virus maturation step. HIV-1 maturation consists of a series of biochemical changes that facilitate the conversion of an immature, noninfectious particle to a mature infectious virion. These changes include proteolytic processing of the Gag polyprotein by the viral protease (PR), structural rearrangement of the capsid (CA) protein, and assembly of individual CA monomers into hexamers and pentamers that ultimately form the capsid. Here, we review the development and therapeutic potential of maturation inhibitors (MIs), an experimental class of anti-HIV-1 compounds with mechanisms of action distinct from those of the PR inhibitors. We emphasize the key insights into HIV-1 biology and structure that the study of MIs has provided. We will focus on three distinct groups of inhibitors that block HIV-1 maturation: (1) compounds that block the processing of the CA-spacer peptide 1 (SP1) cleavage intermediate, the original class of compounds to which the term MI was applied; (2) CA-binding inhibitors that disrupt capsid condensation; and (3) allosteric integrase inhibitors (ALLINIs) that block the packaging of the viral RNA genome into the condensing capsid during maturation. Although these three classes of compounds have distinct structures and mechanisms of action, they share the ability to block the formation of the condensed conical capsid, thereby blocking particle infectivity.
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Affiliation(s)
| | - Eric O. Freed
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA;
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18
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Schlicksup CJ, Zlotnick A. Viral structural proteins as targets for antivirals. Curr Opin Virol 2020; 45:43-50. [PMID: 32777753 DOI: 10.1016/j.coviro.2020.07.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 12/29/2022]
Abstract
Viral structural proteins are emerging as effective targets for new antivirals. In a viral lifecycle, the capsid must assemble, disassemble, and respond to host proteins, all at the right time and place. These reactions work within a narrow range of conditions, making them susceptible to small molecule interference. In at least three specific viruses, this approach has had met with preliminary success. In rhinovirus and poliovirus, compounds like pleconaril bind capsid and block RNA release. Bevirimat binds to Gag protein in HIV, inhibiting maturation. In Hepatitis B virus, core protein allosteric modulators (CpAMs) promote spontaneous assembly of capsid protein leading to empty and aberrant particles. Despite the biological diversity between viruses and the chemical diversity between antiviral molecules, we observe common features in these antivirals' mechanisms of action. These approaches work by stabilizing protein-protein interactions.
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Affiliation(s)
- Christopher John Schlicksup
- Molecular and Cellular Biology Department, Indiana University-Bloomington, Bloomington, IN 47401, United States
| | - Adam Zlotnick
- Molecular and Cellular Biology Department, Indiana University-Bloomington, Bloomington, IN 47401, United States.
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19
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Effects of an HIV-1 maturation inhibitor on the structure and dynamics of CA-SP1 junction helices in virus-like particles. Proc Natl Acad Sci U S A 2020; 117:10286-10293. [PMID: 32341150 DOI: 10.1073/pnas.1917755117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
HIV-1 maturation involves conversion of the immature Gag polyprotein lattice, which lines the inner surface of the viral membrane, to the mature capsid protein (CA) lattice, which encloses the viral RNA. Maturation inhibitors such as bevirimat (BVM) bind within six-helix bundles, formed by a segment that spans the junction between the CA and spacer peptide 1 (SP1) subunits of Gag, and interfere with cleavage between CA and SP1 catalyzed by the HIV-1 protease (PR). We report solid-state NMR (ssNMR) measurements on spherical virus-like particles (VLPs), facilitated by segmental isotopic labeling, that provide information about effects of BVM on the structure and dynamics of CA-SP1 junction helices in the immature lattice. Although BVM strongly blocks PR-catalyzed CA-SP1 cleavage in VLPs and blocks conversion of VLPs to tubular CA assemblies, 15N and 13C ssNMR chemical shifts of segmentally labeled VLPs with and without BVM are very similar, indicating that interaction with BVM does not alter the six-helix bundle structure appreciably. Only the 15N chemical shift of A280 (the first residue of SP1) changes significantly, consistent with BVM binding to an internal ring of hydrophobic side chains of L279 residues. Measurements of transverse 15N spin relaxation rates reveal a reduction in the amplitudes and/or timescales of backbone N-H bond motions, corresponding to a rigidification of the six-helix bundles. Overall, our data show that inhibition of HIV-1 maturation by BVM involves changes in structure and dynamics that are surprisingly subtle, but still sufficient to produce a large effect on CA-SP1 cleavage.
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20
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Anderson-Daniels J, Singh PK, Sowd GA, Li W, Engelman AN, Aiken C. Dominant Negative MA-CA Fusion Protein Is Incorporated into HIV-1 Cores and Inhibits Nuclear Entry of Viral Preintegration Complexes. J Virol 2019; 93:e01118-19. [PMID: 31413124 PMCID: PMC6803256 DOI: 10.1128/jvi.01118-19] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 08/03/2019] [Indexed: 11/20/2022] Open
Abstract
Particle maturation is a critical step in the HIV-1 replication cycle that requires proteolytic cleavage of the Gag polyprotein into its constitutive proteins: the matrix (MA), capsid (CA), nucleocapsid (NC), and p6 proteins. The accurate and efficient cleavage of Gag is essential for virion infectivity; inhibitors of the viral protease are potent antivirals, and substitutions in Gag that prevent its cleavage result in reduced HIV-1 infectivity. In a previous study, a mutation inhibiting cleavage at the MA-CA junction was observed to potently inhibit virus infection: incorporation of small amounts of uncleaved MA-CA protein into HIV-1 particles inhibited infectivity by ∼95%, and the resulting viral particles exhibited aberrant capsids. Here we report a detailed mechanistic analysis of HIV-1 particles bearing uncleaved MA-CA protein. We show that the particles contain stable cores and can efficiently saturate host restriction by TRIMCyp in target cells. We further show that MA-CA associates with CA in particles without detectably affecting the formation of intermolecular CA interfaces. Incorporation of MA-CA did not markedly affect reverse transcription in infected cells, but nuclear entry was impaired and integration targeting was altered. Additionally, results from mutational analysis of Gag revealed that membrane-binding elements of MA contribute to the antiviral activity of uncleaved MA-CA protein. Our results suggest that small amounts of partially processed Gag subunits coassemble with CA during virion maturation, resulting in impaired capsid functions.IMPORTANCE To become infectious, newly formed HIV-1 particles undergo a process of maturation in which the viral polyproteins are cleaved into smaller components. A previous study demonstrated that inclusion of even small quantities of an uncleavable mutant Gag polyprotein results in a strong reduction in virus infectivity. Here we show that the mechanism of transdominant inhibition by uncleavable Gag involves inhibition of nuclear entry and alteration of viral integration sites. Additionally, the results of mutational analysis suggest that the membrane-binding activity of Gag is a major requirement for the antiviral activity. These results further define the antiviral mechanism of uncleavable Gag, which may be useful for exploiting this effect to develop new antivirals.
