1
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Goswami D, Tuske S, Pascal BD, Bauman JD, Patel D, Arnold E, Griffin PR. Differential isotopic enrichment to facilitate characterization of asymmetric multimeric proteins using hydrogen/deuterium exchange mass spectrometry. Anal Chem 2015; 87:4015-4022. [PMID: 25763479 DOI: 10.1021/acs.analchem.5b00372] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Hydrogen/deuterium exchange (HDX) coupled to mass spectrometry has emerged as a powerful tool for analyzing the conformational dynamics of protein-ligand and protein-protein interactions. Recent advances in instrumentation and methodology have expanded the utility of HDX for the analysis of large and complex proteins; however, asymmetric dimers with shared amino acid sequence present a unique challenge for HDX because assignment of peptides with identical sequence to their subunit of origin remains ambiguous. Here we report the use of differential isotopic labeling to facilitate HDX analysis of multimers using HIV-1 reverse transcriptase (RT) as a model. RT is an asymmetric heterodimer of 51 kDa (p51) and 66 kDa (p66) subunits. The first 440 residues of p51 and p66 are identical. In this study differentially labeled RT was reconstituted from isotopically enriched ((15)N-labeled) p51 and unlabeled p66. To enable detection of (15)N-deuterated RT peptides, the software HDX Workbench was modified to follow a 100% (15)N model. Our results demonstrated that (15)N enrichment of p51 did not affect its conformational dynamics compared to unlabeled p51, but (15)N-labeled p51 did show different conformational dynamics than p66 in the RT heterodimer. Differential HDX-MS of isotopically labeled RT in the presence of the non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz (EFV) showed subunit-specific perturbation in the rate of HDX consistent with previously published results and the RT-EFV cocrystal structure.
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Affiliation(s)
- Devrishi Goswami
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458.USA
| | - Steve Tuske
- Center for Advanced Biotechnology and Medicine, and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Bruce D Pascal
- Informatics Core, The Scripps Research Institute, Jupiter, FL 33458.USA
| | - Joseph D Bauman
- Center for Advanced Biotechnology and Medicine, and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Disha Patel
- Center for Advanced Biotechnology and Medicine, and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Eddy Arnold
- Center for Advanced Biotechnology and Medicine, and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Patrick R Griffin
- Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458.USA
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2
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Purification of untagged HIV-1 reverse transcriptase by affinity chromatography. Protein Expr Purif 2010; 71:231-9. [DOI: 10.1016/j.pep.2010.01.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Revised: 12/31/2009] [Accepted: 01/04/2010] [Indexed: 11/18/2022]
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3
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Bakhanashvili M, Rahav G. The incorporation of nucleoside analogs by human immunodeficiency virus type 1 reverse transcriptase decreases in the presence of polyamines. FEBS Lett 2006; 580:5363-70. [PMID: 16989821 DOI: 10.1016/j.febslet.2006.08.074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 07/30/2006] [Accepted: 08/17/2006] [Indexed: 11/24/2022]
Abstract
Nucleoside analogs (NAs) are an important class of anti-retroviral compounds used against human immunodeficiency virus (HIV). We have analyzed the potential effect of polyamines on the incorporation of NAs during DNA synthesis by HIV type-1 (HIV-1) reverse transcriptase (RT). The polyamines exert the ability to decrease the incorporation of various dideoxynucleoside triphosphates (ddATP, ddTTP or ddCTP) with both RNA/DNA and DNA/DNA substrates in the following order: spermine>spermidine>putrescine. The reduction is a sequence-independent effect, taking place at different sequence context. The results suggest that polyamines might affect the inhibition of reverse transcription by nucleoside analogs HIV-1 RT directed.
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Affiliation(s)
- Mary Bakhanashvili
- Infectious Diseases Unit, Chaim Sheba Medical Center, Tel Hashomer, 52621 Ramat-Gan, Israel.
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4
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Meyer PR, Smith AJ, Matsuura SE, Scott WA. Chain-terminating dinucleoside tetraphosphates are substrates for DNA polymerization by human immunodeficiency virus type 1 reverse transcriptase with increased activity against thymidine analogue-resistant mutants. Antimicrob Agents Chemother 2006; 50:3607-14. [PMID: 16940076 PMCID: PMC1635194 DOI: 10.1128/aac.00537-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Nucleoside reverse transcriptase inhibitors are an important class of drugs for treatment of human immunodeficiency virus type 1 (HIV-1) infection. Resistance to these drugs is often the result of mutations that increase the transfer of chain-terminating nucleotides from blocked DNA termini to a nucleoside triphosphate acceptor, resulting in the generation of an unblocked DNA chain and synthesis of a dinucleoside polyphosphate containing the chain-terminating deoxynucleoside triphosphate analogue. We have synthesized and purified several dinucleoside tetraphosphates (ddAp4ddA, ddCp4ddC, ddGp4ddG, ddTp4ddT, Ap4ddG, 2'(3')-O-(N-methylanthraniloyl)-Ap4ddG, and AppNHppddG) and show that these compounds can serve as substrates for DNA chain elongation and termination resulting in inhibition of DNA synthesis. Thymidine analogue-resistant mutants of reverse transcriptase are up to 120-fold more sensitive to inhibition by these compounds than is wild-type enzyme. Drugs based on the dinucleoside tetraphosphate structure could delay or prevent the emergence of mutants with enhanced primer unblocking activity. In addition, such drugs could suppress the resistance phenotype of mutant HIV-1 that is present in individuals infected with resistant virus.
