1
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Layish B, Goli R, Flick H, Huang SW, Zhang RZ, Kvaratskhelia M, Kane M. Virus specificity and nucleoporin requirements for MX2 activity are affected by GTPase function and capsid-CypA interactions. PLoS Pathog 2024; 20:e1011830. [PMID: 38512975 PMCID: PMC10986937 DOI: 10.1371/journal.ppat.1011830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 04/02/2024] [Accepted: 02/29/2024] [Indexed: 03/23/2024] Open
Abstract
Human myxovirus resistance 2 (MX2/MXB) is an interferon-induced GTPase that inhibits human immunodeficiency virus-1 (HIV-1) infection by preventing nuclear import of the viral preintegration complex. The HIV-1 capsid (CA) is the major viral determinant for sensitivity to MX2, and complex interactions between MX2, CA, nucleoporins (Nups), cyclophilin A (CypA), and other cellular proteins influence the outcome of viral infection. To explore the interactions between MX2, the viral CA, and CypA, we utilized a CRISPR-Cas9/AAV approach to generate CypA knock-out cell lines as well as cells that express CypA from its endogenous locus, but with specific point mutations that would abrogate CA binding but should not affect enzymatic activity or cellular function. We found that infection of CypA knock-out and point mutant cell lines with wild-type HIV-1 and CA mutants recapitulated the phenotypes observed upon cyclosporine A (CsA) addition, indicating that effects of CsA treatment are the direct result of blocking CA-CypA interactions and are therefore independent from potential interactions between CypA and MX2 or other cellular proteins. Notably, abrogation of GTP hydrolysis by MX2 conferred enhanced antiviral activity when CA-CypA interactions were abolished, and this effect was not mediated by the CA-binding residues in the GTPase domain, or by phosphorylation of MX2 at position T151. We additionally found that elimination of GTPase activity also altered the Nup requirements for MX2 activity. Our data demonstrate that the antiviral activity of MX2 is affected by CypA-CA interactions in a virus-specific and GTPase activity-dependent manner. These findings further highlight the importance of the GTPase domain of MX2 in regulation of substrate specificity and interaction with nucleocytoplasmic trafficking pathways.
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Affiliation(s)
- Bailey Layish
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Ram Goli
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Haley Flick
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Szu-Wei Huang
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Robert Z. Zhang
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Mamuka Kvaratskhelia
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States of America
| | - Melissa Kane
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
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2
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Layish B, Goli R, Flick H, Huang SW, Zhang RZ, Kvaratskhelia M, Kane M. Virus specificity and nucleoporin requirements for MX2 activity are affected by GTPase function and capsid-CypA interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.16.567336. [PMID: 38014352 PMCID: PMC10680775 DOI: 10.1101/2023.11.16.567336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Human myxovirus resistance 2 (MX2/MXB) is an interferon-induced GTPase that inhibits human immunodeficiency virus-1 (HIV-1) infection by preventing nuclear import of the viral preintegration complex. The HIV-1 capsid (CA) is the major viral determinant for sensitivity to MX2, and complex interactions between MX2, CA, nucleoporins (Nups), cyclophilin A (CypA), and other cellular proteins influence the outcome of viral infection. To explore the interactions between MX2, the viral CA, and CypA, we utilized a CRISPR-Cas9/AAV approach to generate CypA knock-out cell lines as well as cells that express CypA from its endogenous locus, but with specific point mutations that would abrogate CA binding but should not affect enzymatic activity or cellular function. We found that infection of CypA knock-out and point mutant cell lines with wild-type HIV-1 and CA mutants recapitulated the phenotypes observed upon cyclosporine A (CsA) addition, indicating that effects of CsA treatment are the direct result of blocking CA-CypA interactions and are therefore independent from potential interactions between CypA and MX2 or other cellular proteins. Notably, abrogation of GTP hydrolysis by MX2 conferred enhanced antiviral activity when CA-CypA interactions were abolished, and this effect was not mediated by the CA-binding residues in the GTPase domain, or by phosphorylation of MX2 at position T151. We additionally found that elimination of GTPase activity also altered the Nup requirements for MX2 activity. Our data demonstrate that the antiviral activity of MX2 is affected by CypA-CA interactions in a virus-specific and GTPase activity-dependent manner. These findings further highlight the importance of the GTPase domain of MX2 in regulation of substrate specificity and interaction with nucleocytoplasmic trafficking pathways.