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Affiliation(s)
- Jordan Anderson-Daniels
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Parmit K Singh
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Gregory A Sowd
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Wen Li
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
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21
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Dicker I, Zhang S, Ray N, Beno BR, Regueiro-Ren A, Joshi S, Cockett M, Krystal M, Lataillade M. Resistance profile of the HIV-1 maturation inhibitor GSK3532795 in vitro and in a clinical study. PLoS One 2019; 14:e0224076. [PMID: 31622432 PMCID: PMC6797179 DOI: 10.1371/journal.pone.0224076] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Accepted: 10/05/2019] [Indexed: 12/11/2022] Open
Abstract
GSK3532795 (formerly BMS955176) is a second-generation maturation inhibitor (MI) that progressed through a Phase 2b study for treatment of HIV-1 infection. Resistance development to GSK3532795 was evaluated through in vitro methods and was correlated with information obtained in a Phase 2a proof-of-concept study in HIV-1 infected participants. Both low and high concentrations of GSK3532795 were used for selections in vitro, and reduced susceptibility to GSK3532795 mapped specifically to amino acids near the capsid/ spacer peptide 1 (SP1) junction, the cleavage of which is blocked by MIs. Two key substitutions, A364V or V362I, were selected, the latter requiring secondary substitutions to reduce susceptibility to GSK3532795. Three main types of secondary substitutions were observed, none of which reduced GSK3532795 susceptibility in isolation. The first type was in the capsid C-terminal domain and downstream SP1 region (including (Gag numbering) R286K, A326T, T332S/N, I333V and V370A/M). The second, was an R41G substitution in viral protease that occurred with V362I. The third was seen in the capsid N-terminal domain, within the cyclophilin A binding domain (V218A/M, H219Q and G221E). H219Q increased viral replication capacity and reduced susceptibility of poorly growing viruses. In the Phase 2a study, a subset of these substitutions was also observed at baseline and some were selected following GSK35323795 treatment in HIV-1-infected participants.
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Affiliation(s)
- Ira Dicker
- Department of HIV Discovery, ViiV Healthcare, Branford, Connecticut, United States of America
| | - Sharon Zhang
- Department of HIV Discovery, ViiV Healthcare, Branford, Connecticut, United States of America
| | - Neelanjana Ray
- Department of Early Development, Bristol-Myers Squibb Research and Development, Princeton, New Jersey, United States of America
| | - Brett R. Beno
- Department of Molecular Discovery Technologies, Bristol-Myers Squibb Research and Development, Wallingford, Connecticut, United States of America
| | - Alicia Regueiro-Ren
- Department of Chemistry Bristol-Myers Squibb Research and Development, Wallingford Connecticut, United States of America
| | - Samit Joshi
- Department of Early Development, ViiV Healthcare, Branford, Connecticut, United States of America
| | - Mark Cockett
- Department of HIV Discovery, ViiV Healthcare, Branford, Connecticut, United States of America
| | - Mark Krystal
- Department of HIV Discovery, ViiV Healthcare, Branford, Connecticut, United States of America
| | - Max Lataillade
- Department of Early Development, ViiV Healthcare, Branford, Connecticut, United States of America
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22
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Recent Achievements in Medicinal and Supramolecular Chemistry of Betulinic Acid and Its Derivatives ‡. Molecules 2019; 24:molecules24193546. [PMID: 31574991 PMCID: PMC6803882 DOI: 10.3390/molecules24193546] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 09/27/2019] [Accepted: 09/29/2019] [Indexed: 01/02/2023] Open
Abstract
The subject of this review article refers to the recent achievements in the investigation of pharmacological activity and supramolecular characteristics of betulinic acid and its diverse derivatives, with special focus on their cytotoxic effect, antitumor activity, and antiviral effect, and mostly covers a period 2015–2018. Literature sources published earlier are referred to in required coherences or from historical points of view. Relationships between pharmacological activity and supramolecular characteristics are included if such investigation has been done in the original literature sources. A wide practical applicability of betulinic acid and its derivatives demonstrated in the literature sources is also included in this review article. Several literature sources also focused on in silico calculation of physicochemical and ADME parameters of the developed compounds, and on a comparison between the experimental and calculated data.
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Su CTT, Koh DWS, Gan SKE. Reviewing HIV-1 Gag Mutations in Protease Inhibitors Resistance: Insights for Possible Novel Gag Inhibitor Designs. Molecules 2019; 24:molecules24183243. [PMID: 31489889 PMCID: PMC6767625 DOI: 10.3390/molecules24183243] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 09/03/2019] [Accepted: 09/04/2019] [Indexed: 12/31/2022] Open
Abstract
HIV protease inhibitors against the viral protease are often hampered by drug resistance mutations in protease and in the viral substrate Gag. To overcome this drug resistance and inhibit viral maturation, targeting Gag alongside protease rather than targeting protease alone may be more efficient. In order to successfully inhibit Gag, understanding of its drug resistance mutations and the elicited structural changes on protease binding needs to be investigated. While mutations on Gag have already been mapped to protease inhibitor resistance, there remain many mutations, particularly the non-cleavage mutations, that are not characterized. Through structural studies to unravel how Gag mutations contributes to protease drug resistance synergistically, it is thus possible to glean insights to design novel Gag inhibitors. In this review, we discuss the structural role of both novel and previously reported Gag mutations in PI resistance, and how new Gag inhibitors can be designed.
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Affiliation(s)
- Chinh Tran-To Su
- Antibody & Product Development Lab, Bioinformatics Institute, A*STAR, Singapore 138671, Singapore
| | - Darius Wen-Shuo Koh
- Antibody & Product Development Lab, Bioinformatics Institute, A*STAR, Singapore 138671, Singapore
| | - Samuel Ken-En Gan
- Antibody & Product Development Lab, Bioinformatics Institute, A*STAR, Singapore 138671, Singapore.
- p53 Laboratory, A*STAR, Singapore 138648, Singapore.
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Obr M, Schur FKM. Structural analysis of pleomorphic and asymmetric viruses using cryo-electron tomography and subtomogram averaging. Adv Virus Res 2019; 105:117-159. [PMID: 31522703 DOI: 10.1016/bs.aivir.2019.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Describing the protein interactions that form pleomorphic and asymmetric viruses represents a considerable challenge to most structural biology techniques, including X-ray crystallography and single particle cryo-electron microscopy. Obtaining a detailed understanding of these interactions is nevertheless important, considering the number of relevant human pathogens that do not follow strict icosahedral or helical symmetry. Cryo-electron tomography and subtomogram averaging methods provide structural insights into complex biological environments and are well suited to go beyond structures of perfectly symmetric viruses. This chapter discusses recent developments showing that cryo-ET and subtomogram averaging can provide high-resolution insights into hitherto unknown structural features of pleomorphic and asymmetric virus particles. It also describes how these methods have significantly added to our understanding of retrovirus capsid assemblies in immature and mature viruses. Additional examples of irregular viruses and their associated proteins, whose structures have been studied via cryo-ET and subtomogram averaging, further support the versatility of these methods.
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Affiliation(s)
- Martin Obr
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Florian K M Schur
- Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria.
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25
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Pornillos O, Ganser-Pornillos BK. Maturation of retroviruses. Curr Opin Virol 2019; 36:47-55. [PMID: 31185449 PMCID: PMC6730672 DOI: 10.1016/j.coviro.2019.05.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/29/2019] [Accepted: 05/03/2019] [Indexed: 01/10/2023]
Abstract
During retrovirus maturation, cleavage of the precursor structural Gag polyprotein by the viral protease induces architectural rearrangement of the virus particle from an immature into a mature, infectious form. The structural rearrangement encapsidates the viral RNA genome in a fullerene capsid, producing a diffusible viral core that can initiate infection upon entry into the cytoplasm of a host cell. Maturation is an important therapeutic window against HIV-1. In this review, we highlight recent breakthroughs in understanding of the structures of retroviral immature and mature capsid lattices that define the boundary conditions of maturation and provide novel insights on capsid transformation. We also discuss emerging insights on encapsidation of the viral genome in the mature capsid, as well as remaining questions for further study.
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Affiliation(s)
- Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
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Novikova M, Zhang Y, Freed EO, Peng K. Multiple Roles of HIV-1 Capsid during the Virus Replication Cycle. Virol Sin 2019; 34:119-134. [PMID: 31028522 PMCID: PMC6513821 DOI: 10.1007/s12250-019-00095-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 01/16/2019] [Indexed: 11/29/2022] Open
Abstract
Human immunodeficiency virus-1 capsid (HIV-1 CA) is involved in different stages of the viral replication cycle. During virion assembly, CA drives the formation of the hexameric lattice in immature viral particles, while in mature virions CA monomers assemble in cone-shaped cores surrounding the viral RNA genome and associated proteins. In addition to its functions in late stages of the viral replication cycle, CA plays key roles in a number of processes during early phases of HIV-1 infection including trafficking, uncoating, recognition by host cellular proteins and nuclear import of the viral pre-integration complex. As a result of efficient cooperation of CA with other viral and cellular proteins, integration of the viral genetic material into the host genome, which is an essential step for productive viral infection, successfully occurs. In this review, we will summarize available data on CA functions in HIV-1 replication, describing in detail its roles in late and early phases of the viral replication cycle.