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Affiliation(s)
- Peter R Meyer
- Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, P.O. Box 016129, Miami, FL 33101-6129, USA
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5
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Oz Gleenberg I, Avidan O, Goldgur Y, Herschhorn A, Hizi A. Peptides derived from the reverse transcriptase of human immunodeficiency virus type 1 as novel inhibitors of the viral integrase. J Biol Chem 2005; 280:21987-96. [PMID: 15790559 DOI: 10.1074/jbc.m414679200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent studies have shown that the integrase (IN) of HIV-1 is inhibited in vitro by HIV-1 reverse transcriptase (RT). We further investigated the specific protein sequences of RT that were involved in this inhibition by screening a complete library of RT-derived peptides for their inhibition of IN activities. Two 20-residue peptides, peptide 4286, derived from the RT DNA polymerase domain, and the one designated 4321, from the RT ribonuclease H domain, inhibit the enzymatic activities of IN in vitro. The former peptide inhibits all three IN-associated activities (3'-end processing, strand transfer, and disintegration), whereas the latter one inhibits primarily the first two functions. We showed the importance of the sequences and peptide length for the effective inhibition of IN activities. Binding assays of the peptides to IN (with no DNA substrate present) indicated that the two inhibitory peptides (as well as several non-inhibitory peptides) interact directly with IN. Moreover, the isolated catalytic core domain of IN also interacted directly with the two inhibitory peptides. Nevertheless, only peptide 4286 can inhibit the disintegration activity associated with the IN core domain, because this activity is the only one exhibited by this domain. This result was expected from the lack of inhibition of disintegration of full-length IN by peptide 4321. The data and the three-dimensional models presented suggested that the inhibition resulted from steric hindrance of the catalytic domain of IN. This information can substantially facilitate the development of novel drugs against HIV INs and thus contribute to the fight against AIDS.
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Affiliation(s)
- Iris Oz Gleenberg
- Department of Cell and Developmental Biology, The Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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6
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Bakhanashvili M, Novitsky E, Levy I, Rahav G. The fidelity of DNA synthesis by human immunodeficiency virus type 1 reverse transcriptase increases in the presence of polyamines. FEBS Lett 2005; 579:1435-40. [PMID: 15733853 DOI: 10.1016/j.febslet.2005.01.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2004] [Revised: 12/21/2004] [Accepted: 01/04/2005] [Indexed: 02/02/2023]
Abstract
The high error rates characteristic of human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT) are a presumptive source of the viral hypervariability that substantially affect viral pathogenesis and resistance to drug therapy. We have analyzed the potential role of polyamines in the fidelity of DNA synthesis by HIV-1 RT. The current study suggest that polyamines tested has the potential to be "antimutator". The polyamines exert the ability to reduce the misincorporation and mispair extension with both RNA/DNA and DNA/DNA template-primers in the following order: spermine > spermidine > putrescine. In view of the significance of mutations of HIV, the possible roles of polyamines in the accuracy of DNA synthesis could be of particular importance; polyamines may affect the mutation rate of the virus.
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Affiliation(s)
- Mary Bakhanashvili
- Infectious Diseases Unit, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel.
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7
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Hou EW, Prasad R, Beard WA, Wilson SH. High-level expression and purification of untagged and histidine-tagged HIV-1 reverse transcriptase. Protein Expr Purif 2004; 34:75-86. [PMID: 14766302 DOI: 10.1016/j.pep.2003.10.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2003] [Revised: 10/31/2003] [Indexed: 11/29/2022]
Abstract
We have devised simplified protocols to purify large quantities of histidine-tagged (His-tagged) and untagged heterodimeric forms of human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT). Here, we report the optimization of overexpression and purification of heterodimeric RT expressed in Escherichia coli. The coding sequences of p66 and p51 subunits of RT were amplified using PCR from HXB2 HIV-1 and cloned into a bacterial expression system. The resulting expression plasmids for the RT subunits, pET-RT66 and pET-RT51, were under a strong T7/lac promoter that is induced by isopropyl-beta-d-thiogalactopyranoside. Purification of heterodimeric forms of RT was facilitated by high-level expression of these subunits that represented approximately 30-40% of total cell protein. For purification of the His-tagged heterodimeric RT, cell pellet from cells expressing the untagged p66 subunit was mixed in excess with a cell pellet expressing tagged p51. For untagged heterodimeric RT, the pellet from cells expressing p51 was mixed in excess with pellet expressing p66. Subunit dimerization occurred during cell lysis. During the subsequent chromatography steps, stable p66/p51 heterodimer was purified to homogeneity. The heterodimeric nature of the final preparations of RT was confirmed by analytical gel filtration, mass spectrometry, and denaturing gel electrophoresis. Further, the sensitivity of these enzyme preparations to AZTTP indicated that the histidine tag had no effect on nucleoside inhibitor binding, nucleotide binding or insertion, or DNA binding. The application of these expression/purification methodologies represents a useful method to purify large quantities of heterodimeric RT for structural investigations and provides an efficient protocol to produce subunit-specific amino acid alterations necessary for unambiguous structure/function investigations.
