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

The protease encoded by the human immunodeficiency virus-1 (HIV-1) is essential for processing viral polyproteins which contain the enzymes and structural proteins required for the infectious virus. It was previously found that cupric chloride, in the presence of dithiothreitol or ascorbic acid, could inhibit the HIV-1 protease. It was suggested that a Cu1+ chelate was the moiety responsible for inhibition of the protease. This hypothesis has now been investigated directly by utilizing the stable Cu1+ chelate, bathocuproine disulfonic acid Cu1+ (BCDS-Cu1+). BCDS-Cu1+ inhibited the HIV-1 wild type protease as well as a mutant HIV-1 protease lacking cysteines. BCDS-Cu1+ was a competitive inhibitor of the mutant HIV-1 protease with an apparent Ki of 1 microM. Replication of HIV-1 in human lymphocytes and the cytotoxic effect of HIV-1 in CEM cells was inhibited by micromolar BCDS-Cu1+. Inhibition of the protease and of HIV replication by BCDS-Cu1+ was dependent on the presence of Cu1+ as BCDS alone was ineffective. EDTA blocked the inhibition of the protease by Cu1+ but was unable to block inhibition of the protease by BCDS-Cu1+, indicating that the Cu1+ complex was the inhibitory agent. The apparent IC50 for BCDS-Cu1+ on the inhibition of replication by primary isolates of HIV-1 was 5 microM. However, BCDS-Cu1+ did not affect polyprotein processing in an H9 cell line chronically infected with HIV-1, indicating that BCDS-Cu1+ acts by yet another mechanism to block HIV infection. Other possible targets for BCDS-Cu1+ include inhibition of viral adsorption and/or inhibition of the HIV-1 integrase.
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PMID:Inhibition of the human immunodeficiency virus-1 protease and human immunodeficiency virus-1 replication by bathocuproine disulfonic acid Cu1+. 757 66

Efficient replication of HIV-1 requires establishment of the proviral state, i.e., the integration of a DNA copy of the viral genome, synthesized by reverse transcriptase, into a chromosome of the host cell. Integration is catalyzed by the viral integrase protein. We have previously reported that phenolic moieties in compounds such as napthoquinones, flavones, caffeic acid phenethyl ester (CAPE), and curcumin confer inhibitory activity against HIV-1 integrase. We have extended these findings by examining the effects of tryphostins, tyrosine kinase inhibitors. The catalytic activities of HIV-1 integrase and the formation of enzyme-DNA complexes using photocross-linking were examined. Both steps of the integration reaction, 3'-processing and strand transfer, were inhibited by tyrphostins at micromolar concentrations. The DNA binding activity of integrase was inhibited at higher concentrations of tryphostins. Disintegration, an apparent reversal of the strand transfer reaction, catalyzed by an integrase mutant lacking the N-terminal zinc finger and C-terminal DNA binding domains is also inhibited by tyrphostins, indicating that the binding site for these compounds resides in the central catalytic core of HIV-1 integrase. Binding of tyrphostins at or near the integrase catalytic site was also suggested by experiments showing a global inhibition of the choice of attacking nucleophile in the 3'-processing reaction. None of the tryphostins tested inhibited eukaryotic topoisomerase I, even at 100 microM, suggesting selectivity for integrase inhibition. Molecular-modeling studies have revealed that, after energy minimization, several tyrphostins may adopt folded conformations. The similarity of the tyrphostin family to other families of inhibitors is discussed. Tyrphostins may provide lead compounds for development of novel antiviral agents for the treatment of acquired immunodeficiency syndrome based upon inhibition of HIV-1 integrase.
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PMID:Effects of tyrphostins, protein kinase inhibitors, on human immunodeficiency virus type 1 integrase. 757 25

The karyophilic properties of the viral matrix (MA) protein govern HIV nuclear import in nondividing cells such as macrophages. A critical regulator of this process is the C-terminal tyrosine phosphorylation of MA during virus maturation. Here, we reveal the mechanism of this phenomenon, by demonstrating that tyrosine phosphorylation induces the binding of MA to integrase (IN). This leads to the incorporation of MA molecules into virus cores, and subsequently into uncoated viral nucleoprotein complexes. A direct interaction between tyrosine-phosphorylated MA and the central domain of IN can be demonstrated in vitro. It is blocked by phosphotyrosine, indicating that IN recognizes the phosphorylated C-terminal residue of MA. These results explain how the karyophilic potential of MA is conferred to the HIV nucleoprotein complex.
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PMID:HIV nuclear import is governed by the phosphotyrosine-mediated binding of matrix to the core domain of integrase. 758 60

The newly discovered Ini1 cellular protein binds HIV-1 integrase and is part of a protein complex thought to alter nucleosomal structure; such alterations may influence the selection of sites for HIV-1 DNA integration.
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PMID:HIV integration. Ini1 for integration? 762 49

The crystal structure of the core domain of bacteriophage Mu transposase, MuA, has been determined at 2.4 A resolution. The first of two subdomains contains the active site and, despite very limited sequence homology, exhibits a striking similarity to the core domain of HIV-1 integrase, which carries out a similar set of biochemical reactions. It also exhibits more limited similarity to other nucleases, RNase H and RuvC. The second, a beta barrel, connects to the first subdomain through several contacts. Three independent determinations of the monomer structure from two crystal forms all show the active site held in a similar, apparently inactive configuration. The enzymatic activity of MuA is known to be activated by formation of a DNA-bound tetramer of the protein. We propose that the connections between the two subdomains may be involved in the cross-talk between the active site and the other domains of the transposase that controls the activity of the protein.
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PMID:Structure of the bacteriophage Mu transposase core: a common structural motif for DNA transposition and retroviral integration. 762 12