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Affiliation(s)
- Bailey Layish
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Ram Goli
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Haley Flick
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Szu-Wei Huang
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Robert Z Zhang
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Mamuka Kvaratskhelia
- Division of Infectious Diseases, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Melissa Kane
- Department of Pediatrics, Division of Infectious Diseases, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
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3
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Sengupta S, Zhang J, Reed MC, Yu J, Kim A, Boronina TN, Board NL, Wrabl JO, Shenderov K, Welsh RA, Yang W, Timmons AE, Hoh R, Cole RN, Deeks SG, Siliciano JD, Siliciano RF, Sadegh-Nasseri S. A cell-free antigen processing system informs HIV-1 epitope selection and vaccine design. J Exp Med 2023; 220:e20221654. [PMID: 37058141 PMCID: PMC10114365 DOI: 10.1084/jem.20221654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 02/01/2023] [Accepted: 03/23/2023] [Indexed: 04/15/2023] Open
Abstract
Distinct CD4+ T cell epitopes have been associated with spontaneous control of HIV-1 replication, but analysis of antigen-dependent factors that influence epitope selection is lacking. To examine these factors, we used a cell-free antigen processing system that incorporates soluble HLA-DR (DR1), HLA-DM (DM), cathepsins, and full-length protein antigens for epitope identification by LC-MS/MS. HIV-1 Gag, Pol, Env, Vif, Tat, Rev, and Nef were examined using this system. We identified 35 novel epitopes, including glycopeptides. Epitopes from smaller HIV-1 proteins mapped to regions of low protein stability and higher solvent accessibility. HIV-1 antigens associated with limited CD4+ T cell responses were processed efficiently, while some protective epitopes were inefficiently processed. 55% of epitopes obtained from cell-free processing induced memory CD4+ T cell responses in HIV-1+ donors, including eight of 19 novel epitopes tested. Thus, an in vitro processing system utilizing the components of Class II processing reveals factors influencing epitope selection of HIV-1 and represents an approach to understanding epitope selection from non-HIV-1 antigens.
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Affiliation(s)
- Srona Sengupta
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- The Graduate Program in Immunology and Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Josephine Zhang
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Madison C. Reed
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jeanna Yu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Aeryon Kim
- Department of Inflammation and Oncology and Genome Analysis Unit, Amgen Research, Amgen Inc., South San Francisco, CA, USA
| | - Tatiana N. Boronina
- Department of Biological Chemistry, Mass Spectrometry and Proteomics Facility, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nathan L. Board
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - James O. Wrabl
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Kevin Shenderov
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robin A. Welsh
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Weiming Yang
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Andrew E. Timmons
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Rebecca Hoh
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Robert N. Cole
- Department of Biological Chemistry, Mass Spectrometry and Proteomics Facility, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Steven G. Deeks
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Janet D. Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert F. Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Howard Hughes Medical Institute, Baltimore, MD, USA
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4
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Sato Y, Matsugami A, Watanabe S, Hayashi F, Arai M, Kigawa T, Nishimura C. Changes in dynamic and static structures of the HIV-1 p24 capsid protein N-domain caused by amino-acid substitution are associated with its viral viability. Protein Sci 2021; 30:2233-2245. [PMID: 34523753 DOI: 10.1002/pro.4184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 08/16/2021] [Accepted: 08/31/2021] [Indexed: 11/06/2022]
Abstract
HIV-1 capsid is comprised of over a hundred p24 protein molecules, arranged as either pentamers or hexamers. Three p24 mutants with amino acid substitutions in capsid N-terminal domain protein were examined: G60W (α3-4 loop), M68T (helix 4), and P90T (α4-5 loop), which exhibited no viability for biological activity. One common structural feature of the three p24 N-domain mutants, examined by NMR, was the long-range effect of more β-structures at the β2-strand in the N-terminal region compared with the wild-type. In addition, the presence of fewer helical structures was observed in M68T and P90T, beyond the broad area from helix 1 to the C-terminal part of helix 4. This suggests that both N-terminal beta structures and helices play important roles in the formation of p24 hexamers and pentamers. Next, compared with P90T, we examined cis-conformation or trans-conformation of wild-type adopted by isomerization at G89-P90. Since P90T mutant adopts only a trans-conformation, comparison of chemical shifts and signal intensities between each spectra revealed that the major peaks (about 85%) in the spectrum of wild-type correspond to trans-conformation. Furthermore, it was indicated that the region in cis-conformation (minor; 15%) was more stabilized than that observed in trans-conformation, based on the analyses of heteronuclear Overhauser effect as well as the order-parameter. Therefore, it was concluded that the cis-conformation is more favorable than the trans-conformation for the interaction between the p24 N-terminal domain and cyclophilin-A. This is because HIV-1 with a P90T protein, which adopts only a trans-conformation, is associated with non-viability of biological activity.
