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Ziegler A, Seelig J. High Affinity of the Cell-Penetrating Peptide HIV-1 Tat-PTD for DNA. Biochemistry 2007; 46:8138-45. [PMID: 17555330 DOI: 10.1021/bi700416h] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
During cellular uptake of fluorescently labeled cell-penetrating peptides (CPPs), intense fluorescent signals are commonly observed in the nucleus of the cell, suggesting intracellular CPP relocation and potential binding to the genome of the host. We therefore investigated the interaction of the CPP HIV-1 Tat(47-57) with double-stranded DNA, and we also tested whether the fluorescence intensity of the labeled CPP allows for linear predictions of its intracellular concentration. Using isothermal titration calorimetry, we observe that the CPP has a high affinity for salmon sperm DNA as characterized by a microscopic dissociation constant of 126 nM. The binding is exothermic, with a reaction enthalpy of -4.63 kcal/mol CPP (28 degrees C). The dissociation constant and reaction enthalpy decrease further at higher temperatures. The affinity of the CPP for DNA is thus 1-2 magnitudes higher than for extracellular heparan sulfate, the likely mediator of the CPP uptake. Accordingly, the high affinity for DNA confers stability to extracellular transport complexes of CPP and DNA but potentially affects the regulation and molecular organization of the host's genome after nuclear uptake. Moreover, the CPP leads to the condensation of DNA as evidenced by the pronounced increase in light-scattering intensity. The fluorescence quantum yield of the FITC-labeled CPP decreases considerably at concentrations > 5 micromol/L, at pH < 7, and upon binding to DNA and glycosaminoglycans. This change in fluorescence quantum yield impedes the microscopic identification of uptake routes and the comparison of uptake efficiency of different CPPs, especially if the accumulation in subcellular compartments (self-quenching and pH difference) and transitory binding partners (quenching and condensation) is unknown.
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Affiliation(s)
- André Ziegler
- Department of Biophysical Chemistry, Biozentrum, University of Basel, Kingelbergstrasse 50/70, 4056 Basel, Switzerland.
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2
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Modern High Resolution NMR for the Study of Structure, Dynamics and Interactions of Biological Macromolecules. Z PHYS CHEM 2006. [DOI: 10.1524/zpch.2006.220.5.567] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Hänel K, Stangler T, Stoldt M, Willbold D. Solution structure of the X4 protein coded by the SARS related coronavirus reveals an immunoglobulin like fold and suggests a binding activity to integrin I domains. J Biomed Sci 2005; 13:281-93. [PMID: 16328780 PMCID: PMC7089389 DOI: 10.1007/s11373-005-9043-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Accepted: 10/11/2005] [Indexed: 02/08/2023] Open
Abstract
The SARS related Coronavirus genome contains a variety of novel accessory genes. One of these, called ORF7a or ORF8, code for a protein, known as 7a, U122 or X4. We set out to determine the three-dimensional structure of the soluble ectodomain of this type-I transmembrane protein by nuclear magnetic resonance spectroscopy. The fold of the protein is the first member of a further variation of the immunoglobulin like beta-sandwich fold. Because X4 does not reveal significant sequence homologies to proteins in the data bases, we carried out a structure based similarity search for proteins with known function. High structural similarity to Dl domains of ICAM-1 and ICAM-2, and common features in amino acid sequence between X4 and ICAM-1, suggest X4 to possess binding activity for the alpha(L) integrin I domain of LFA-1. Further, based on this structure based prediction, potential functions of X4 in virus replication and pathogenesis are discussed.
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Affiliation(s)
- Karen Hänel
- Forschungszentrum Jülich, Institut für Biologische Informationsverarbeitung (IBI-2), 52425 Jülich, Germany
- Heinrich-Heine-Universität, Institut für Physikalische Biologie and BMFZ, 40225 Düsseldorf, Germany
| | - Thomas Stangler
- Forschungszentrum Jülich, Institut für Biologische Informationsverarbeitung (IBI-2), 52425 Jülich, Germany
- Heinrich-Heine-Universität, Institut für Physikalische Biologie and BMFZ, 40225 Düsseldorf, Germany
| | - Matthias Stoldt
- Forschungszentrum Jülich, Institut für Biologische Informationsverarbeitung (IBI-2), 52425 Jülich, Germany
- Heinrich-Heine-Universität, Institut für Physikalische Biologie and BMFZ, 40225 Düsseldorf, Germany
| | - Dieter Willbold
- Forschungszentrum Jülich, Institut für Biologische Informationsverarbeitung (IBI-2), 52425 Jülich, Germany
- Heinrich-Heine-Universität, Institut für Physikalische Biologie and BMFZ, 40225 Düsseldorf, Germany
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St-Louis MC, Cojocariu M, Archambault D. The molecular biology of bovine immunodeficiency virus: a comparison with other lentiviruses. Anim Health Res Rev 2005; 5:125-43. [PMID: 15984320 DOI: 10.1079/ahr200496] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Bovine immunodeficiency virus (BIV) was first isolated in 1969 from a cow, R-29, with a wasting syndrome. The virus isolated induced the formation of syncytia in cell cultures and was structurally similar to maedi-visna virus. Twenty years later, it was demonstrated that the bovine R-29 isolate was indeed a lentivirus with striking similarity to the human immunodeficiency virus. Like other lentiviruses, BIV has a complex genomic structure characterized by the presence of several regulatory/accessory genes that encode proteins, some of which are involved in the regulation of virus gene expression. This manuscript aims to review biological and, more particularly, molecular aspects of BIV, with emphasis on regulatory/accessory viral genes/proteins, in comparison with those of other lentiviruses.