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Affiliation(s)
- Esther W Hou
- Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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8
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Meyer PR, Smith AJ, Matsuura SE, Scott WA. Effects of primer-template sequence on ATP-dependent removal of chain-terminating nucleotide analogues by HIV-1 reverse transcriptase. J Biol Chem 2004; 279:45389-98. [PMID: 15308646 DOI: 10.1074/jbc.m405072200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
HIV-1 reverse transcriptase can remove chain terminators from blocked DNA ends through a nucleotide-dependent mechanism. We show that the catalytic efficiency of the removal reaction can vary several hundred-fold in different sequence contexts and is most strongly affected by the nature of the base pair at the 3'-primer terminus and the six base pairs upstream of it. Similar effects of the upstream sequence were observed with primer-templates terminated with 2',3'-dideoxy-AMP, 2',3'-dideoxy-CMP, or 2',3'-dideoxy-GMP. However, the removal of 2',3'-dideoxy-TMP or 3'-azido-2',3'-dideoxy-TMP was much less influenced by upstream primer-template sequence, and the rate of excision of these thymidylate analogues was greater than or equal to that of the other chain-terminating residues in each sequence context tested. These results strongly indicate that the primer terminus and adjacent upstream base pairs interact with reverse transcriptase in a sequence-dependent manner that affects the removal reaction. We conclude that primer-template sequence context is a major factor to consider when evaluating the removal of different chain terminators by HIV-1 reverse transcriptase.
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Affiliation(s)
- Peter R Meyer
- Department of Biochemistry and Molecular Biology, University of Miami School of Medicine, Miami, Florida 33136-1015, USA
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9
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Bakhanashvili M, Novitsky E, Lilling G, Rahav G. P53 in cytoplasm may enhance the accuracy of DNA synthesis by human immunodeficiency virus type 1 reverse transcriptase. Oncogene 2004; 23:6890-9. [PMID: 15286711 DOI: 10.1038/sj.onc.1207846] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The tumor suppressor protein p53 displays 3' --> 5' exonuclease activity and can provide a proofreading function for DNA polymerases. Reverse transcriptase (RT) of human immunodeficiency virus (HIV)-1 is responsible for the conversion of the viral genomic ssRNA into the proviral DNA in the cytoplasm. The relatively low fidelity of HIV-1 RT was implicated as a dominant factor contributing to the genetic variability of the virus. The lack of intrinsic 3' --> 5' exonuclease activity, the formation of 3'-mispaired DNA and the subsequent extension of this DNA were shown to be determinants for the low fidelity of HIV-1 RT. It was of interest to analyse whether the cytoplasmic proteins may affect the accuracy of DNA synthesis by RT. We investigated the fidelity of DNA synthesis by HIV-1 RT with and without exonucleolytic proofreading provided by cytoplasmic fraction of LCC2 cells expressing high level of wild-type functional p53. Two basic features related to fidelity of DNA synthesis were studied: the misinsertion and mispair extension. The misincorporation of noncomplementary deoxynucleotides into nascent DNA and subsequent mispair extension by HIV-1 RT were substantially decreased in the presence of cytoplasmic fraction of LCC2 cells with both RNA/DNA and DNA/DNA template-primers with the same target sequence. The mispair extension frequencies obtained with the HIV-1 RT in the presence of cytoplasmic fraction of LCC2 cells were significantly lower (about 2.8-15-fold) than those detected with the purified enzyme. In addition, the productive interaction between polymerization (by HIV-1 RT) and exonuclease (by p53 in cytoplasm) activities was observed; p53 preferentially hydrolyses mispaired 3'-termini, permitting subsequent extension of the correctly paired 3'-terminus by HIV-1 RT. The data suggest that p53 in cytoplasm may affect the accuracy of DNA replication and the mutation spectra of HIV-1 RT by acting as an external proofreader. Furthermore, the decrease in error-prone DNA synthesis with RT in the presence of external exonuclease, provided by cytoplasmic p53, may partially account for lower mutation rate of HIV-1 observed in vivo.
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Affiliation(s)
- Mary Bakhanashvili
- Infectious Diseases Unit, Sheba Medical Center, Tel Hashomer 52621, Israel.