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Affiliation(s)
- Yusuke Sato
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Japan
| | - Akimasa Matsugami
- Advanced NMR Application and Platform Team, NMR Research and Collaboration Group, NMR Science and Development Division, RIKEN SPring-8 Center (RSC), Yokohama, Japan
| | - Satoru Watanabe
- Laboratory for Cellular Structural Biology, RIKEN Center for Biosystems, Dynamics Research, Yokohama, Japan
| | - Fumiaki Hayashi
- Advanced NMR Application and Platform Team, NMR Research and Collaboration Group, NMR Science and Development Division, RIKEN SPring-8 Center (RSC), Yokohama, Japan
| | - Munehito Arai
- Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Japan
| | - Takanori Kigawa
- Laboratory for Cellular Structural Biology, RIKEN Center for Biosystems, Dynamics Research, Yokohama, Japan.,School of Computing, Tokyo Institute of Technology, Yokohama, Japan
| | - Chiaki Nishimura
- Faculty of Pharmaceutical Sciences, Teikyo Heisei University, Nakano, Japan
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5
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Asija K, Teschke CM. Of capsid structure and stability: The partnership between charged residues of E-loop and P-domain of the bacteriophage P22 coat protein. Virology 2019; 534:45-53. [PMID: 31176063 PMCID: PMC6614003 DOI: 10.1016/j.virol.2019.05.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/27/2019] [Accepted: 05/31/2019] [Indexed: 01/14/2023]
Abstract
Tailed dsDNA bacteriophages and herpesviruses form capsids using coat proteins that have the HK97 fold. In these viruses, the coat proteins first assemble into procapsids, which subsequently mature during DNA packaging. Generally interactions between the coat protein E-loop of one subunit and the P-domain of an adjacent subunit help stabilize both capsomers and capsids. Based on a recent 3.3 Å cryo-EM structure of the bacteriophage P22 virion, E-loop amino acids E52, E59 and E72 were suggested to stabilize the capsid through intra-capsomer salt bridges with the P-domain residues R102, R109 and K118. The glutamic acid residues were each mutated to alanine to test this hypothesis. The substitutions resulted in a WT phenotype and did not destabilize capsids; rather, the alanine substituted coat proteins increased the stability of procapsids and virions. These results indicate that different types of interactions must be used between the E-loop and P-domain to stabilize phage P22 procapsids and virions.
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Affiliation(s)
- Kunica Asija
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Carolyn M Teschke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA; Department of Chemistry, University of Connecticut, Storrs, CT, USA.
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6
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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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7
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Kane M, Rebensburg SV, Takata MA, Zang TM, Yamashita M, Kvaratskhelia M, Bieniasz PD. Nuclear pore heterogeneity influences HIV-1 infection and the antiviral activity of MX2. eLife 2018; 7:e35738. [PMID: 30084827 PMCID: PMC6101944 DOI: 10.7554/elife.35738] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 08/06/2018] [Indexed: 12/14/2022] Open
Abstract
HIV-1 accesses the nuclear DNA of interphase cells via a poorly defined process involving functional interactions between the capsid protein (CA) and nucleoporins (Nups). Here, we show that HIV-1 CA can bind multiple Nups, and that both natural and manipulated variation in Nup levels impacts HIV-1 infection in a manner that is strikingly dependent on cell-type, cell-cycle, and cyclophilin A (CypA). We also show that Nups mediate the function of the antiviral protein MX2, and that MX2 can variably inhibit non-viral NLS function. Remarkably, both enhancing and inhibiting effects of cyclophilin A and MX2 on various HIV-1 CA mutants could be induced or abolished by manipulating levels of the Nup93 subcomplex, the Nup62 subcomplex, NUP88, NUP214, RANBP2, or NUP153. Our findings suggest that several Nup-dependent 'pathways' are variably exploited by HIV-1 to target host DNA in a cell-type, cell-cycle, CypA and CA-sequence dependent manner, and are differentially inhibited by MX2.
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Affiliation(s)
- Melissa Kane
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
| | - Stephanie V Rebensburg
- Division of Infectious DiseasesUniversity of Colorado School of MedicineAuroraUnited States
| | - Matthew A Takata
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
| | - Trinity M Zang
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical InstituteNew YorkUnited States
| | | | - Mamuka Kvaratskhelia
- Division of Infectious DiseasesUniversity of Colorado School of MedicineAuroraUnited States
| | - Paul D Bieniasz
- Laboratory of RetrovirologyThe Rockefeller UniversityNew YorkUnited States
- Howard Hughes Medical InstituteNew YorkUnited States
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8
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Folio C, Sierra N, Dujardin M, Alvarez G, Guillon C. Crystal Structure of the Full-Length Feline Immunodeficiency Virus Capsid Protein Shows an N-Terminal β-Hairpin in the Absence of N-Terminal Proline. Viruses 2017; 9:v9110335. [PMID: 29120364 PMCID: PMC5707542 DOI: 10.3390/v9110335] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/03/2017] [Accepted: 11/08/2017] [Indexed: 12/31/2022] Open
Abstract
Feline immunodeficiency virus (FIV) is a member of the Retroviridae family. It is the causative agent of an acquired immunodeficiency syndrome (AIDS) in cats and wild felines. Its capsid protein (CA) drives the assembly of the viral particle, which is a critical step in the viral replication cycle. Here, the first atomic structure of full-length FIV CA to 1.67 Å resolution is determined. The crystallized protein exhibits an original tetrameric assembly, composed of dimers which are stabilized by an intermolecular disulfide bridge induced by the crystallogenesis conditions. The FIV CA displays a standard α-helical CA topology with two domains, separated by a linker shorter than other retroviral CAs. The β-hairpin motif at its amino terminal end, which interacts with nucleotides in HIV-1, is unusually long in FIV CA. Interestingly, this functional β-motif is formed in this construct in the absence of the conserved N-terminal proline. The FIV CA exhibits a cis Arg–Pro bond in the CypA-binding loop, which is absent in known structures of lentiviral CAs. This structure represents the first tri-dimensional structure of a functional, full-length FIV CA.