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Affiliation(s)
- Mariia Novikova
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Yulan Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Ke Peng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
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Urano E, Timilsina U, Kaplan JA, Ablan S, Ghimire D, Pham P, Kuruppu N, Mandt R, Durell SR, Nitz TJ, Martin DE, Wild CT, Gaur R, Freed EO. Resistance to Second-Generation HIV-1 Maturation Inhibitors. J Virol 2019; 93:e02017-18. [PMID: 30567982 PMCID: PMC6401422 DOI: 10.1128/jvi.02017-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 12/10/2018] [Indexed: 12/26/2022] Open
Abstract
A betulinic acid-based compound, bevirimat (BVM), inhibits HIV-1 maturation by blocking a late step in protease-mediated Gag processing: the cleavage of the capsid-spacer peptide 1 (CA-SP1) intermediate to mature CA. Previous studies showed that mutations conferring resistance to BVM cluster around the CA-SP1 cleavage site. Single amino acid polymorphisms in the SP1 region of Gag and the C terminus of CA reduced HIV-1 susceptibility to BVM, leading to the discontinuation of BVM's clinical development. We recently reported a series of "second-generation" BVM analogs that display markedly improved potency and breadth of activity relative to the parent molecule. Here, we demonstrate that viral clones bearing BVM resistance mutations near the C terminus of CA are potently inhibited by second-generation BVM analogs. We performed de novo selection experiments to identify mutations that confer resistance to these novel compounds. Selection experiments with subtype B HIV-1 identified an Ala-to-Val mutation at SP1 residue 1 and a Pro-to-Ala mutation at CA residue 157 within the major homology region (MHR). In selection experiments with subtype C HIV-1, we identified mutations at CA residue 230 (CA-V230M) and SP1 residue 1 (SP1-A1V), residue 5 (SP1-S5N), and residue 10 (SP1-G10R). The positions at which resistance mutations arose are highly conserved across multiple subtypes of HIV-1. We demonstrate that the mutations confer modest to high-level maturation inhibitor resistance. In most cases, resistance was not associated with a detectable increase in the kinetics of CA-SP1 processing. These results identify mutations that confer resistance to second-generation maturation inhibitors and provide novel insights into the mechanism of resistance.IMPORTANCE HIV-1 maturation inhibitors are a class of small-molecule compounds that block a late step in the viral protease-mediated processing of the Gag polyprotein precursor, the viral protein responsible for the formation of virus particles. The first-in-class HIV-1 maturation inhibitor bevirimat was highly effective in blocking HIV-1 replication, but its activity was compromised by naturally occurring sequence polymorphisms within Gag. Recently developed bevirimat analogs, referred to as "second-generation" maturation inhibitors, overcome this issue. To understand more about how these second-generation compounds block HIV-1 maturation, here we selected for HIV-1 mutants that are resistant to these compounds. Selections were performed in the context of two different subtypes of HIV-1. We identified a small set of mutations at highly conserved positions within the capsid and spacer peptide 1 domains of Gag that confer resistance. Identification and analysis of these maturation inhibitor-resistant mutants provide insights into the mechanisms of resistance to these compounds.
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Affiliation(s)
- Emiko Urano
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Uddhav Timilsina
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
| | - Justin A Kaplan
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Sherimay Ablan
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Dibya Ghimire
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
| | - Phuong Pham
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Nishani Kuruppu
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Rebecca Mandt
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
| | - Stewart R Durell
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, USA
| | | | | | | | - Ritu Gaur
- Faculty of Life Sciences and Biotechnology, South Asian University, New Delhi, India
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, Maryland, USA
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Insight into the mechanism of action of EP-39, a bevirimat derivative that inhibits HIV-1 maturation. Antiviral Res 2019; 164:162-175. [PMID: 30825471 DOI: 10.1016/j.antiviral.2019.02.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/19/2019] [Accepted: 02/22/2019] [Indexed: 12/15/2022]
Abstract
Maturation of human immunodeficiency virus type 1 (HIV-1) particles is a key step for viral infectivity. This process can be blocked using maturation inhibitors (MIs) that affect the cleavage of the capsid-spacer peptide 1 (CA-SP1) junction. Here, we investigated the mechanisms underlying the activity of EP-39, a bevirimat (BVM) derivative with better hydrosolubility. To this aim, we selected in vitro EP-39- and BVM-resistant mutants. We found that EP-39-resistant viruses have four mutations within the CA domain (CA-A194T, CA-T200N, CA-V230I, and CA-V230A) and one in the first residue of SP1 (SP1-A1V). We also identified six mutations that confer BVM resistance (CA-A194T, CA-L231F, CA-L231M, SP1-A1V, SP1-S5N and SP1-V7A). To characterize the EP-39 and BVM-resistant mutants, we studied EP-39 effects on mutant virus replication and performed a biochemical analysis with both MIs. We observed common and distinct characteristics, suggesting that, although EP-39 and BVM share the same chemical skeleton, they could interact in a different way with the Gag polyprotein precursor (Pr55Gag). Using an in silico approach, we observed that EP-39 and BVM present different predicted positions on the hexameric crystal structure of the CACTD-SP1 Gag fragment. To clearly understand the relationship between assembly and maturation, we investigated the impact of all identified mutations on virus assembly by expressing Pr55Gag mutants. Finally, using NMR, we have shown that the interaction of EP-39 with a peptide carrying the SP1-A1V mutation (CA-SP1(A1V)-NC) is almost suppressed in comparison with the wild type peptide. These results suggest that EP-39 and BVM could interact differently with the Pr55Gag lattice and that the mutation of the first SP1 residue induces a loss of interaction between Pr55Gag and EP-39.
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MicroED structures of HIV-1 Gag CTD-SP1 reveal binding interactions with the maturation inhibitor bevirimat. Proc Natl Acad Sci U S A 2018; 115:13258-13263. [PMID: 30530702 DOI: 10.1073/pnas.1806806115] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
HIV-1 protease (PR) cleavage of the Gag polyprotein triggers the assembly of mature, infectious particles. Final cleavage of Gag occurs at the junction helix between the capsid protein CA and the SP1 spacer peptide. Here we used MicroED to delineate the binding interactions of the maturation inhibitor bevirimat (BVM) using very thin frozen-hydrated, 3D microcrystals of a CTD-SP1 Gag construct with and without bound BVM. The 2.9-Å MicroED structure revealed that a single BVM molecule stabilizes the six-helix bundle via both electrostatic interactions with the dimethylsuccinyl moiety and hydrophobic interactions with the pentacyclic triterpenoid ring. These results provide insight into the mechanism of action of BVM and related maturation inhibitors that will inform further drug discovery efforts. This study also demonstrates the capabilities of MicroED for structure-based drug design.