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10
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Loya S, Rudi A, Kashman Y, Hizi A. Mode of inhibition of HIV-1 reverse transcriptase by polyacetylenetriol, a novel inhibitor of RNA- and DNA-directed DNA polymerases. Biochem J 2002; 362:685-92. [PMID: 11879196 PMCID: PMC1222433 DOI: 10.1042/0264-6021:3620685] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Polyacetylenetriol (PAT), a natural marine product from the Mediterranean sea sponge Petrosia sp., was found to be a novel general potent inhibitor of DNA polymerases. It inhibits equally well the RNA- and DNA-dependent DNA polymerase activities of retroviral reverse transcriptases (RTs) (i.e. of HIV, murine leukaemia virus and mouse mammary tumour virus) as well as cellular DNA polymerases (i.e. DNA polymerases alpha and beta and Escherichia coli polymerase I). A study of the mode and mechanism of the polymerase inhibition by PAT has been conducted with HIV-1 RT. PAT was shown to be a reversible non-competitive inhibitor. PAT binds RT independently and at a site different from that of the primer-template and dNTP substrates with high affinity (K(i)=0.51 microM and K(i)=0.53 microM with dTTP and with dGTP as the variable substrates respectively). Blocking the polar hydroxy groups of PAT has only a marginal effect on the inhibitory capacity, thus hydrophobic interactions are likely to play a major role in inhibiting RT. Preincubation of RT with the primer-template substrate prior to the interaction with PAT reduces substantially the inhibition capacity, probably by preventing these contacts. PAT does not interfere with the first step of polymerization, the binding of RT to DNA, nor does the inhibitor interfere with the binding of dNTP to RT/DNA complex, as evident from the steady-state kinetic study, whereby K(m) remains unchanged. We assume, therefore, that PAT interferes with subsequent catalytic steps of DNA polymerization. The inhibitor may alter the optimal stereochemistry of the polymerase active site relative to the primer terminus, bound dNTP and the metal ions that are crucial for efficient catalysis or, alternatively, may interfere with the thumb sub-domain movement and, thus, with the translocation of the primer-template following nucleotide incorporation.
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Affiliation(s)
- Shoshana Loya
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
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11
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Bakhanashvili M. p53 enhances the fidelity of DNA synthesis by human immunodeficiency virus type 1 reverse transcriptase. Oncogene 2001; 20:7635-44. [PMID: 11753641 DOI: 10.1038/sj.onc.1204956] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2001] [Revised: 08/31/2001] [Accepted: 09/04/2001] [Indexed: 11/08/2022]
Abstract
The tumor suppressor protein p53 plays a critical role in the maintenance of genetic integrity. p53 possesses 3'-->5' exonuclease activity, however, the significance of this function in DNA replication process remains elusive. It was suggested that 3'-->5' exonuclease activity of p53 may provide a proofreading function for DNA polymerases. In order to better understand the significance of this activity, the purified wild-type recombinant p53 was further evaluated for substrate specificity and for contribution to the accuracy of DNA synthesis. p53-associated 3'-->5' exonuclease displays 3' terminal nucleotide excision from RNA/DNA template-primer using ribosomal RNA as a template. The data demonstrate that p53 is highly efficient in removing a terminal mispair. Analysis of mispair excision opposite the template adenine residue shows that p53 catalyzes 3' terminal mismatch excision with a specificity of A : G>A : A>A : C. Hence, the observed specificity of mismatch excision indicates that p53 exonucleolytic proofreading preferentially repairs transversion mutations. The influence of the p53 on the accuracy of DNA synthesis was determined with exonuclease-deficient human immunodeficiency virus-1 (HIV-1) reverse transcriptase (RT), a key enzyme in the life cycle of the virus, that contributes significantly to the low accuracy of proviral DNA synthesis. Using an in vitro biochemical assay with recombinant purified HIV-1 RT, p53 and defined RNA/DNA or DNA/DNA template-primers, two basic features related to fidelity of DNA synthesis were studied: the misinsertion and mispair extension. The misincorporation of non-complementary deoxynucleotides into nascent DNA and subsequent mispair extension by HIV-1 RT were substantially decreased in the presence of p53 with both RNA/DNA and DNA/DNA template-primers. In addition, the productive interaction between polymerization (by HIV-1 RT) and exonuclease (by p53) activities was observed; p53 preferentially hydrolyzes mispaired 3'-termini, permitting subsequent extension of the correctly paired 3'-terminus by HIV-1 RT. Taken together the data demonstrate that preferential excision of mismatched nucleotides by 3'-->5' exonuclease activity of wild-type p53 enhances the fidelity of DNA synthesis by HIV-1 RT in vitro, thus providing a biochemical mechanism to reduce mutations caused by incorporation of mismatched nucleotides. The fact that p53 is reactive with both RNA/DNA and DNA/DNA template-primers raises an interesting possibility of the existence of functional cooperation between p53 and HIV-1 RT in cytoplasm during the reverse transcription process, which may be important for maintaining HIV genomic integrity.
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Affiliation(s)
- M Bakhanashvili
- Infectious Diseases Unit, Chaim Sheba Medical Center, Tel Hashomer 52621, Israel.
