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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HIV integrates a DNA copy of its genome into a host cell chromosome in each replication cycle. The essential DNA cleaving and joining chemistry of integration is known, but there is less understanding of the process as it occurs in a cell, where two complex and dynamic macromolecular entities are joined: the viral pre-integration complex and chromatin. Among implicated cellular factors, much recent attention has coalesced around LEDGF/p75, a nuclear protein that may act as a chromatin docking factor or receptor for lentiviral pre-integration complexes. LEDGF/p75 tethers HIV integrase to chromatin, protects it from degradation, and strongly influences the genome-wide pattern of HIV integration. Depleting the protein from cells and/or over-expressing its integrase-binding domain blocks viral replication. Current goals are to establish the underlying mechanisms and to determine whether this knowledge can be exploited for antiviral therapy or for targeting lentiviral vector integration in human gene therapy.
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PMID:Integrase, LEDGF/p75 and HIV replication. 1826 2

Retroviral replication proceeds through a stable proviral DNA intermediate, and numerous host cell factors have been implicated in its formation. In particular, recent results have highlighted an important role for the integrase-interactor lens epithelium-derived growth factor (LEDGF)/p75 in lentiviral integration. Cells engineered to over-express fragments of LEDGF/p75 containing its integrase-binding domain but lacking determinants essential for chromatin association are refractory to HIV-1 infection. Furthermore, both the levels of HIV-1 integration and the genomic distribution of the resultant proviruses are significantly perturbed in cells devoid of endogenous LEDGF/p75 protein. A strong bias towards integration along transcription units is a characteristic feature of lentiviruses. In the absence of LEDGF/p75, HIV-1 in large part loses that preference, displaying concomitant integration surges in the vicinities of CpG islands and gene promoter regions, elements naturally targeted by other types of retroviruses. Together, these findings highlight that LEDGF/p75 is an important albeit not strictly essential cofactor of lentiviral DNA integration, and solidify a role for chromatin-associated LEDGF/p75 as a receptor for lentiviral preintegration complexes. By now one of the best characterized virus-host interactions, the integrase-LEDGF/p75 interface opens a range of opportunities for lentiviral vector targeting for gene therapy applications as well as for the development of novel classes of antiretroviral drugs.
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PMID:The lentiviral integrase binding protein LEDGF/p75 and HIV-1 replication. 1836 82

Small-molecule inhibitors of HIV integrase (HIV IN) have emerged as a promising new class of antivirals for the treatment of HIV/AIDS. The compounds currently approved or in clinical development specifically target HIV DNA integration and were identified using strand-transfer assays targeting the HIV IN/viral DNA complex. The authors have developed a second biochemical assay for identification of HIV integrase inhibitors, targeting the interaction between HIV IN and the cellular cofactor LEDGF/p75. They developed a luminescent proximity assay (AlphaScreen) designed to measure the association of the 80-amino-acid integrase binding domain of LEDGF/p75 with the 163-amino-acid catalytic core domain of HIV IN. This assay proved to be quite robust (with a Z' factor of 0.84 in screening libraries arrayed as orthogonal mixtures) and successfully identified several compounds specific for this protein-protein interaction.
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PMID:Screening for antiviral inhibitors of the HIV integrase-LEDGF/p75 interaction using the AlphaScreen luminescent proximity assay. 1848 Apr 74

Integration of viral-DNA into host chromosome mediated by the viral protein HIV-1 integrase (IN) is an essential step in the HIV-1 life cycle. In this process, Lens epithelium-derived growth factor (LEDGF/p75) is discovered to function as a cellular co-factor for integration. Since LEDGF/p75 plays an important role in HIV integration, disruption of the LEDGF/p75 interaction with IN has provided a special interest for anti-HIV agent discovery. In this work, we reported that a benzoic acid derivative, 4-[(5-bromo-4-{[2,4-dioxo-3-(2-oxo-2-phenylethyl)-1,3-thiazolidin-5-ylidene]methyl}-2-ethoxyphenoxy)methyl]benzoic acid (D77) could potently inhibit the IN-LEDGF/p75 interaction and affect the HIV-1 IN nuclear distribution thus exhibiting antiretroviral activity. Molecular docking with site-directed mutagenesis analysis and surface plasmon resonance (SPR) binding assays has clarified possible binding mode of D77 against HIV-1 integrase. As the firstly discovered small molecular compound targeting HIV-1 integrase interaction with LEDGF/p75, D77 might supply useful structural information for further anti-HIV agent discovery.
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PMID:D77, one benzoic acid derivative, functions as a novel anti-HIV-1 inhibitor targeting the interaction between integrase and cellular LEDGF/p75. 1869 55