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Affiliation(s)
- Christelle Folio
- Equipe Rétrovirus et Biochimie Structurale, Université de Lyon, CNRS, MMSB, UMR 5086 CNRS/Université de Lyon, IBCP, Lyon 69367 CEDEX 07, France.
| | - Natalia Sierra
- Laboratorio de Moléculas Bioactivas, Centro Universitario Regional Litoral Norte, Universidad de la República, Paysandú 60000, Uruguay.
| | - Marie Dujardin
- Equipe Rétrovirus et Biochimie Structurale, Université de Lyon, CNRS, MMSB, UMR 5086 CNRS/Université de Lyon, IBCP, Lyon 69367 CEDEX 07, France.
| | - Guzman Alvarez
- Laboratorio de Moléculas Bioactivas, Centro Universitario Regional Litoral Norte, Universidad de la República, Paysandú 60000, Uruguay.
| | - Christophe Guillon
- Equipe Rétrovirus et Biochimie Structurale, Université de Lyon, CNRS, MMSB, UMR 5086 CNRS/Université de Lyon, IBCP, Lyon 69367 CEDEX 07, France.
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9
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Miyazaki Y, Miyake A, Doi N, Koma T, Uchiyama T, Adachi A, Nomaguchi M. Comparison of Biochemical Properties of HIV-1 and HIV-2 Capsid Proteins. Front Microbiol 2017; 8:1082. [PMID: 28659897 PMCID: PMC5469281 DOI: 10.3389/fmicb.2017.01082] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 05/29/2017] [Indexed: 01/08/2023] Open
Abstract
Timely disassembly of viral core composed of self-assembled capsid (CA) in infected host cells is crucial for retroviral replication. Extensive in vitro studies to date on the self-assembly/disassembly mechanism of human immunodeficiency virus type 1 (HIV-1) CA have revealed its core structure and amino acid residues essential for CA–CA intermolecular interaction. However, little is known about in vitro properties of HIV-2 CA. In this study, we comparatively analyzed the polymerization properties of bacterially expressed HIV-1 and HIV-2 CA proteins. Interestingly, a much higher concentration of NaCl was required for HIV-2 CA to self-assemble than that for HIV-1 CA, but once the polymerization started, the reaction proceeded more rapidly than that observed for HIV-1 CA. Analysis of a chimeric protein revealed that N-terminal domain (NTD) is responsible for this unique property of HIV-2 CA. To further study the molecular basis for different in vitro properties of HIV-1 and HIV-2 CA proteins, we determined thermal stabilities of HIV-1 and HIV-2 CA NTD proteins at several NaCl concentrations by fluorescent-based thermal shift assays. Experimental data obtained showed that HIV-2 CA NTD was structurally more stable than HIV-1 CA NTD. Taken together, our results imply that distinct in vitro polymerization abilities of the two CA proteins are related to their structural instability/stability, which is one of the decisive factors for viral replication potential. In addition, our assay system described here may be potentially useful for searching for anti-CA antivirals against HIV-1 and HIV-2.
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Affiliation(s)
- Yasuyuki Miyazaki
- Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical ScienceTokyo, Japan
| | - Ariko Miyake
- Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi UniversityYamaguchi, Japan
| | - Noya Doi
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Takaaki Koma
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Tsuneo Uchiyama
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Akio Adachi
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
| | - Masako Nomaguchi
- Department of Microbiology, Tokushima University Graduate School of Medical SciencesTokushima, Japan
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10
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In vitro assembly of the Rous Sarcoma Virus capsid protein into hexamer tubes at physiological temperature. Sci Rep 2017; 7:2913. [PMID: 28588198 PMCID: PMC5460288 DOI: 10.1038/s41598-017-02060-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/06/2017] [Indexed: 12/21/2022] Open
Abstract
During a proteolytically-driven maturation process, the orthoretroviral capsid protein (CA) assembles to form the convex shell that surrounds the viral genome. In some orthoretroviruses, including Rous Sarcoma Virus (RSV), CA carries a short and hydrophobic spacer peptide (SP) at its C-terminus early in the maturation process, which is progressively removed as maturation proceeds. In this work, we show that RSV CA assembles in vitro at near-physiological temperatures, forming hexamer tubes that effectively model the mature capsid surface. Tube assembly is strongly influenced by electrostatic effects, and is a nucleated process that remains thermodynamically favored at lower temperatures, but is effectively arrested by the large Gibbs energy barrier associated with nucleation. RSV CA tubes are multi-layered, being formed by nested and concentric tubes of capsid hexamers. However the spacer peptide acts as a layering determinant during tube assembly. If only a minor fraction of CA-SP is present, multi-layered tube formation is blocked, and single-layered tubes predominate. This likely prevents formation of biologically aberrant multi-layered capsids in the virion. The generation of single-layered hexamer tubes facilitated 3D helical image reconstruction from cryo-electron microscopy data, revealing the basic tube architecture.