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12
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Yu F, Joshi SM, Ma YM, Kingston RL, Simon MN, Vogt VM. Characterization of Rous sarcoma virus Gag particles assembled in vitro. J Virol 2001; 75:2753-64. [PMID: 11222698 PMCID: PMC115899 DOI: 10.1128/jvi.75.6.2753-2764.2001] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Purified retrovirus Gag proteins or Gag protein fragments are able to assemble into virus-like particles (VLPs) in vitro in the presence of RNA. We have examined the role of nucleic acid and of the NC domain in assembly of VLPs from a Rous sarcoma virus (RSV) Gag protein and have characterized these VLPs using transmission electron microscopy (TEM), scanning TEM (STEM), and cryoelectron microscopy (cryo-EM). RNAs of diverse sizes, single-stranded DNA oligonucleotides as small as 22 nucleotides, double-stranded DNA, and heparin all promoted efficient assembly. The percentages of nucleic acid by mass, in the VLPs varied from 5 to 8%. The mean mass of VLPs, as determined by STEM, was 6.5 x 10(7) Da for both RNA-containing and DNA oligonucleotide-containing particles, corresponding to a stoichiometry of about 1,200 protein molecules per VLP, slightly lower than the 1,500 Gag molecules estimated previously for infectious RSV. By cryo-EM, the VLPs showed the characteristic morphology of immature retroviruses, with discernible regions of high density corresponding to the two domains of the CA protein. In spherically averaged density distributions, the mean radial distance to the density corresponding to the C-terminal domain of CA was 33 nm, considerably smaller than that of equivalent human immunodeficiency virus type 1 particles. Deletions of the distal portion of NC, including the second Zn-binding motif, had little effect on assembly, but deletions including the charged residues between the two Zn-binding motifs abrogated assembly. Mutation of the cysteine and histidine residues in the first Zn-binding motif to alanine did not affect assembly, but mutation of the basic residues between the two Zn-binding motifs, or of the basic residues in the N-terminal portion of NC, abrogated assembly. Together, these findings establish VLPs as a good model for immature virions and establish a foundation for dissection of the interactions that lead to assembly.
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Affiliation(s)
- F Yu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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13
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14
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Perach M, Hizi A. Catalytic features of the recombinant reverse transcriptase of bovine leukemia virus expressed in bacteria. Virology 1999; 259:176-89. [PMID: 10364502 DOI: 10.1006/viro.1999.9761] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We have expressed the recombinant reverse transcriptase (RT) of bovine leukemia virus (BLV) in bacteria. The gene encoding the RT was designed to start at its 5' end next to the last codon of the mature viral protease, namely the amino terminus of the RT matches the last 26 codons of the pro gene and is coded for by the pro reading frame. The RT sequence extends into the pol gene, utilizing the pol reading frame after overcoming the stop codon by adding an extra nucleotide (thus imitating the naturally occurring frameshift event). Hence we have generated a transframe polypeptide that is a 584-residues-long protein (see Rice, Stephens, Burny, and Gilden (1985) Virology 142, 357-377). This protein was partially purified after adding a six-histidine tag and studied biochemically testing a variety of parameters. The enzyme exhibits all activities typical of RTs, i.e., both RNA- and DNA-dependent DNA polymerase as well as a ribonuclease H (RNase H) activity. Unlike most RTs, the BLV RT is enzymatically active as a monomer even after binding a DNA substrate. The enzyme shows a preference for Mg2+ over Mn2+ in both its DNA polymerase and RNase H activities. BLV RT is relatively resistant to nucleoside triphosphate analogues, which are known to be potent inhibitors of other RTs such as that of HIV.
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Affiliation(s)
- M Perach
- Sackler School of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
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15
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Huang M, Zensen R, Cho M, Martin MA. Construction and characterization of a temperature-sensitive human immunodeficiency virus type 1 reverse transcriptase mutant. J Virol 1998; 72:2047-54. [PMID: 9499059 PMCID: PMC109498 DOI: 10.1128/jvi.72.3.2047-2054.1998] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A temperature-sensitive (ts) human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) mutant was generated by charged-cluster-to-alanine mutagenesis. The mutant virus, containing three charged residues within the RT finger domain changed to alanine (K64A, K66A, and D67A), replicated normally at 34.5 but not 39.5 degrees C. Quantitating virus particle production by p24 antigen capture or virion-associated RT activity and virus infectivity by the MAGI cell assay, we found that (i) mutant virions produced at the permissive temperature were indistinguishable from wild-type virus in assays performed at the nonpermissive temperature, suggesting that the ts mutation did not impair early steps in the virus replication cycle and that the mutant RT enzyme was not ts; and (ii) virus particle production in cells transfected with the ts mutant at the nonpermissive temperature was comparable to that of wild-type virus. However, the particle-associated RT activity and infectivity of mutant virions produced at the nonpermissive temperature were greatly reduced when assays were conducted at the permissive temperature. These results are consistent with an irreversible ts event affecting RT that occurs during virus particle production. Radioimmunoprecipitation analyses revealed that both p66 and p51 RT subunits were absent from mutant virions generated at 39.5 degrees C. The presence of normal levels of HIV-1 integrase in mutant particles produced at the nonpermissive temperature was inconsistent with defective Gag-Pol synthesis or Gag-Pol incorporation into progeny virions. Furthermore, wild-type levels of the mutant Pr160(gag-pol) were detected in virions produced at the nonpermissive temperature when the HIV-1 protease was inactivated by site-specific mutagenesis. Taken together, these results are most consistent with a ts defect affecting the degradation or aberrant processing of the mutated RT during its processing/maturation within nascent particles.