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30
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Identification of a Structural Element in HIV-1 Gag Required for Virus Particle Assembly and Maturation. mBio 2018; 9:mBio.01567-18. [PMID: 30327442 PMCID: PMC6191540 DOI: 10.1128/mbio.01567-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Late in the HIV-1 replication cycle, the viral structural protein Gag is targeted to virus assembly sites at the plasma membrane of infected cells. The capsid (CA) domain of Gag plays a critical role in the formation of the hexameric Gag lattice in the immature virion, and, during particle release, CA is cleaved from the Gag precursor by the viral protease and forms the conical core of the mature virion. A highly conserved Pro-Pro-Ile-Pro (PPIP) motif (CA residues 122 to 125) [PPIP(122-125)] in a loop connecting CA helices 6 and 7 resides at a 3-fold axis formed by neighboring hexamers in the immature Gag lattice. In this study, we characterized the role of this PPIP(122-125) loop in HIV-1 assembly and maturation. While mutations P123A and P125A were relatively well tolerated, mutation of P122 and I124 significantly impaired virus release, caused Gag processing defects, and abolished infectivity. X-ray crystallography indicated that the P122A and I124A mutations induce subtle changes in the structure of the mature CA lattice which were permissive for in vitro assembly of CA tubes. Transmission electron microscopy and cryo-electron tomography demonstrated that the P122A and I124A mutations induce severe structural defects in the immature Gag lattice and abrogate conical core formation. Propagation of the P122A and I124A mutants in T-cell lines led to the selection of compensatory mutations within CA. Our findings demonstrate that the CA PPIP(122-125) loop comprises a structural element critical for the formation of the immature Gag lattice.IMPORTANCE Capsid (CA) plays multiple roles in the HIV-1 replication cycle. CA-CA domain interactions are responsible for multimerization of the Gag polyprotein at virus assembly sites, and in the mature virion, CA monomers assemble into a conical core that encapsidates the viral RNA genome. Multiple CA regions that contribute to the assembly and release of HIV-1 particles have been mapped and investigated. Here, we identified and characterized a Pro-rich loop in CA that is important for the formation of the immature Gag lattice. Changes in this region disrupt viral production and abrogate the formation of infectious, mature virions. Propagation of the mutants in culture led to the selection of second-site compensatory mutations within CA. These results expand our knowledge of the assembly and maturation steps in the viral replication cycle and may be relevant for development of antiviral drugs targeting CA.
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High-resolution structures of HIV-1 Gag cleavage mutants determine structural switch for virus maturation. Proc Natl Acad Sci U S A 2018; 115:E9401-E9410. [PMID: 30217893 PMCID: PMC6176557 DOI: 10.1073/pnas.1811237115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The main structural component of HIV-1 is the Gag polyprotein. During virus release, Gag is cleaved by the viral protease at five sites, triggering a major change in the structure and morphology of the virus. This transition, called maturation, is required to make an infectious virion. We used cryoelectron tomography to obtain high-resolution structures of Gag inside virus particles carrying mutations that block specific combinations of cleavage sites. Analysis of these structures suggests that different combinations of cleavages can destabilize a bundle of alpha-helices at the C terminus of CA. This destabilization, rather than formation of a beta-hairpin at the N terminus of CA as previously suggested, acts as the structural switch for maturation of the virus into its infectious form. HIV-1 maturation occurs via multiple proteolytic cleavages of the Gag polyprotein, causing rearrangement of the virus particle required for infectivity. Cleavage results in beta-hairpin formation at the N terminus of the CA (capsid) protein and loss of a six-helix bundle formed by the C terminus of CA and the neighboring SP1 peptide. How individual cleavages contribute to changes in protein structure and interactions, and how the mature, conical capsid forms, are poorly understood. Here, we employed cryoelectron tomography to determine morphology and high-resolution CA lattice structures for HIV-1 derivatives in which Gag cleavage sites are mutated. These analyses prompt us to revise current models for the crucial maturation switch. Unlike previously proposed, cleavage on either terminus of CA was sufficient, in principle, for lattice maturation, while complete processing was needed for conical capsid formation. We conclude that destabilization of the six-helix bundle, rather than beta-hairpin formation, represents the main determinant of structural maturation.
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Maturation inhibitors facilitate virus assembly and release of HIV-1 capsid P224 mutant. Virology 2018; 521:44-50. [DOI: 10.1016/j.virol.2018.05.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 05/28/2018] [Accepted: 05/29/2018] [Indexed: 01/25/2023]
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Dick RA, Zadrozny KK, Xu C, Schur FKM, Lyddon TD, Ricana CL, Wagner JM, Perilla JR, Ganser-Pornillos BK, Johnson MC, Pornillos O, Vogt VM. Inositol phosphates are assembly co-factors for HIV-1. Nature 2018; 560:509-512. [PMID: 30069050 PMCID: PMC6242333 DOI: 10.1038/s41586-018-0396-4] [Citation(s) in RCA: 169] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 07/10/2018] [Indexed: 01/02/2023]
Abstract
A short, 14-amino-acid segment called SP1, located in the Gag structural protein1, has a critical role during the formation of the HIV-1 virus particle. During virus assembly, the SP1 peptide and seven preceding residues fold into a six-helix bundle, which holds together the Gag hexamer and facilitates the formation of a curved immature hexagonal lattice underneath the viral membrane2,3. Upon completion of assembly and budding, proteolytic cleavage of Gag leads to virus maturation, in which the immature lattice is broken down; the liberated CA domain of Gag then re-assembles into the mature conical capsid that encloses the viral genome and associated enzymes. Folding and proteolysis of the six-helix bundle are crucial rate-limiting steps of both Gag assembly and disassembly, and the six-helix bundle is an established target of HIV-1 inhibitors4,5. Here, using a combination of structural and functional analyses, we show that inositol hexakisphosphate (InsP6, also known as IP6) facilitates the formation of the six-helix bundle and assembly of the immature HIV-1 Gag lattice. IP6 makes ionic contacts with two rings of lysine residues at the centre of the Gag hexamer. Proteolytic cleavage then unmasks an alternative binding site, where IP6 interaction promotes the assembly of the mature capsid lattice. These studies identify IP6 as a naturally occurring small molecule that promotes both assembly and maturation of HIV-1.
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Affiliation(s)
- Robert A Dick
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA.
| | - Kaneil K Zadrozny
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Chaoyi Xu
- Department of Chemistry and Biochemistry, University of Delaware, Newport, DE, USA
| | - Florian K M Schur
- Structural and Computational Biology Unit, EMBL, Heidelberg, Germany
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Terri D Lyddon
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, USA
| | - Clifton L Ricana
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, USA
| | - Jonathan M Wagner
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newport, DE, USA
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Marc C Johnson
- Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, USA
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
| | - Volker M Vogt
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
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The KT Jeang Retrovirology prize 2018: Eric Freed. Retrovirology 2018; 15:43. [PMID: 29966522 PMCID: PMC6027741 DOI: 10.1186/s12977-018-0430-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 06/26/2018] [Indexed: 11/10/2022] Open
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Cyrklaff M, Frischknecht F, Kudryashev M. Functional insights into pathogen biology from 3D electron microscopy. FEMS Microbiol Rev 2018; 41:828-853. [PMID: 28962014 DOI: 10.1093/femsre/fux041] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 07/25/2017] [Indexed: 01/10/2023] Open
Abstract
In recent years, novel imaging approaches revolutionised our understanding of the cellular and molecular biology of microorganisms. These include advances in fluorescent probes, dynamic live cell imaging, superresolution light and electron microscopy. Currently, a major transition in the experimental approach shifts electron microscopy studies from a complementary technique to a method of choice for structural and functional analysis. Here we review functional insights into the molecular architecture of viruses, bacteria and parasites as well as interactions with their respective host cells gained from studies using cryogenic electron tomography and related methodologies.