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Affiliation(s)
- Marie-Claude St-Louis
- University of Québec at Montréal, Department of Biological Sciences, Montréal, Québec, Canada
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Brigati C, Giacca M, Noonan DM, Albini A. HIV Tat, its TARgets and the control of viral gene expression. FEMS Microbiol Lett 2003; 220:57-65. [PMID: 12644228 DOI: 10.1016/s0378-1097(03)00067-3] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The human immunodeficiency virus (HIV-1) (transactivator of transcription (Tat)) protein is a pleiotropic factor that induces a broad range of biological effects in numerous cell types. At the HIV promoter, Tat is a powerful transactivator of gene expression, which acts by both inducing chromatin remodeling and by recruiting elongation-competent transcriptional complexes onto the viral LTR. Besides these transcriptional activities, Tat is released outside the cells and interacts with different cell membrane-associated receptors. Finally, extracellular Tat can be internalized by cells through an active endocytosis process. Here we discuss some of the molecular mechanisms involved in intracellular and extracellular Tat function.
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MESH Headings
- Acetylation
- Acetyltransferases/metabolism
- Bacteriophage lambda/genetics
- Chromatin/genetics
- Chromatin/metabolism
- Endocytosis
- Extracellular Space/metabolism
- Gene Expression Regulation, Viral
- Gene Products, tat/physiology
- Genes, tat
- HIV Long Terminal Repeat
- HIV-1/genetics
- Histone Acetyltransferases
- Histones/metabolism
- Humans
- Intracellular Fluid/metabolism
- Models, Biological
- Positive Transcriptional Elongation Factor B
- Promoter Regions, Genetic/genetics
- Protein Processing, Post-Translational
- Protein Serine-Threonine Kinases/metabolism
- RNA Polymerase II/metabolism
- RNA, Messenger/biosynthesis
- RNA, Viral/metabolism
- Receptors, Virus/physiology
- Regulatory Sequences, Nucleic Acid
- Saccharomyces cerevisiae Proteins/metabolism
- Transcriptional Activation
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- Claudio Brigati
- Molecular Oncology Laboratory, National Cancer Research Institute, c/o Centro di Biotecnologie Avanzante, Largo Rosanna Benzi 10, 16132 Genova, Italy
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Reyes CM, Nifosì R, Frankel AD, Kollman PA. Molecular dynamics and binding specificity analysis of the bovine immunodeficiency virus BIV Tat-TAR complex. Biophys J 2001; 80:2833-42. [PMID: 11371457 PMCID: PMC1301468 DOI: 10.1016/s0006-3495(01)76250-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
We have performed molecular dynamics (MD) simulations, with particle-mesh Ewald, explicit waters, and counterions, and binding specificity analyses using combined molecular mechanics and continuum solvent (MM-PBSA) on the bovine immunodeficiency virus (BIV) Tat peptide-TAR RNA complex. The solution structure for the complex was solved independently by Patel and co-workers and Puglisi and co-workers. We investigated the differences in both structures and trajectories, particularly in the formation of the U-A-U base triple, the dynamic flexibility of the Tat peptide, and the interactions at the binding interface. We observed a decrease in RMSD in comparing the final average RNA structures and initial RNA structures of both trajectories, which suggests the convergence of the RNA structures to a MD equilibrated RNA structure. We also calculated the relative binding of different Tat peptide mutants to TAR RNA and found qualitative agreement with experimental studies.