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Affiliation(s)
- M Huang
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, Bethesda, Maryland 20892, USA
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16
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Reshef V, Mizrachi E, Maretzki T, Silberstein C, Loya S, Hizi A, Carmeli S. New acylated sulfoglycolipids and digalactolipids and related known glycolipids from cyanobacteria with a potential to inhibit the reverse transcriptase of HIV-1. JOURNAL OF NATURAL PRODUCTS 1997; 60:1251-60. [PMID: 9428159 DOI: 10.1021/np970327m] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Five novel diacylated sulfoglycolipids (1-5) were isolated from the cyanobacterium Scytonema sp. (TAU strain SL-30-1-4) and four novel acylated diglycolipids (6-9) were isolated from the cyanobacterium Oscillatoria raoi (TAU strain IL-76-1-2). These two groups of glycolipids and related known glycolipids isolated from these two and three other strains of cyanobacteria, Phormidium tenue (TAU strain IL-144-1), O. trichoides (TAU strain IL-104-3-2), and O. limnetica (TAU strain NG-4-1-2), were found to inhibit HIV-1 RT enzymatic activity to different extents. The structure elucidation of the various compounds is based on the selective hydrolysis of the glycerol ester moieties, GCMS analysis of the methyl ester derivatives of the liberated fatty acids, homo- and heteronuclear-2D-NMR techniques, and MS. The use of negative-ion FABMS for analyzing the combination and distribution of the fatty acids in glycolipids is demonstrated.
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Affiliation(s)
- V Reshef
- School of Chemistry, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Israel
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17
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Loya S, Rudi A, Kashman Y, Hizi A. Mode of inhibition of HIV reverse transcriptase by 2-hexaprenylhydroquinone, a novel general inhibitor of RNA-and DNA-directed DNA polymerases. Biochem J 1997; 324 ( Pt 3):721-7. [PMID: 9210394 PMCID: PMC1218486 DOI: 10.1042/bj3240721] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A natural compound from the Red Sea sponge Ircinia sp., 2-hexaprenylhydroquinone (HPH), has been shown to be a general inhibitor of retroviral reverse transcriptases (from HIV-1, HIV-2 and murine leukaemia virus) as well as of cellular DNA polymerases (Escherichia coli DNA polymerase I, and DNA polymerases alpha and beta). The pattern of inhibition was found to be similar for all DNA polymerases tested. Thus the mode of inhibition was studied in detail for HIV-1 reverse transcriptase. HPH is a non-competitive inhibitor and binds the enzyme irreversibly with high affinity (Ki=0. 62 microM). The polar hydroxy groups have been shown to be of key importance. A methylated derivative, mHPH, which is devoid of these polar moieties, showed a significantly decreased capacity to inhibit all DNA polymerases tested. Like the natural product, mHPH binds the enzyme independently at an allosteric site, but with reduced affinity (Ki=7.4 microM). We show that HPH does not interfere with the first step of the polymerization process, i.e. the physical formation of the reverse-transcriptase-DNA complex. Consequently, we suggest that the natural inhibitor interferes with the subsequent steps of the overall reaction. Since HPH seems not to affect the affinity of dNTP for the enzyme (the Km is unchanged under conditions where the HPH concentration is increased), we speculate that its inhibitory capacity is derived from its effect on the nucleotidyl-transfer catalytic reaction. We suggest that such a mechanism of inhibition is typical of an inhibitor whose mode of inhibition should be common to all RNA- and DNA-directed polymerases.
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Affiliation(s)
- S Loya
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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18
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Hizi A, Kamath-Loeb AS, Rose KD, Loeb LA. Mutagenesis by human immunodeficiency virus reverse transcriptase: incorporation of O6-methyldeoxyguanosine triphosphate. Mutat Res 1997; 374:41-50. [PMID: 9067414 DOI: 10.1016/s0027-5107(96)00217-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The high frequency of incorporation of non-complementary nucleotides by HIV-1 reverse transcriptase is likely to be a major factor in the exceptionally rapid accumulation of viral mutations during the course of AIDS infections. To investigate whether this high level of infidelity is also associated with the incorporation of nucleotide analogs, we analyzed O6-methyldeoxyguanosine triphosphate and compared the incorporation of this analog by HIV-1 reverse transcriptase to that catalyzed by other DNA synthesizing enzymes. Our results indicate that O6-methyldeoxyguanosine triphosphate serves as a substrate for DNA synthesized in vitro by HIV-1 RT on both DNA and RNA templates. The product DNA contains the modified purine; it is sensitive to the repair enzyme, O6-methylguanine methyltransferase, which specifically reacts with DNA containing methylated guanines at the O6 position. Using a forward mutation assay we demonstrated that the nucleotide analog incorporated by HIV-1 RT is mutagenic. The mutations produced are single-base substitutions opposite template thymidines and result in A:T --> G:C transitions. The incorporation of a mutagenic nucleotide by HIV-1 RT highlights the possibility of increasing the rate of mutagenesis of HIV by the use of nucleotides that form non-complementary base pairs at high frequency.