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Affiliation(s)
- Marek Cyrklaff
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Friedrich Frischknecht
- Integrative Parasitology, Center for Infectious Diseases, Heidelberg University Medical School, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Mikhail Kudryashev
- Max Planck Institute of Biophysics, Max-von-Laue Strasse 3, 60438 Frankfurt, Germany.,Buchmann Institute for Molecular Life Sciences, Goethe University of Frankfurt, Max-von-Laue Strasse 17, 60438 Frankfurt, Germany
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36
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Mak J, de Marco A. Recent advances in retroviruses via cryo-electron microscopy. Retrovirology 2018; 15:23. [PMID: 29471854 PMCID: PMC5824478 DOI: 10.1186/s12977-018-0405-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 02/14/2018] [Indexed: 12/14/2022] Open
Abstract
Cryo-electron microscopy has undergone a revolution in recent years and it has contributed significantly to a number of different areas in biological research. In this manuscript, we will describe some of the recent advancements in cryo-electron microscopy focussing on the advantages that this technique can bring rather than on the technology. We will then conclude discussing how the field of retrovirology has benefited from cryo-electron microscopy.
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Affiliation(s)
- Johnson Mak
- Institute for Glycomics, Griffith University Gold Coast, Southport, QLD, Australia
| | - Alex de Marco
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia.
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Che Nordin MA, Teow SY. Review of Current Cell-Penetrating Antibody Developments for HIV-1 Therapy. Molecules 2018; 23:molecules23020335. [PMID: 29415435 PMCID: PMC6017373 DOI: 10.3390/molecules23020335] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/06/2018] [Accepted: 01/08/2018] [Indexed: 12/22/2022] Open
Abstract
The discovery of highly active antiretroviral therapy (HAART) in 1996 has significantly reduced the global mortality and morbidity caused by the acquired immunodeficiency syndrome (AIDS). However, the therapeutic strategy of HAART that targets multiple viral proteins may render off-target toxicity and more importantly results in drug-resistant escape mutants. These have been the main challenges for HAART and refinement of this therapeutic strategy is urgently needed. Antibody-mediated treatments are emerging therapeutic modalities for various diseases. Most therapeutic antibodies have been approved by Food and Drug Administration (FDA) mainly for targeting cancers. Previous studies have also demonstrated the promising effect of therapeutic antibodies against HIV-1, but there are several limitations in this therapy, particularly when the viral targets are intracellular proteins. The conventional antibodies do not cross the cell membrane, hence, the pathogenic intracellular proteins cannot be targeted with this classical therapeutic approach. Over the years, the advancement of antibody engineering has permitted the therapeutic antibodies to comprehensively target both extra- and intra-cellular proteins in various infections and diseases. This review aims to update on the current progress in the development of antibody-based treatment against intracellular targets in HIV-1 infection. We also attempt to highlight the challenges and limitations in the development of antibody-based therapeutic modalities against HIV-1.
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Affiliation(s)
- Muhamad Alif Che Nordin
- Kulliyyah of Medicine and Health Sciences (KMHS), Kolej Universiti INSANIAH, 09300 Kuala Ketil, Kedah, Malaysia.
| | - Sin-Yeang Teow
- Sunway Institute for Healthcare Development (SIHD), School of Healthcare and Medical Sciences (SHMS), Sunway University, Jalan Universiti, Bandar Sunway, 47500 Subang Jaya, Selangor Darul Ehsan, Malaysia.
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38
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Wang M, Quinn CM, Perilla JR, Zhang H, Shirra R, Hou G, Byeon IJ, Suiter CL, Ablan S, Urano E, Nitz TJ, Aiken C, Freed EO, Zhang P, Schulten K, Gronenborn AM, Polenova T. Quenching protein dynamics interferes with HIV capsid maturation. Nat Commun 2017; 8:1779. [PMID: 29176596 PMCID: PMC5701193 DOI: 10.1038/s41467-017-01856-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 10/19/2017] [Indexed: 11/14/2022] Open
Abstract
Maturation of HIV-1 particles encompasses a complex morphological transformation of Gag via an orchestrated series of proteolytic cleavage events. A longstanding question concerns the structure of the C-terminal region of CA and the peptide SP1 (CA-SP1), which represents an intermediate during maturation of the HIV-1 virus. By integrating NMR, cryo-EM, and molecular dynamics simulations, we show that in CA-SP1 tubes assembled in vitro, which represent the features of an intermediate assembly state during maturation, the SP1 peptide exists in a dynamic helix-coil equilibrium, and that the addition of the maturation inhibitors Bevirimat and DFH-055 causes stabilization of a helical form of SP1. Moreover, the maturation-arresting SP1 mutation T8I also induces helical structure in SP1 and further global dynamical and conformational changes in CA. Overall, our results show that dynamics of CA and SP1 are critical for orderly HIV-1 maturation and that small molecules can inhibit maturation by perturbing molecular motions.
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Affiliation(s)
- Mingzhang Wang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
- University of Illinois, Theoretical and Computational Biophysics Group, Urbana, IL, 61801, USA.
| | - Huilan Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Randall Shirra
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - In-Ja Byeon
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Christopher L Suiter
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Sherimay Ablan
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Emiko Urano
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | | | - Christopher Aiken
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Eric O Freed
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Peijun Zhang
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, OX3 7BN, UK
| | - Klaus Schulten
- University of Illinois, Theoretical and Computational Biophysics Group, Urbana, IL, 61801, USA
| | - Angela M Gronenborn
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
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Monde K, Terasawa H, Nakano Y, Soheilian F, Nagashima K, Maeda Y, Ono A. Molecular mechanisms by which HERV-K Gag interferes with HIV-1 Gag assembly and particle infectivity. Retrovirology 2017; 14:27. [PMID: 28446240 PMCID: PMC5406883 DOI: 10.1186/s12977-017-0351-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 04/18/2017] [Indexed: 02/07/2023] Open
Abstract
Background Human endogenous retroviruses (HERVs), the remnants of ancient retroviral infections, constitute approximately 8% of human genomic DNA. Since HERV-K Gag expression is induced by HIV-1 Tat in T cells, induced HERV-K proteins could affect HIV-1 replication. Indeed, previously we showed that HERV-K Gag and HIV-1 Gag coassemble and that this appears to correlate with the effect of HERV-K Gag expression on HIV-1 particle release and its infectivity. We further showed that coassembly requires both MA and NC domains, which presumably serve as scaffolding for Gag via their abilities to bind membrane and RNA, respectively. Notably, however, despite possessing these abilities, MLV Gag failed to coassemble with HIV-1 Gag and did not affect assembly and infectivity of HIV-1 particles. It is unclear how the specificity of coassembly is determined. Results Here, we showed that coexpression of HERV-K Gag with HIV-1 Gag changed size and morphology of progeny HIV-1 particles and severely diminished infectivity of such progeny viruses. We further compared HERV-K-MLV chimeric constructs to identify molecular determinants for coassembly specificity and for inhibition of HIV-1 release efficiency and infectivity. We found that the CA N-terminal domain (NTD) of HERV-K Gag is important for the reduction of the HIV-1 release efficiency, whereas both CA-NTD and major homology region of HERV-K Gag contribute to colocalization with HIV-1 Gag. Interestingly, these regions of HERV-K Gag were not required for reduction of progeny HIV-1 infectivity. Conclusions Our results showed that HERV-K Gag CA is important for reduction of HIV-1 release and infectivity but the different regions within CA are involved in the effects on the HIV-1 release and infectivity. Altogether, these findings revealed that HERV-K Gag interferes the HIV-1 replication by two distinct molecular mechanisms. Electronic supplementary material The online version of this article (doi:10.1186/s12977-017-0351-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kazuaki Monde
- Department of Medical Virology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan. .,Department of Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.