The solution structure of the DNA binding domain of HIV-1 integrase (residues 220-270) has been determined by multidimensional NMR spectroscopy. The protein is a dimer in solution, and each subunit is composed of a five-stranded beta-barrel with a topology very similar to that of the SH3 domain. The dimer is formed by a stacked beta-interface comprising strands 2, 3, and 4, with the two triple-stranded antiparallel beta-sheets, one from each subunit, oriented antiparallel to each other. One surface of the dimer, bounded by the loop between strands beta 1 and beta 2, forms a saddle-shaped groove with dimensions of approximately 24 x 23 x 12 A in cross section. Lys264, which has been shown from mutational data to be involved in DNA binding, protrudes from this surface, implicating the saddle-shaped groove as the potential DNA binding site.
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PMID:Solution structure of the DNA binding domain of HIV-1 integrase. 763 83

The integrase protein from human immunodeficiency virus type 1 (HIV-1) has generally been reported to require Mn2+ for efficient in vitro activity. We have reexamined the divalent metal ion requirements of HIV-1 integrase and find that the protein is capable of promoting efficient 3' processing and DNA strand transfer with either Mn2+ or Mg2+. The metal ion preference depended upon the reaction conditions. HIV-1 integrase displayed significantly less nonspecific nuclease activity in reaction mixtures containing Mg2+ than it did under the previously described reaction conditions with mixtures containing Mn2+.
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PMID:Efficient magnesium-dependent human immunodeficiency virus type 1 integrase activity. 763 39

Human immunodeficiency virus type 1 integrase (HIV-1 IN) catalyzes the integration of HIV-1 DNA into the host chromosome. In vitro reactions with endogenous viral DNA require Mg2+ as the metal cofactor, whereas in vitro studies performed with short oligonucleotide substrates utilize Mn2+. In this study, we report that the donor processing activity of HIV-1 IN alters depending on the structure and length of the oligonucleotide substrates. Increases in the length of the substrate cause alterations in the efficiency of Mg(2+)-dependent donor processing activity, thereby reconciling this discrepancy between the in vivo and in vitro HIV-1 IN mediated reactions. We have also found that the 3'-processing activity of HIV-IN is responsible for cleaving the junction between the viral and target sequences of the recombination intermediate. Its mechanism differs from the previously described disintegration reaction in that the donor strands are regenerated without a joining reaction of the target strands. Kinetic studies of 3'-processing activity suggest that the kcat (0.24/h) is very low. This implies that HIV-1 IN remains as a complex with the processed DNA prior to the strand transfer reaction.
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PMID:Characterization of Mg(2+)-dependent 3'-processing activity for human immunodeficiency virus type 1 integrase in vitro: real-time kinetic studies using fluorescence resonance energy transfer. 764 Feb 75

Human immunodeficiency virus type 1 integrase (HIV-IN) is an enzyme essential for the integration of viral DNA into the host chromosome, a process that is an attractive target for drug development. In vitro assays have been developed to study both components of the integration process, the 3'-processing and strand transfer reactions. However, major discrepancies between results obtained from in vivo and in vitro events raise concerns as to the biological relevance of activities observed in vitro. These discrepancies include the size of the substrate and the nature of the divalent cation used. In this study, we characterized activities of HIV-IN with oligonucleotide substrates varying in length. Our previous studies indicate that the preferred cation in vitro for 3'-processing is altered from Mn2+ to Mg2+ by increasing the length of the oligonucleotide substrate. This study demonstrates that HIV-IN efficiently catalyzes Mg(2+)-dependent 3'-processing while repressing the strand transfer reaction. Substrate competition studies indicate that longer substrates preferentially bind to the viral DNA binding site of the integrase, whereas the shorter substrate has much less specificity. In addition, the shorter substrate requires a higher concentration of Mg2+, indicating that there is an alteration in the metal binding affinity associated with the varying substrates. Our results show that substrate-length-dependent differential activities are due to differences in the divalent metal binding and DNA binding affinities associated with the different substrates. These results suggest that the structure of the viral DNA is an important factor in differentiating the donor and target substrates.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Substrate-length-dependent activities of human immunodeficiency virus type 1 integrase in vitro: differential DNA binding affinities associated with different lengths of substrates. 764 Feb 76

We have examined the activities of HIV-1 integrase on substrates containing mismatches, composed of deoxyuridine at different positions in either the processed or nonprocessed strand of viral DNA, within and near the conserved CA dinucleotide of the U5 end of the HIV-1 LTR. Substitution in the processed strand of either the C or A of the CA dinucleotide or of the G 5' to the CA reduced strand transfer six-, three- and seven-fold respectively. 3'-processing was also reduced by substitution at the GC but not at the A. Substitution in the nonprocessed strand of the G nucleotide at the processing site abolished strand transfer while substitution of the T had no effect. DNA binding of HIV-1 integrase was not affected by deoxyuridine substitutions. Deoxyuridine substitution outside the trinucleotide remained compatible with enzyme activity. Enzymatically generated abasic sites were created at each mismatch to determine the effect of a missing base on integrase activity. Consistent with the deoxyuridine mismatch observations, 3'-processing and strand transfer were abolished when the abasic site was substituted for either of the nucleotides of the GCA trinucleotide. Integrase was, however, able to tolerate mismatches within this trinucleotide during the disintegration reaction. Taken together, these results suggest that base-mismatched or base-deleted substrates, which can be created by the proofreading-deficient HIV-1 RT, can be tolerated by HIV-1 integrase when located outside of the GCA trinucleotide at the U5 end of the LTR.
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PMID:Processing of deoxyuridine mismatches and abasic sites by human immunodeficiency virus type-1 integrase. 765 8


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