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Affiliation(s)
- A Hizi
- Department of Pathology, University of Washington, Seattle 98195, USA
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19
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Pengsuparp T, Serit M, Hughes SH, Soejarto DD, Pezzuto JM. Specific inhibition of human immunodeficiency virus type 1 reverse transcriptase mediated by soulattrolide, a coumarin isolated from the latex of calophyllum teysmannii. JOURNAL OF NATURAL PRODUCTS 1996; 59:839-842. [PMID: 8864237 DOI: 10.1021/np960399y] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Soulattrolide (1), a coumarin isolated from Calophyllum teysmannii latex, was found to be a potent inhibitor of HIV-1 reverse transcriptase (RT) with an IC50 of 0.34 microM. Inhibition was remarkably specific, with no appreciable activity being observed toward HIV-2 RT, AMV RT, RNA polymerase, or DNA polymerases alpha or beta.
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Affiliation(s)
- T Pengsuparp
- Department of Biochemistry, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand
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20
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McCormick JL, McKee TC, Cardellina JH, Boyd MR. HIV inhibitory natural products. 26. Quinoline alkaloids from Euodia roxburghiana. JOURNAL OF NATURAL PRODUCTS 1996; 59:469-471. [PMID: 8778237 DOI: 10.1021/np960250m] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Bioassay-directed fractionation of the CH2Cl2-MeOH extract of Euodia roxburghiana resulted in the isolation of two known quinoline alkaloids, buchapine (1) and 2, and three new furoquinoline alkaloids, roxiamines A, B, and C (3-5). Compounds 1 and 2 protected CEM-SS cells from the cytopathic effects of HIV-1 in vitro (EC50 0.94 and 1.64 microM, respectively), but 3-5 were inactive against HIV-1.
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Affiliation(s)
- J L McCormick
- Laboratory of Drug Discovery Research and Development, Developmental Therapeutics Program, National Cancer Institute, Frederick, Maryland 21702-1201, USA
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21
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Bokesch HR, McKee TC, Currens MJ, Gulakowski RJ, McMahon JB, Cardellina JH, Boyd MR. HIV-Inhibitory Gallotannins fromLepidobotrys staudtii. ACTA ACUST UNITED AC 1996. [DOI: 10.1080/10575639608043252] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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22
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Flavin MT, Rizzo JD, Khilevich A, Kucherenko A, Sheinkman AK, Vilaychack V, Lin L, Chen W, Greenwood EM, Pengsuparp T, Pezzuto JM, Hughes SH, Flavin TM, Cibulski M, Boulanger WA, Shone RL, Xu ZQ. Synthesis, chromatographic resolution, and anti-human immunodeficiency virus activity of (+/-)-calanolide A and its enantiomers. J Med Chem 1996; 39:1303-13. [PMID: 8632437 DOI: 10.1021/jm950797i] [Citation(s) in RCA: 148] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The anti-HIV agent (+/-)-calanolide A (1) has been synthesized in a five-step approach starting with phloroglucinol [-->5-->6-->11-->18-->(+/-)-1], which includes Pechmann reaction, Friedel-Crafts acylation, chromenylation with 4,4-dimethoxy-2-methylbutan-2-ol, cyclization, and Luche reduction. Cyclization of chromene 11 to chromanone 18 was achieved by employing either acetaldehyde diethyl acetal or paraldehyde in the presence of trifluoroacetic acid and pyridine or PPTS. Luche reduction of chromanone 18 at lower temperature preferably yielded (+/-)-1. Reduction of chromone 12, synthesized by Kostanecki-Robinson reaction from chromene 11, failed to afford (+/-)-1. The synthetic (+/-)-1 has been chromatographically resolved into its optically active forms, (+)- and (-)-1. The anti-HIV activities for synthetic (+/-)-1, as well as resultant (+)- and (-)-1, have been determined. Only (+)-1 accounted for anti-HIV activity, which was similar to the data reported for the natural product, and (-)-1 was inactive.
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Affiliation(s)
- M T Flavin
- MediChem Research, Inc., Lemont, Illinois 60439, USA
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23
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Abstract
Modern molecular biology techniques have provided valuable tools which allow for the expression of large amounts of enzyme in E. coli. For potential therapeutic targets such as HIV-1 reverse transcriptase, it is desirable that the enzyme studied is pure and correlates to the active form of the enzyme found in vivo. This poses a particular challenge for those researchers studying HIV-RT since a significant degree of heterogeneity is introduced by nonspecific proteolytic cleavage of the p66 subunit by E. coli proteases. The advantage of the purification protocol presented here is that the association of monomers is facilitated by mixing an excess of p51 subunit, which is truncated at a site that is N-terminal to known bacterial cleavage sites, with p66 protein. This avoids enzymatic processing of the larger subunit since the formation of heterodimeric RT is rapid and the dimer is stable against proteolytic cleavage. Therefore, it is possible to isolate a pure homogeneous p66/p51 heterodimer. An enzyme prepared in this manner yields crystals that defract to a 3.2-A resolution. It has also been used to study both sensitivity of HIV-1 RT mutants to azidothymidine triphosphate and the kinetics of a potent nonnucleoside RT inhibitor (L-743,726). Finally, it is interesting to note the similarity of HIV-1 RT with reverse transcriptases from other lentiviruses (FIV and EIAV RT). Both of these enzymes consist of heterodimers of p66 and p51 subunits and share other biophysical characteristics. Purification of these reverse transcriptases can, in all likelihood, be optimized by using methods similar to those described in this chapter.