| | - Hiromi Terasawa
- Department of Medical Virology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.,Department of Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Yusuke Nakano
- Department of Medical Virology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.,Laboratory of Viral Pathogenesis, Institute for Virus Research, Kyoto University, Kyoto, Japan
| | - Ferri Soheilian
- Electron Microscopy Laboratory, Leidos Biomedical Research, Inc, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Kunio Nagashima
- Electron Microscopy Laboratory, Leidos Biomedical Research, Inc, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Yosuke Maeda
- Department of Medical Virology, Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan.,Department of Microbiology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Akira Ono
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
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Inhibition of HIV-1 Maturation via Small-Molecule Targeting of the Amino-Terminal Domain in the Viral Capsid Protein. J Virol 2017; 91:JVI.02155-16. [PMID: 28202766 DOI: 10.1128/jvi.02155-16] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 02/09/2017] [Indexed: 11/20/2022] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) capsid protein is an attractive therapeutic target, owing to its multifunctionality in virus replication and the high fitness cost of amino acid substitutions in capsids to HIV-1 infectivity. To date, small-molecule inhibitors have been identified that inhibit HIV-1 capsid assembly and/or impair its function in target cells. Here, we describe the mechanism of action of the previously reported capsid-targeting HIV-1 inhibitor, Boehringer-Ingelheim compound 1 (C1). We show that C1 acts during HIV-1 maturation to prevent assembly of a mature viral capsid. However, unlike the maturation inhibitor bevirimat, C1 did not significantly affect the kinetics or fidelity of Gag processing. HIV-1 particles produced in the presence of C1 contained unstable capsids that lacked associated electron density and exhibited impairments in early postentry stages of infection, most notably reverse transcription. C1 inhibited assembly of recombinant HIV-1 CA in vitro and induced aberrant cross-links in mutant HIV-1 particles capable of spontaneous intersubunit disulfide bonds at the interhexamer interface in the capsid lattice. Resistance to C1 was conferred by a single amino acid substitution within the compound-binding site in the N-terminal domain of the CA protein. Our results demonstrate that the binding site for C1 represents a new pharmacological vulnerability in the capsid assembly stage of the HIV-1 life cycle.IMPORTANCE The HIV-1 capsid protein is an attractive but unexploited target for clinical drug development. Prior studies have identified HIV-1 capsid-targeting compounds that display different mechanisms of action, which in part reflects the requirement for capsid function at both the efferent and afferent phases of viral replication. Here, we show that one such compound, compound 1, interferes with assembly of the conical viral capsid during virion maturation and results in perturbations at a specific protein-protein interface in the capsid lattice. We also identify and characterize a mutation in the capsid protein that confers resistance to the inhibitor. This study reveals a novel mechanism by which a capsid-targeting small molecule can inhibit HIV-1 replication.
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41
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Insights into the activity of maturation inhibitor PF-46396 on HIV-1 clade C. Sci Rep 2017; 7:43711. [PMID: 28252110 PMCID: PMC5333120 DOI: 10.1038/srep43711] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 01/26/2017] [Indexed: 12/03/2022] Open
Abstract
HIV maturation inhibitors are an emerging class of anti-retroviral compounds that inhibit the viral protease-mediated cleavage of the Gag, CA-SP1 (capsid-spacer peptide 1) peptide to mature CA. The first-in-class maturation inhibitor bevirimat (BVM) displayed potent activity against HIV-1 clade B but was ineffective against other HIV-1 clades including clade C. Another pyridone-based maturation inhibitor, PF-46396 displayed potent activity against HIV-1 clade B. In this study, we aimed at determining the activity of PF-46396 against HIV-1 clade C. We employed various biochemical and virological assays to demonstrate that PF-46396 is effective against HIV-1 clade C. We observed a dose dependent accumulation of CA-SP1 intermediate in presence of the compound. We carried out mutagenesis in the CA- SP1 region of HIV-1 clade C Gag and observed that the mutations conferred resistance against the compound. Many mutations inhibited Gag processing thereby reducing virus release in the absence of the compound. However, presence of PF-46396 rescued these defects and enhanced virus release, replication capacity and infectivity of HIV-1 clade C. These results put together identify PF-46396 as a broadly active maturation inhibitor against HIV-1 clade B and C and help in rational designing of novel analogs with reduced toxicity and increased efficacy for its potential use in clinics.
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42
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Thenin-Houssier S, Valente ST. HIV-1 Capsid Inhibitors as Antiretroviral Agents. Curr HIV Res 2016; 14:270-82. [PMID: 26957201 DOI: 10.2174/1570162x14999160224103555] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 08/12/2015] [Accepted: 09/01/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND The infectious human immunodeficiency virus (HIV) particle is characterized by a conical capsid that encloses the viral RNA genome. The capsid is essential for HIV-1 replication and plays crucial roles in both early and late stages of the viral life cycle. Early on, upon fusion of the viral and cellular membranes, the viral capsid is released into the host cell cytoplasm and dissociates in a process known as uncoating, tightly associated with the reverse transcription of the viral genome. During the late stages of viral replication, the Gag polyprotein, precursor of the capsid protein, assemble at the plasma membrane to form immature non-infectious viral particles. After a maturation step by the viral protease, the capsid assembles to form a fullerene-like conical shape characteristic of the mature infectious particle. Mutations affecting the uncoating process, or capsid assembly and maturation, have been shown to hamper viral infectivity. The key role of capsid in viral replication and the absence of approved drugs against this protein have promoted the development of antiretrovirals. Screening based on the inhibition of capsid assembly and virtual screening for molecules binding to the capsid have successfully identified a number of potential small molecule compounds. Unfortunately, none of these molecules is currently used in the clinic. CONCLUSION Here we review the discovery and the mechanism of action of the small molecules and peptides identified as capsid inhibitors, and discuss their therapeutic potential.
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Affiliation(s)
| | - Susana T Valente
- Department Immunology and Microbial Sciences, The Scripps Research Institute, 130 Scripps Way, 3C1, Jupiter, FL 33458, USA.
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43
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Ning J, Erdemci-Tandogan G, Yufenyuy EL, Wagner J, Himes BA, Zhao G, Aiken C, Zandi R, Zhang P. In vitro protease cleavage and computer simulations reveal the HIV-1 capsid maturation pathway. Nat Commun 2016; 7:13689. [PMID: 27958264 PMCID: PMC5159922 DOI: 10.1038/ncomms13689] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
HIV-1 virions assemble as immature particles containing Gag polyproteins that are processed by the viral protease into individual components, resulting in the formation of mature infectious particles. There are two competing models for the process of forming the mature HIV-1 core: the disassembly and de novo reassembly model and the non-diffusional displacive model. To study the maturation pathway, we simulate HIV-1 maturation in vitro by digesting immature particles and assembled virus-like particles with recombinant HIV-1 protease and monitor the process with biochemical assays and cryoEM structural analysis in parallel. Processing of Gag in vitro is accurate and efficient and results in both soluble capsid protein and conical or tubular capsid assemblies, seemingly converted from immature Gag particles. Computer simulations further reveal probable assembly pathways of HIV-1 capsid formation. Combining the experimental data and computer simulations, our results suggest a sequential combination of both displacive and disassembly/reassembly processes for HIV-1 maturation. Two competing models—disassembly/reassembly and displacive—have been proposed for how immature spherical HIV virions transform into mature particles with conical cores. Here the authors provide evidence that both disassembly/reassembly and displacive processes occur sequentially during the maturation process.