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MESH Headings
- Amino Acid Sequence
- Animals
- Binding Sites
- Cattle
- Computer Simulation
- Gene Products, tat/chemistry
- Gene Products, tat/genetics
- Gene Products, tat/metabolism
- HIV Long Terminal Repeat/genetics
- Hydrogen Bonding
- Immunodeficiency Virus, Bovine/chemistry
- Immunodeficiency Virus, Bovine/genetics
- Models, Molecular
- Molecular Sequence Data
- Mutation/genetics
- Nuclear Magnetic Resonance, Biomolecular
- Nucleic Acid Conformation
- Peptide Fragments/chemistry
- Peptide Fragments/genetics
- Peptide Fragments/metabolism
- Protein Binding
- RNA, Viral/chemistry
- RNA, Viral/genetics
- RNA, Viral/metabolism
- Regulatory Sequences, Nucleic Acid/genetics
- Substrate Specificity
- Thermodynamics
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Affiliation(s)
- C M Reyes
- Department of Pharmaceutical Chemistry, University of California at San Francisco, San Francisco, California 94143, USA
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Caldwell RL, Egan BS, Shepherd VL. HIV-1 Tat represses transcription from the mannose receptor promoter. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:7035-41. [PMID: 11120831 DOI: 10.4049/jimmunol.165.12.7035] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The mannose receptor is expressed on mature macrophages and immature dendritic cells, and functions to mediate phagocytosis of pathogens and capture of Ags for delivery to MHC class II-containing intracellular compartments. It has been previously reported that HIV-1-infected macrophages have reduced functions associated with the mannose receptor, including impaired Pneumocystis carinii phagocytosis and mannosylated albumin uptake. Several HIV-1-derived proteins including the Tat protein have been shown to transcriptionally repress host cell genes. The present study was undertaken to define the role of the HIV-1-derived protein Tat in HIV-mediated mannose receptor down-regulation. Cotransfection of the human macrophage cell line U937 with a Tat expression vector and a mannose receptor promoter-luciferase reporter construct resulted in down-regulation of mannose receptor promoter activity. This repression was targeted to the basal promoter. Expression of either one- or two-exon Tat resulted in decreased promoter activity. The addition of the transactivation response element (TAR) sequence enhanced the Tat-mediated repression. Down-regulation was also seen when transfected cells were treated with exogenously added Tat protein. These results are consistent with a mechanism whereby Tat reduces mannose receptor promoter activity by interfering with the host transcriptional initiation machinery, potentially resulting in decreased levels of surface mannose receptor available for Ag or pathogen capture.
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MESH Headings
- Animals
- Gene Expression Regulation, Viral/immunology
- Gene Products, tat/biosynthesis
- Gene Products, tat/genetics
- Gene Products, tat/pharmacology
- Gene Products, tat/physiology
- Genetic Vectors/immunology
- HIV-1/genetics
- HIV-1/immunology
- Humans
- Lectins, C-Type
- Mannose/metabolism
- Mannose Receptor
- Mannose-Binding Lectins
- Plasmids/immunology
- Promoter Regions, Genetic/immunology
- Rats
- Receptors, Cell Surface/antagonists & inhibitors
- Receptors, Cell Surface/genetics
- Repressor Proteins/biosynthesis
- Repressor Proteins/genetics
- Repressor Proteins/pharmacology
- Repressor Proteins/physiology
- Response Elements/immunology
- Transcription, Genetic/immunology
- Transcriptional Activation/immunology
- U937 Cells
- tat Gene Products, Human Immunodeficiency Virus
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Affiliation(s)
- R L Caldwell
- Departments of. Pathology and Biochemistry, Vanderbilt University. Veterans' Affairs Medical Center, Nashville, TN 37212, USA
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Maury W, Bradley S, Wright B, Hines R. Cell specificity of the transcription-factor repertoire used by a lentivirus: motifs important for expression of equine infectious anemia virus in nonmonocytic cells. Virology 2000; 267:267-78. [PMID: 10662622 DOI: 10.1006/viro.1999.0144] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The equine infectious anemia virus (EIAV) long-terminal repeat (LTR) has been identified as highly variable, both in infected horses and in cell culture. This nucleotide hypervariation is localized to the LTR enhancer region. The EIAV LTR has been implicated in controlling both the cell tropism and virulence of the virus and it is postulated that the enhancer-region hypervariation may be responsible for the LTR effects. Our previous studies have demonstrated that the presence of DNA motifs bound by the ets transcription-factor family member PU.1 are critically important for EIAV expression in equine macrophages. Here we identify and characterize the EIAV LTR enhancer motifs PEA-2, Lvb, Oct, and CRE, that bind to fibroblast nuclear extracts. Three of these four motifs, PEA-2, Oct, and CRE, were determined to be important for expression of the LTR in a fibroblast cell line that supports productive infection of EIAV. These motifs that are important for expression of the LTR in fibroblasts were found to be interdigitated between the PU.1 sites. We hypothesize that the combination of motif interdigitation and cell-specific usage of these motifs may be responsible for the observed EIAV LTR enhancer-region hypervariation.
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MESH Headings
- Animals
- Base Sequence
- Binding Sites
- Cell Line
- Chloramphenicol O-Acetyltransferase/genetics
- Chloramphenicol O-Acetyltransferase/metabolism
- DNA, Viral/chemistry
- DNA, Viral/genetics
- DNA, Viral/metabolism
- Enhancer Elements, Genetic
- Fibroblasts/cytology
- Fibroblasts/metabolism
- Gene Expression Regulation, Viral
- Horses
- Infectious Anemia Virus, Equine/chemistry
- Infectious Anemia Virus, Equine/genetics
- Infectious Anemia Virus, Equine/metabolism
- Molecular Sequence Data
- Mutation
- Nuclear Proteins/metabolism
- Protein Binding
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Repetitive Sequences, Nucleic Acid/genetics
- Sequence Homology, Nucleic Acid
- Transcription Factors/metabolism
- Transcription, Genetic
- Transcriptional Activation
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Affiliation(s)
- W Maury
- Division of Basic Biomedical Sciences, University of South Dakota, Vermillion, South Dakota 57069, USA.
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