Lens epithelium-derived growth factor (LEDGF)/p75 functions as a bimodal tether during lentiviral DNA integration: its C-terminal integrase-binding domain interacts with the viral preintegration complex, whereas the N-terminal PWWP domain can bind to cellular chromatin. The molecular basis for the integrase-LEDGF/p75 interaction is understood, while the mechanism of chromatin binding is unknown. The PWWP domain is homologous to other protein interaction modules that together comprise the Tudor clan. Based on primary amino acid sequence and three-dimensional structural similarities, 24 residues of the LEDGF/p75 PWWP domain were mutagenized to garner essential details of its function during human immunodeficiency virus type 1 (HIV-1) infection. Mutating either Trp-21 or Ala-51, which line the inner wall of a hydrophobic cavity that is common to Tudor clan members, disrupts chromatin binding and virus infectivity. Consistent with a role for chromatin-associated LEDGF/p75 in stimulating integrase activity during infection, recombinant W21A protein is preferentially defective for enhancing integration into chromatinized target DNA in vitro. The A51P mutation corresponds to the S270P change in DNA methyltransferase 3B that causes human immunodeficiency, centromeric instability, and facial anomaly syndrome, revealing a critical role for this amino acid position in the chromatin binding functions of varied PWWP domains. Our results furthermore highlight the requirement for a conserved Glu in the hydrophobic core that mediates interactions between other Tudor clan members and their substrates. This initial systematic mutagenesis of a PWWP domain identifies amino acid residues critical for chromatin binding function and the consequences of their changes on HIV-1 integration and infection.
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PMID:Identification and characterization of PWWP domain residues critical for LEDGF/p75 chromatin binding and human immunodeficiency virus type 1 infectivity. 1879 76

A tetramer model for human immunodeficiency virus type 1 (HIV-1) integrase (IN) with DNA representing long terminal repeat (LTR) termini was previously assembled to predict the IN residues that interact with the LTR termini; these predictions were experimentally verified for nine amino acid residues [Chen, A., Weber, I. T., Harrison, R. W. & Leis, J. (2006). Identification of amino acids in HIV-1 and avian sarcoma virus integrase subsites required for specific recognition of the long terminal repeat ends. J. Biol. Chem., 281, 4173-4182]. In a similar strategy, the unique amino acids found in avian sarcoma virus IN, rather than HIV-1 or Mason-Pfizer monkey virus IN, were substituted into the structurally related positions of HIV-1 IN. Substitutions of six additional residues (Q44, L68, E69, D229, S230, and D253) showed changes in the 3' processing specificity of the enzyme, verifying their predicted interaction with the LTR DNA. The newly identified residues extend interactions along a 16-bp length of the LTR termini and are consistent with known LTR DNA/HIV-1 IN cross-links. The tetramer model for HIV-1 IN with LTR termini was modified to include two IN binding domains for lens-epithelium-derived growth factor/p75. The target DNA was predicted to bind in a surface trench perpendicular to the plane of the LTR DNA binding sites of HIV-1 IN and extending alongside lens-epithelium-derived growth factor. This hypothesis is supported by the in vitro activity phenotype of HIV-1 IN mutant, with a K219S substitution showing loss in strand transfer activity while maintaining 3' processing on an HIV-1 substrate. Mutations at seven other residues reported in the literature have the same phenotype, and all eight residues align along the length of the putative target DNA binding trench.
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PMID:Defining the DNA substrate binding sites on HIV-1 integrase. 1901 51