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Affiliation(s)
- Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | - Gonca Erdemci-Tandogan
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Ernest L Yufenyuy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Jef Wagner
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA
| | - Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | - Christopher Aiken
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Roya Zandi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.,Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK.,Electron Bio-Imaging Centre, Diamond Light Sources, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
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44
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Structure-Activity Relationships of the Human Immunodeficiency Virus Type 1 Maturation Inhibitor PF-46396. J Virol 2016; 90:8181-97. [PMID: 27384665 PMCID: PMC5008107 DOI: 10.1128/jvi.01075-16] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 06/27/2016] [Indexed: 11/20/2022] Open
Abstract
HIV-1 maturation inhibitors are a novel class of antiretroviral compounds that consist of two structurally distinct chemical classes: betulinic acid derivatives and the pyridone-based compound PF-46396. It is currently believed that both classes act by similar modes of action to generate aberrant noninfectious particles via inhibition of CA-SP1 cleavage during Gag proteolytic processing. In this study, we utilized a series of novel analogues with decreasing similarity to PF-46396 to determine the chemical groups within PF-46396 that contribute to antiviral activity, Gag binding, and the relationship between these essential properties. A spectrum of antiviral activity (active, intermediate, and inactive) was observed across the analogue series with respect to CA-SP1 cleavage and HIV-1 (NL4-3) replication kinetics in Jurkat T cells. We demonstrate that selected inactive analogues are incorporated into wild-type (WT) immature particles and that one inactive analogue is capable of interfering with PF-46396 inhibition of CA-SP1 cleavage. Mutations that confer PF-46396 resistance can impose a defective phenotype on HIV-1 that can be rescued in a compound-dependent manner. Some inactive analogues retained the capacity to rescue PF-46396-dependent mutants (SP1-A3V, SP1-A3T, and CA-P157S), implying that they can also interact with mutant Gag. The structure-activity relationships observed in this study demonstrate that (i) the tert-butyl group is essential for antiviral activity but is not an absolute requirement for Gag binding, (ii) the trifluoromethyl group is optimal but not essential for antiviral activity, and (iii) the 2-aminoindan group is important for antiviral activity and Gag binding but is not essential, as its replacement is tolerated. IMPORTANCE Combinations of antiretroviral drugs successfully treat HIV/AIDS patients; however, drug resistance problems make the development of new mechanistic drug classes an ongoing priority. HIV-1 maturation inhibitors are novel as they target the Gag protein, specifically by inhibiting CA-SP1 proteolytic cleavage. The lack of high-resolution structural information of the CA-SP1 target in Gag has hindered our understanding of the inhibitor-binding pocket and maturation inhibitor mode of action. Therefore, we utilized analogues of the maturation inhibitor PF-46396 as chemical tools to determine the chemical components of PF-46396 that contribute to antiviral activity and Gag binding and the relationship between these essential properties. This is the first study to report structure-activity relationships of the maturation inhibitor PF-46396. PF-46396 is chemically distinct from betulinic acid-derived maturation inhibitors; therefore, our data provide a foundation of knowledge that will aid our understanding of how structurally distinct maturation inhibitors act by similar modes of action.
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45
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Bayro MJ, Ganser-Pornillos BK, Zadrozny KK, Yeager M, Tycko R. Helical Conformation in the CA-SP1 Junction of the Immature HIV-1 Lattice Determined from Solid-State NMR of Virus-like Particles. J Am Chem Soc 2016; 138:12029-32. [PMID: 27593947 DOI: 10.1021/jacs.6b07259] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Maturation of HIV-1 requires disassembly of the Gag polyprotein lattice, which lines the viral membrane in the immature state, and subsequent assembly of the mature capsid protein lattice, which encloses viral RNA in the mature state. Metastability of the immature lattice has been proposed to depend on the existence of a structurally ordered, α-helical segment spanning the junction between capsid (CA) and spacer peptide 1 (SP1) subunits of Gag, a segment that is dynamically disordered in the mature capsid lattice. We report solid state nuclear magnetic resonance (ssNMR) measurements on the immature lattice in noncrystalline, spherical virus-like particles (VLPs) derived from Gag. The ssNMR data provide definitive evidence for this critical α-helical segment in the VLPs. Differences in ssNMR chemical shifts and signal intensities between immature and mature lattice assemblies also support a major rearrangement of intermolecular interactions in the maturation process, consistent with recent models from electron cryomicroscopy and X-ray crystallography.
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Affiliation(s)
- Marvin J Bayro
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Seridan G. Snyder Translational Research Building, 480 Ray C. Hunt Drive, Charlottesville, Virginia 22908, United States
| | - Kaneil K Zadrozny
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Seridan G. Snyder Translational Research Building, 480 Ray C. Hunt Drive, Charlottesville, Virginia 22908, United States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Seridan G. Snyder Translational Research Building, 480 Ray C. Hunt Drive, Charlottesville, Virginia 22908, United States.,Department of Medicine, Division of Cardiovascular Medicine, University of Virginia Health System , Charlottesville, Virginia 22908, United States.,Center for Membrane and Cell Physiology, University of Virginia School of Medicine , Charlottesville, Virginia 22908, United States
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
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46
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Wagner JM, Zadrozny KK, Chrustowicz J, Purdy MD, Yeager M, Ganser-Pornillos BK, Pornillos O. Crystal structure of an HIV assembly and maturation switch. eLife 2016; 5. [PMID: 27416583 PMCID: PMC4946879 DOI: 10.7554/elife.17063] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 06/13/2016] [Indexed: 12/25/2022] Open
Abstract
Virus assembly and maturation proceed through the programmed operation of molecular switches, which trigger both local and global structural rearrangements to produce infectious particles. HIV-1 contains an assembly and maturation switch that spans the C-terminal domain (CTD) of the capsid (CA) region and the first spacer peptide (SP1) of the precursor structural protein, Gag. The crystal structure of the CTD-SP1 Gag fragment is a goblet-shaped hexamer in which the cup comprises the CTD and an ensuing type II β-turn, and the stem comprises a 6-helix bundle. The β-turn is critical for immature virus assembly and the 6-helix bundle regulates proteolysis during maturation. This bipartite character explains why the SP1 spacer is a critical element of HIV-1 Gag but is not a universal property of retroviruses. Our results also indicate that HIV-1 maturation inhibitors suppress unfolding of the CA-SP1 junction and thereby delay access of the viral protease to its substrate. DOI:http://dx.doi.org/10.7554/eLife.17063.001 Viruses like HIV must undergo a process called maturation in order to successfully infect cells. Maturation involves a dramatic rearrangement in the architecture of the virus. That is to say, the virus’s internal protein coat – called the capsid – must change from an immature sphere into a mature cone-shaped coat. Notably, this maturation process is what is disrupted by the protease inhibitors that are a major component of anti-HIV drug cocktails. Structural changes in small portions of the capsid protein, termed molecular switches, commonly trigger the viral capsids to reorganize. The HIV capsid has two of these switches, and Wagner, Zadrozny et al. set out to understand how one of them – called the CA-SP1 switch – works. Solving the three-dimensional structure of the immature form of the CA-SP1 switch revealed that it forms a well-structured bundle of six helices. This helical bundle captures another section of the capsid protein that would otherwise be cut by a viral protease. The CA-SP1 switch therefore controls how quickly the protein is cut and the start of the maturation process. Wagner, Zadrozny et al. then discovered that other small molecule inhibitors of HIV, called maturation inhibitors, work by binding to and disrupting the transformation of the CA-SP1 switch. Finally, further experiments showed that the formation of the CA-SP1 helical bundle controls when the immature capsid shell forms and coordinates the process with the capsid gaining the genetic material of the virus. The new structure means that researchers now know what the HIV capsid looks like at the start and end of maturation. The next challenge will be to figure out exactly how the capsid changes from one form to the next as HIV matures. DOI:http://dx.doi.org/10.7554/eLife.17063.002
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Affiliation(s)
- Jonathan M Wagner
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
| | - Kaneil K Zadrozny
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
| | - Jakub Chrustowicz
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States.,Department of Medicine, Division of Cardiovascular Medicine, University of Virginia Health System, Charlottesville, United States
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, United States
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47
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Schur FKM, Obr M, Hagen WJH, Wan W, Jakobi AJ, Kirkpatrick JM, Sachse C, Kräusslich HG, Briggs JAG. An atomic model of HIV-1 capsid-SP1 reveals structures regulating assembly and maturation. Science 2016; 353:506-8. [PMID: 27417497 DOI: 10.1126/science.aaf9620] [Citation(s) in RCA: 304] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/29/2016] [Indexed: 12/28/2022]
Abstract
Immature HIV-1 assembles at and buds from the plasma membrane before proteolytic cleavage of the viral Gag polyprotein induces structural maturation. Maturation can be blocked by maturation inhibitors (MIs), thereby abolishing infectivity. The CA (capsid) and SP1 (spacer peptide 1) region of Gag is the key regulator of assembly and maturation and is the target of MIs. We applied optimized cryo-electron tomography and subtomogram averaging to resolve this region within assembled immature HIV-1 particles at 3.9 angstrom resolution and built an atomic model. The structure reveals a network of intra- and intermolecular interactions mediating immature HIV-1 assembly. The proteolytic cleavage site between CA and SP1 is inaccessible to protease. We suggest that MIs prevent CA-SP1 cleavage by stabilizing the structure, and MI resistance develops by destabilizing CA-SP1.