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11
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Cortines JR, Lima LMT, Mohana-Borges R, Millen TDA, Gaspar LP, Lanman JK, Prevelige PE, Silva JL. Structural insights into the stabilization of the human immunodeficiency virus type 1 capsid protein by the cyclophilin-binding domain and implications on the virus cycle. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:341-8. [DOI: 10.1016/j.bbapap.2014.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 11/24/2014] [Accepted: 12/10/2014] [Indexed: 01/01/2023]
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12
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Zhao Y, Wang Y, Gao Y, Li G, Huang J. Integrated analysis of residue coevolution and protein structures capture key protein sectors in HIV-1 proteins. PLoS One 2015; 10:e0117506. [PMID: 25671429 PMCID: PMC4324911 DOI: 10.1371/journal.pone.0117506] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 12/24/2014] [Indexed: 02/07/2023] Open
Abstract
HIV type 1 (HIV-1) is characterized by its rapid genetic evolution, leading to challenges in anti-HIV therapy. However, the sequence variations in HIV-1 proteins are not randomly distributed due to a combination of functional constraints and genetic drift. In this study, we examined patterns of sequence variability for evidence of linked sequence changes (termed as coevolution or covariation) in 15 HIV-1 proteins. It shows that the percentage of charged residues in the coevolving residues is significantly higher than that in all the HIV-1 proteins. Most of the coevolving residues are spatially proximal in the protein structures and tend to form relatively compact and independent units in the tertiary structures, termed as "protein sectors". These protein sectors are closely associated with anti-HIV drug resistance, T cell epitopes, and antibody binding sites. Finally, we explored candidate peptide inhibitors based on the protein sectors. Our results can establish an association between the coevolving residues and molecular functions of HIV-1 proteins, and then provide us with valuable knowledge of pathology of HIV-1 and therapeutics development.
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Affiliation(s)
- Yuqi Zhao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, No.32 Jiaochang Donglu Kunming, 650223 Yunnan, China
- Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Drive East, Los Angeles, California, United States of America
- * E-mail: (YZ); (JH)
| | - Yanjie Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Yuedong Gao
- Kunming Biological Diversity Regional Center of Instruments, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Gonghua Li
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, No.32 Jiaochang Donglu Kunming, 650223 Yunnan, China
| | - Jingfei Huang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, No.32 Jiaochang Donglu Kunming, 650223 Yunnan, China
- Collaborative Innovation Center for Natural Products and Biological Drugs of Yunnan, Kunming, Yunnan 650223, China
- * E-mail: (YZ); (JH)
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13
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Bereszczak JZ, Watts NR, Wingfield PT, Steven AC, Heck AJR. Assessment of differences in the conformational flexibility of hepatitis B virus core-antigen and e-antigen by hydrogen deuterium exchange-mass spectrometry. Protein Sci 2014; 23:884-96. [PMID: 24715628 DOI: 10.1002/pro.2470] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/02/2014] [Accepted: 04/02/2014] [Indexed: 01/17/2023]
Abstract
Hepatitis B virus core-antigen (capsid protein) and e-antigen (an immune regulator) have almost complete sequence identity, yet the dimeric proteins (termed Cp149d and Cp(-10)149d , respectively) adopt quite distinct quaternary structures. Here we use hydrogen deuterium exchange-mass spectrometry (HDX-MS) to study their structural properties. We detect many regions that differ substantially in their HDX dynamics. Significantly, whilst all regions in Cp(-10)149d exchange by EX2-type kinetics, a number of regions in Cp149d were shown to exhibit a mixture of EX2- and EX1-type kinetics, hinting at conformational heterogeneity in these regions. Comparison of the HDX of the free Cp149d with that in assembled capsids (Cp149c ) indicated increased resistance to exchange at the C-terminus where the inter-dimer contacts occur. Furthermore, evidence of mixed exchange kinetics were not observed in Cp149c , implying a reduction in flexibility upon capsid formation. Cp(-10)149d undergoes a drastic structural change when the intermolecular disulphide bridge is reduced, adopting a Cp149d -like structure, as evidenced by the detected HDX dynamics being more consistent with Cp149d in many, albeit not all, regions. These results demonstrate the highly dynamic nature of these similar proteins. To probe the effect of these structural differences on the resulting antigenicity, we investigated binding of the antibody fragment (Fab E1) that is known to bind a conformational epitope on the four-helix bundle. Whilst Fab E1 binds to Cp149c and Cp149d , it does not bind non-reduced and reduced Cp(-10)149d , despite unhindered access to the epitope. These results imply a remarkable sensitivity of this epitope to its structural context.
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Affiliation(s)
- Jessica Z Bereszczak
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands; Netherlands Proteomics Centre, The Netherlands
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14
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López CS, Tsagli SM, Sloan R, Eccles J, Barklis E. Second site reversion of a mutation near the amino terminus of the HIV-1 capsid protein. Virology 2013; 447:95-103. [PMID: 24210103 DOI: 10.1016/j.virol.2013.08.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2013] [Revised: 08/20/2013] [Accepted: 08/21/2013] [Indexed: 11/19/2022]
Abstract
During HIV-1 morphogenesis, the precursor Gag protein is processed to release capsid (CA) proteins that form the mature virus core. In this process, the CA proteins assemble a lattice in which N-terminal domain (NTD) helices 1-3 are critical for multimer formation. Mature core assembly requires refolding of the N-terminus of CA into a β-hairpin, but the precise contribution of the hairpin core morphogenesis is unclear. We found that mutations at isoleucine 15 (I15), between the β-hairpin and NTD helix 1 are incompatible with proper mature core assembly. However, a compensatory mutation of histidine 12 in the β-hairpin to a tyrosine was selected by long term passage of an I15 mutant virus in T cells. The tyrosine does not interact directly with residue 15, but with NTD helix 3, supporting a model in which β-hairpin folding serves to align helix 3 for mature NTD multimerization.