Retrovirus integrase (IN) integrates the viral linear DNA genome ( approximately 10 kb) into a host chromosome, a step which is essential for viral replication. Integration occurs via a nucleoprotein complex, termed the preintegration complex (PIC). This article focuses on the reconstitution of synaptic complexes from purified components whose molecular properties mirror those of the PIC, including the efficient concerted integration of two ends of linear viral DNA into target DNA. The methods described herein permit the biochemical and biophysical analyses of concerted integration. The methods enable (1) the study of interactions between purified recombinant IN and its viral DNA substrates at the molecular level; (2) the identification and characterization of nucleoprotein complexes involved in the human immunodeficiency virus type-1 (HIV-1) concerted integration pathway; (3) the determination of the multimeric state of IN within these complexes; (4) dissection of the interaction between HIV-1 IN and cellular proteins such as lens epithelium-derived growth factor (LEDGF/p75); (5) the examination of HIV-1 Class II and strand transfer inhibitor resistant IN mutants; (6) the mechanisms associated with strand transfer inhibitors directed against HIV-1 IN that have clinical relevance in the treatment of HIV-1/AIDS.
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PMID:Biochemical and biophysical analyses of concerted (U5/U3) integration. 1904 78

One of the major obstacles to pursue the discovery of small molecule inhibitors targeting protein-protein interactions is the flat nature of their interface. X-Ray structures have indeed shown that a large part of the interaction area is buried with atoms closely packed together, implying a lack of available cavities for small molecule binding. Yet, it has become clear that some protein-protein interfaces have a well-defined compact area, commonly referred to as a hot spot, that plays a major role in the affinity of the interaction. These hot spots define potential targets for the development of small molecule protein-protein interaction inhibitors (SMPPIIs). In this review we discuss the interactions between viral and host proteins that have the potential for the future development of SMPPIIs. In light of the current anti-HIV therapy a short overview of protein-protein interactions that may serve as targets for novel drugs is provided. Our hypothesis will exemplify and discuss the interaction between HIV-1 integrase and its cellular cofactor LEDGF/p75, which, as evidenced by crystallography and site directed mutagenesis, displays favourable properties needed for the development of interaction inhibitors.
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PMID:In search of small molecules blocking interactions between HIV proteins and intracellular cofactors. 1908 27

Lens epithelium derived growth factor (LEDGF), also known as PC4 and SFRS1 interacting protein 1 (PSIP1) and transcriptional co-activator p75, is the cellular binding partner of lentiviral integrase (IN) proteins. LEDGF accounts for the characteristic propensity of Lentivirus to integrate within active transcription units and is required for efficient viral replication. We now present a crystal structure containing the N-terminal and catalytic core domains (NTD and CCD) of HIV-2 IN in complex with the IN binding domain (IBD) of LEDGF. The structure extends the known IN-LEDGF interface, elucidating primarily charge-charge interactions between the NTD of IN and the IBD. A constellation of acidic residues on the NTD is characteristic of lentiviral INs, and mutations of the positively charged residues on the IBD severely affect interaction with all lentiviral INs tested. We show that the novel NTD-IBD contacts are critical for stimulation of concerted lentiviral DNA integration by LEDGF in vitro and for its function during the early steps of HIV-1 replication. Furthermore, the new structural details enabled us to engineer a mutant of HIV-1 IN that primarily functions only when presented with a complementary LEDGF mutant. These findings provide structural basis for the high affinity lentiviral IN-LEDGF interaction and pave the way for development of LEDGF-based targeting technologies for gene therapy.
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PMID:A novel co-crystal structure affords the design of gain-of-function lentiviral integrase mutants in the presence of modified PSIP1/LEDGF/p75. 1913 83

Integration of the human immunodeficiency virus (HIV-1) cDNA into the human genome is catalysed by integrase. Several studies have shown the importance of the interaction of cellular cofactors with integrase for viral integration and infectivity. In this study, we produced a stable and functional complex between the wild-type full-length integrase (IN) and the cellular cofactor LEDGF/p75 that shows enhanced in vitro integration activity compared with the integrase alone. Mass spectrometry analysis and the fitting of known atomic structures in cryo negatively stain electron microscopy (EM) maps revealed that the functional unit comprises two asymmetric integrase dimers and two LEDGF/p75 molecules. In the presence of DNA, EM revealed the DNA-binding sites and indicated that, in each asymmetric dimer, one integrase molecule performs the catalytic reaction, whereas the other one positions the viral DNA in the active site of the opposite dimer. The positions of the target and viral DNAs for the 3' processing and integration reaction shed light on the integration mechanism, a process with wide implications for the understanding of viral-induced pathologies.
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PMID:Structural basis for HIV-1 DNA integration in the human genome, role of the LEDGF/P75 cofactor. 1922 93


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