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Affiliation(s)
- Florian K M Schur
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany. Molecular Medicine Partnership Unit, European Molecular Biology Laboratory-Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Martin Obr
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory-Universitätsklinikum Heidelberg, Heidelberg, Germany. Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Wim J H Hagen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - William Wan
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Arjen J Jakobi
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany. Hamburg Unit c/o DESY (Deutsches Elektronen-Synchrotron), European Molecular Biology Laboratory, Notkestraße 85, 22607 Hamburg, Germany
| | - Joanna M Kirkpatrick
- Proteomics Core Facility, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Carsten Sachse
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory-Universitätsklinikum Heidelberg, Heidelberg, Germany. Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, 69117 Heidelberg, Germany. Molecular Medicine Partnership Unit, European Molecular Biology Laboratory-Universitätsklinikum Heidelberg, Heidelberg, Germany.
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Identification of potent maturation inhibitors against HIV-1 clade C. Sci Rep 2016; 6:27403. [PMID: 27264714 PMCID: PMC4893694 DOI: 10.1038/srep27403] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/18/2016] [Indexed: 12/05/2022] Open
Abstract
Antiretroviral therapy has led to a profound improvement in the clinical care of HIV-infected patients. However, drug tolerability and the evolution of drug resistance have limited treatment options for many patients. Maturation inhibitors are a new class of antiretroviral agents for treatment of HIV-1. They act by interfering with the maturation of the virus by blocking the last step in Gag processing: the cleavage of the capsid-spacer peptide 1 (CA-SP1) intermediate to mature CA by the viral protease (PR). The first-in-class maturation inhibitor bevirimat (BVM) failed against a subset of HIV-1 isolates in clinical trials due to polymorphisms present in the CA-SP1 region of the Gag protein. Sequence analysis indicated that these polymorphisms are more common in non-clade B strains of HIV-1 such as HIV-1 clade C. Indeed, BVM was found to be ineffective against HIV-1 clade C molecular clones tested in this study. A number of BVM analogs were synthesized by chemical modifications at the C-28 position to improve its activity. The new BVM analogs displayed potent activity against HIV-1 clade B and C and also reduced infectivity of the virus. This study identifies novel and broadly active BVM analogs that may ultimately demonstrate efficacy in the clinic.
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Three-Dimensional Structural Characterization of HIV-1 Tethered to Human Cells. J Virol 2015; 90:1507-21. [PMID: 26582000 DOI: 10.1128/jvi.01880-15] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 11/14/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Tetherin (BST2, CD317, or HM1.24) is a host cellular restriction factor that prevents the release of enveloped viruses by mechanically linking virions to the plasma membrane. The precise arrangement of tetherin molecules at the plasma membrane site of HIV-1 assembly, budding, and restriction is not well understood. To gain insight into the biophysical mechanism underlying tetherin-mediated restriction of HIV-1, we utilized cryo-electron tomography (cryo-ET) to directly visualize HIV-1 virus-like particles (VLPs) and virions tethered to human cells in three dimensions (3D). Rod-like densities that we refer to as tethers were seen connecting HIV-1 virions to each other and to the plasma membrane. Native immunogold labeling showed tetherin molecules located on HIV-1 VLPs and virions in positions similar to those of the densities observed by cryo-ET. The location of the tethers with respect to the ordered immature Gag lattice or mature conical core was random. However, tethers were not uniformly distributed on the viral membrane but rather formed clusters at sites of contact with the cell or other virions. Chains of tethered HIV-1 virions often were arranged in a linear fashion, primarily as single chains and, to a lesser degree, as branched chains. Distance measurements support the extended tetherin model, in which the coiled-coil ectodomains are oriented perpendicular with respect to the viral and plasma membranes. IMPORTANCE Tetherin is a cellular factor that restricts HIV-1 release by directly cross-linking the virus to the host cell plasma membrane. We used cryo-electron tomography to visualize HIV-1 tethered to human cells in 3D. We determined that tetherin-restricted HIV-1 virions were physically connected to each other or to the plasma membrane by filamentous tethers that resembled rods ∼15 nm in length, which is consistent with the extended tetherin model. In addition, we found the position of the tethers to be arbitrary relative to the ordered immature Gag lattice or the mature conical cores. However, when present as multiple copies, the tethers clustered at the interface between virions. Tethered HIV-1 virions were arranged in a linear fashion, with the majority as single chains. This study advances our understanding of tetherin-mediated HIV-1 restriction by defining the spatial arrangement and orientation of tetherin molecules at sites of HIV-1 restriction.
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Identification of an HIV-1 Mutation in Spacer Peptide 1 That Stabilizes the Immature CA-SP1 Lattice. J Virol 2015; 90:972-8. [PMID: 26537676 DOI: 10.1128/jvi.02204-15] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/27/2015] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Upon release of HIV-1 particles from the infected cell, the viral protease cleaves the Gag polyprotein at specific sites, triggering maturation. During this process, which is essential for infectivity, the capsid protein (CA) reassembles into a conical core. Maturation inhibitors (MIs) block HIV-1 maturation by interfering with protease-mediated CA-spacer peptide 1 (CA-SP1) processing, concomitantly stabilizing the immature CA-SP1 lattice; virions from MI-treated cells retain an immature-like CA-SP1 lattice, whereas mutational abolition of cleavage at the CA-SP1 site results in virions in which the CA-SP1 lattice converts to a mature-like form. We previously reported that propagation of HIV-1 in the presence of MI PF-46396 selected for assembly-defective, compound-dependent mutants with amino acid substitutions in the major homology region (MHR) of CA. Propagation of these mutants in the absence of PF-46396 resulted in the acquisition of second-site compensatory mutations. These included a Thr-to-Ile substitution at SP1 residue 8 (T8I), which results in impaired CA-SP1 processing. Thus, the T8I mutation phenocopies PF-46396 treatment in terms of its ability to rescue the replication defect imposed by the MHR mutations and to impede CA-SP1 processing. Here, we use cryo-electron tomography to show that, like MIs, the T8I mutation stabilizes the immature-like CA-SP1 lattice. These results have important implications for the mechanism of action of HIV-1 MIs; they also suggest that T8I may provide a valuable tool for structural definition of the CA-SP1 boundary region, which has thus far been refractory to high-resolution analysis, apparently because of conformational flexibility in this region of Gag. IMPORTANCE HIV-1 maturation involves dissection of the Gag polyprotein by the viral protease and assembly of a conical capsid enclosing the viral ribonucleoprotein. Maturation inhibitors (MIs) prevent the final cleavage step at the site between the capsid protein (CA) and spacer peptide 1 (SP1), apparently by binding at this site and denying the protease access. Additionally, MIs stabilize the immature-like CA-SP1 lattice, preventing release of CA into the soluble pool. We previously found that T8I, a mutation in SP1, rescues a PF-46396-dependent CA mutant and blocks CA-SP1 cleavage. In this study, we imaged T8I virions by cryo-electron tomography and showed that T8I mutants, like MI-treated virions, contain an immature CA-SP1 lattice. These results lay the groundwork needed to understand the structure of the CA-SP1 interface region and further illuminate the mechanism of action of MIs.
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