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Affiliation(s)
- Claudia S López
- Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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15
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Bereszczak JZ, Rose RJ, van Duijn E, Watts NR, Wingfield PT, Steven AC, Heck AJR. Epitope-distal effects accompany the binding of two distinct antibodies to hepatitis B virus capsids. J Am Chem Soc 2013; 135:6504-12. [PMID: 23597076 PMCID: PMC3658141 DOI: 10.1021/ja402023x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Infection of humans by hepatitis B virus (HBV) induces the copious production of antibodies directed against the capsid protein (Cp). A large variety of anticapsid antibodies have been identified that differ in their epitopes. These data, and the status of the capsid as a major clinical antigen, motivate studies to achieve a more detailed understanding of their interactions. In this study, we focused on the Fab fragments of two monoclonal antibodies, E1 and 3120. E1 has been shown to bind to the side of outward-protruding spikes whereas 3120 binds to the "floor" region of the capsid, between spikes. We used hydrogen-deuterium exchange coupled to mass spectrometry (HDX-MS) to investigate the effects on HBV capsids of binding these antibodies. Conventionally, capsids loaded with saturating amounts of Fabs would be too massive to be readily amenable to HDX-MS. However, by focusing on the Cp protein, we were able to acquire deuterium uptake profiles covering the entire 149-residue sequence and reveal, in localized detail, changes in H/D exchange rates accompanying antibody binding. We find increased protection of the known E1 and 3120 epitopes on the capsid upon binding and show that regions distant from the epitopes are also affected. In particular, the α2a helix (residues 24-34) and the mobile C-terminus (residues 141-149) become substantially less solvent-exposed. Our data indicate that even at substoichiometric antibody binding an overall increase in the rigidity of the capsid is elicited, as well as a general dampening of its breathing motions.
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Affiliation(s)
- Jessica Z. Bereszczak
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- The Netherlands Proteomics Centre, The Netherlands
| | - Rebecca J. Rose
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- The Netherlands Proteomics Centre, The Netherlands
| | - Esther van Duijn
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- The Netherlands Proteomics Centre, The Netherlands
| | - Norman R. Watts
- Protein Expression Laboratory, National Institute for Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda MD 20892, USA
| | - Paul T. Wingfield
- Protein Expression Laboratory, National Institute for Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda MD 20892, USA
| | - Alasdair C. Steven
- Laboratory of Structural Biology, National Institute for Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda MD 20892, USA
| | - Albert J. R. Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute of Pharmaceutical Sciences, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- The Netherlands Proteomics Centre, The Netherlands
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16
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Biophysical characterization of the feline immunodeficiency virus p24 capsid protein conformation and in vitro capsid assembly. PLoS One 2013; 8:e56424. [PMID: 23457565 PMCID: PMC3574121 DOI: 10.1371/journal.pone.0056424] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 01/10/2013] [Indexed: 12/27/2022] Open
Abstract
The Feline Immunodeficiency Virus (FIV) capsid protein p24 oligomerizes to form a closed capsid that protects the viral genome. Because of its crucial role in the virion, FIV p24 is an interesting target for the development of therapeutic strategies, although little is known about its structure and assembly. We defined and optimized a protocol to overexpress recombinant FIV capsid protein in a bacterial system. Circular dichroism and isothermal titration calorimetry experiments showed that the structure of the purified FIV p24 protein was comprised mainly of α-helices. Dynamic light scattering (DLS) and cross-linking experiments demonstrated that p24 was monomeric at low concentration and dimeric at high concentration. We developed a protocol for the in vitro assembly of the FIV capsid. As with HIV, an increased ionic strength resulted in FIV p24 assembly in vitro. Assembly appeared to be dependent on temperature, salt concentration, and protein concentration. The FIV p24 assembly kinetics was monitored by DLS. A limit end-point diameter suggested assembly into objects of definite shapes. This was confirmed by electron microscopy, where FIV p24 assembled into spherical particles. Comparison of FIV p24 with other retroviral capsid proteins showed that FIV assembly is particular and requires further specific study.
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17
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Neira JL. Fluorescence, circular dichroism and mass spectrometry as tools to study virus structure. Subcell Biochem 2013; 68:177-202. [PMID: 23737052 DOI: 10.1007/978-94-007-6552-8_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Fluorescence and circular dichroism, as analytical spectroscopic techniques, and mass spectrometry as an analytical tool to determine the molecular mass, provide important biophysical approaches in structural virology. Although they do not provide atomic, or near-atomic, details as electron microscopy, X-ray crystallography or nuclear magnetic resonance spectroscopy can do, they do provide important insights into virus particle composition, structure, conformational stability and dynamics, assembly and maturation, and interactions with other viral and cellular biomolecules. They can be used also to investigate the molecular determinants of virus particle structure and properties, and the changes induced in them by external factors. In this chapter, I describe the physical bases of these three techniques, and some examples on how they have helped us to understand virus particle structure and physicochemical properties.
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Affiliation(s)
- José L Neira
- Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202, Elche, Alicante, Spain,
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18
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Chen K, Piszczek G, Carter C, Tjandra N. The maturational refolding of the β-hairpin motif of equine infectious anemia virus capsid protein extends its helix α1 at capsid assembly locus. J Biol Chem 2012. [PMID: 23184932 PMCID: PMC3548464 DOI: 10.1074/jbc.m112.425140] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
A retroviral capsid (CA) protein consists of two helical domains, CAN and CAC, which drive hexamer and dimer formations, respectively, to form a capsid lattice. The N-terminal 13 residues of CA refold to a β-hairpin motif upon processing from its precursor polyprotein Gag. The β-hairpin is essential for correct CA assembly but unexpectedly it is not within any CA oligomeric interfaces. To understand the β-hairpin function we studied the full-length CA protein from equine infectious anemia virus (EIAV), a lentivirus sharing the same cone-shaped capsid core as HIV-1. Solution NMR spectroscopy is perfectly suited to study EIAV-CA that dimerizes weaker than HIV-1-CA. Comparison between the wild-type (wt) EIAV-CA and a variant lacking the β-hairpin structure demonstrated that folding of the β-hairpin specifically extended the N terminus of helix α1 from Tyr20 to Pro17. This coil to helix transition involves the conserved sequence of Thr16-Pro17-Arg18 (Ser16-Pro17-Arg18 in HIV-1-CA). The extended region of helix α1 constituted an expanded EIAV-CAN oligomeric interface and overlapped with the HIV-1-CA hexamer-core residue Arg18, helical in structure and pivotal in assembly. Therefore we propose the function of the maturational refolding of the β-hairpin in CA assembly is to extend helix α1 at the N terminus to enhance the CAN oligomerization along the capsid assembly core interface. In addition, NMR resonance line broadening indicated the presence of micro-millisecond exchange kinetics due to the EIAV-CAN domain oligomerization, independent to the faster EIAV-CAC domain dimerization.
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Affiliation(s)
- Kang Chen
- Laboratory of Molecular Biophysics, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA
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19
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Bocanegra R, Rodríguez-Huete A, Fuertes MÁ, del Álamo M, Mateu MG. Molecular recognition in the human immunodeficiency virus capsid and antiviral design. Virus Res 2012; 169:388-410. [DOI: 10.1016/j.virusres.2012.06.016] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2012] [Revised: 06/11/2012] [Accepted: 06/12/2012] [Indexed: 01/07/2023]
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20
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Larue R, Gupta K, Wuensch C, Shkriabai N, Kessl JJ, Danhart E, Feng L, Taltynov O, Christ F, Van Duyne GD, Debyser Z, Foster MP, Kvaratskhelia M. Interaction of the HIV-1 intasome with transportin 3 protein (TNPO3 or TRN-SR2). J Biol Chem 2012; 287:34044-58. [PMID: 22872640 PMCID: PMC3464514 DOI: 10.1074/jbc.m112.384669] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 08/01/2012] [Indexed: 01/14/2023] Open
Abstract
Transportin 3 (TNPO3 or TRN-SR2) has been shown to be an important cellular factor for early steps of lentiviral replication. However, separate studies have implicated distinct mechanisms for TNPO3 either through its interaction with HIV-1 integrase or capsid. Here we have carried out a detailed biophysical characterization of TNPO3 and investigated its interactions with viral proteins. Biophysical analyses including circular dichroism, analytical ultracentrifugation, small-angle x-ray scattering, and homology modeling provide insight into TNPO3 architecture and indicate that it is highly structured and exists in a monomer-dimer equilibrium in solution. In vitro biochemical binding assays argued against meaningful direct interaction between TNPO3 and the capsid cores. Instead, TNPO3 effectively bound to the functional intasome but not to naked viral DNA, suggesting that TNPO3 can directly engage the HIV-1 IN tetramer prebound to the cognate DNA. Mass spectrometry-based protein footprinting and site-directed mutagenesis studies have enabled us to map several interacting amino acids in the HIV-1 IN C-terminal domain and the cargo binding domain of TNPO3. Our findings provide important information for future genetic analysis to better understand the role of TNPO3 and its interacting partners for HIV-1 replication.
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Affiliation(s)
- Ross Larue
- From the Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy and
| | - Kushol Gupta
- the Department of Biochemistry and Biophysics and The Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, and
| | - Christiane Wuensch
- From the Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy and
| | - Nikolozi Shkriabai
- From the Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy and
| | - Jacques J. Kessl
- From the Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy and
| | - Eric Danhart
- the Department of Chemistry,The Ohio State University, Columbus, Ohio 43210
| | - Lei Feng
- From the Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy and
| | - Oliver Taltynov
- the Division of Molecular Medicine, Katholieke Universiteit Leuven, Leuven, Flanders 3000, Belgium
| | - Frauke Christ
- the Division of Molecular Medicine, Katholieke Universiteit Leuven, Leuven, Flanders 3000, Belgium
| | - Gregory D. Van Duyne
- the Department of Biochemistry and Biophysics and The Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, and
| | - Zeger Debyser
- the Division of Molecular Medicine, Katholieke Universiteit Leuven, Leuven, Flanders 3000, Belgium
| | - Mark P. Foster
- the Department of Chemistry,The Ohio State University, Columbus, Ohio 43210
| | - Mamuka Kvaratskhelia
- From the Center for Retrovirus Research and Comprehensive Cancer Center, College of Pharmacy and
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21
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Meng X, Zhao G, Yufenyuy E, Ke D, Ning J, DeLucia M, Ahn J, Gronenborn AM, Aiken C, Zhang P. Protease cleavage leads to formation of mature trimer interface in HIV-1 capsid. PLoS Pathog 2012; 8:e1002886. [PMID: 22927821 PMCID: PMC3426514 DOI: 10.1371/journal.ppat.1002886] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 07/13/2012] [Indexed: 11/19/2022] Open
Abstract
During retrovirus particle maturation, the assembled Gag polyprotein is cleaved by the viral protease into matrix (MA), capsid (CA), and nucleocapsid (NC) proteins. To form the mature viral capsid, CA rearranges, resulting in a lattice composed of hexameric and pentameric CA units. Recent structural studies of assembled HIV-1 CA revealed several inter-subunit interfaces in the capsid lattice, including a three-fold interhexamer interface that is critical for proper capsid stability. Although a general architecture of immature particles has been provided by cryo-electron tomographic studies, the structural details of the immature particle and the maturation pathway remain unknown. Here, we used cryo-electron microscopy (cryoEM) to determine the structure of tubular assemblies of the HIV-1 CA-SP1-NC protein. Relative to the mature assembled CA structure, we observed a marked conformational difference in the position of the CA-CTD relative to the NTD in the CA-SP1-NC assembly, involving the flexible hinge connecting the two domains. This difference was verified via engineered disulfide crosslinking, revealing that inter-hexamer contacts, in particular those at the pseudo three-fold axis, are altered in the CA-SP1-NC assemblies compared to the CA assemblies. Results from crosslinking analyses of mature and immature HIV-1 particles containing the same Cys substitutions in the Gag protein are consistent with these findings. We further show that cleavage of preassembled CA-SP1-NC by HIV-1 protease in vitro leads to release of SP1 and NC without disassembly of the lattice. Collectively, our results indicate that the proteolytic cleavage of Gag leads to a structural reorganization of the polypeptide and creates the three-fold interhexamer interface, important for the formation of infectious HIV-1 particles.
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Affiliation(s)
- Xin Meng
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Ernest Yufenyuy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Danxia Ke
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Maria DeLucia
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Jinwoo Ahn
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Angela M. Gronenborn
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail: (CA); (PZ)
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, United States of America
- * E-mail: (CA); (PZ)
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22
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Brock A. Fragmentation hydrogen exchange mass spectrometry: A review of methodology and applications. Protein Expr Purif 2012; 84:19-37. [DOI: 10.1016/j.pep.2012.04.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Accepted: 04/13/2012] [Indexed: 01/19/2023]
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23
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Saeed M, Wilson M. Value of MR contrast media in image-guided body interventions. World J Radiol 2012; 4:1-12. [PMID: 22328966 PMCID: PMC3272615 DOI: 10.4329/wjr.v4.i1.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2011] [Revised: 10/28/2011] [Accepted: 11/04/2011] [Indexed: 02/06/2023] Open
Abstract
In the past few years, there have been multiple advances in magnetic resonance (MR) instrumentation, in vivo devices, real-time imaging sequences and interventional procedures with new therapies. More recently, interventionists have started to use minimally invasive image-guided procedures and local therapies, which reduce the pain from conventional surgery and increase drug effectiveness, respectively. Local therapy also reduces the systemic dose and eliminates the toxic side effects of some drugs to other organs. The success of MR-guided procedures depends on visualization of the targets in 3D and precise deployment of ablation catheters, local therapies and devices. MR contrast media provide a wealth of tissue contrast and allows 3D and 4D image acquisitions. After the development of fast imaging sequences, the clinical applications of MR contrast media have been substantially expanded to include pre- during- and post-interventions. Prior to intervention, MR contrast media have the potential to localize and delineate pathologic tissues of vital organs, such as the brain, heart, breast, kidney, prostate, liver and uterus. They also offer other options such as labeling therapeutic agents or cells. During intervention, these agents have the capability to map blood vessels and enhance the contrast between the endovascular guidewire/catheters/devices, blood and tissues as well as direct therapies to the target. Furthermore, labeling therapeutic agents or cells aids in visualizing their delivery sites and tracking their tissue distribution. After intervention, MR contrast media have been used for assessing the efficacy of ablation and therapies. It should be noted that most image-guided procedures are under preclinical research and development. It can be concluded that MR contrast media have great value in preclinical and some clinical interventional procedures. Future applications of MR contrast media in image-guided procedures depend on their safety, tolerability, tissue specificity and effectiveness in demonstrating success of the interventions and therapies.
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