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Affiliation(s)
- M W Stahlhut
- Department of Antiviral Research, Merck Research Laboratories, West Point, Pennsylvania 19486, USA
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24
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Boyer PL, Hughes SH. Analysis of mutations at position 184 in reverse transcriptase of human immunodeficiency virus type 1. Antimicrob Agents Chemother 1995; 39:1624-8. [PMID: 7492119 PMCID: PMC162796 DOI: 10.1128/aac.39.7.1624] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We have analyzed recombinant human immunodeficiency virus type 1 reverse transcriptases that contain mutations at position 184. These variants retain high levels of RNA-dependent DNA polymerase activity and show resistance to ddITP. However, the mutants varied in their ability to polymerize processively. The variants Met184Ile and Met184Val showed slight reductions in processivity relative to that of the wild-type enzyme; the variants Met184Ala and Met184Leu showed considerable reductions in their processivity.
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Affiliation(s)
- P L Boyer
- Advanced BioScience Laboratories-Basic Research Program, National Cancer Institute-Frederick Cancer Research and Development Center, Maryland 21702-1201, USA
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25
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Koller G, Graumann K, Kramer W, Sara M, Jungbauer A. Laboratory-scale production and purification of recombinant HIV-1 reverse transcriptase. JOURNAL OF CHROMATOGRAPHY. B, BIOMEDICAL APPLICATIONS 1995; 664:107-18. [PMID: 7538852 DOI: 10.1016/0378-4347(94)00468-k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
HIV-1 reverse transcriptase from the HIV-1 strain WMF 1.13 was expressed in Escherichia coli JM 105 using a pKK233-2 vector. The bacteria were cultivated in a 20-l fermentor with 14-l net volume using M9ZB medium containing bactotryptone and yeast extract. After induction of reverse transcriptase (RT) expression by addition of isopropyl-beta-D-thiogalactopyranoside the enzyme concentration was monitored. Both soluble and inclusion-body deposited RT were detected by Western blots. Inclusion-body formation was confirmed by transmission electron microscopy. Further purification of soluble and insoluble RT was investigated. After cell desintegration by enzymatic treatment combined with osmotic shock and centrifugation, the supernatant was desalted by size-exclusion chromatography and further purified by DEAE-Sepharose FF, AF-Heparin Toyopearl 650 M and Fractogel EMD TMAE 650 (S). The results of the purification steps were monitored by SDS-PAGE with silver staining, non-radioactive RT assay and protein determination with Coomassie Blue. The sediment was extracted with 6 M GuHCl and after clarification and conventional refolding, treated in the same manner as soluble RT. This method is well suited for studying fermentation conditions as well as purification conditions. The RT is expressed in approximately equal amounts as soluble and insoluble enzyme.
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Affiliation(s)
- G Koller
- Institute of Applied Microbiology, Universität für Bodenkultur, Vienna, Austria
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26
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Clark AD, Jacobo-Molina A, Clark P, Hughes SH, Arnold E. Crystallization of human immunodeficiency virus type 1 reverse transcriptase with and without nucleic acid substrates, inhibitors, and an antibody Fab fragment. Methods Enzymol 1995; 262:171-85. [PMID: 8594346 DOI: 10.1016/0076-6879(95)62017-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- A D Clark
- Center for Advanced Biotechnology and Medicine, Rutgers University, Piscataway, New Jersey 08854-5638, USA
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27
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Le Grice SF, Cameron CE, Benkovic SJ. Purification and characterization of human immunodeficiency virus type 1 reverse transcriptase. Methods Enzymol 1995; 262:130-44. [PMID: 8594344 DOI: 10.1016/0076-6879(95)62015-x] [Citation(s) in RCA: 107] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- S F Le Grice
- Division of Infectious Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4984, USA
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28
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Gu Z, Fletcher RS, Arts EJ, Wainberg MA, Parniak MA. The K65R mutant reverse transcriptase of HIV-1 cross-resistant to 2', 3'-dideoxycytidine, 2',3'-dideoxy-3'-thiacytidine, and 2',3'-dideoxyinosine shows reduced sensitivity to specific dideoxynucleoside triphosphate inhibitors in vitro. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)46902-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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29
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Bakhanashvili M, Hizi A. Interaction of the reverse transcriptase of human immunodeficiency virus type 1 with DNA. Biochemistry 1994; 33:12222-8. [PMID: 7522556 DOI: 10.1021/bi00206a027] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
During DNA synthesis, the binding of human immunodeficiency virus (HIV) reverse transcriptase (RT) to the template-primer precedes its binding to nucleotide triphosphates. The interaction of oligonucleotide DNA with HIV-1 RT was investigated by using a gel retardation assay. Both homodimeric (p66/p66) and heterodimeric (p66/p51) isoforms of HIV-1 RT were capable of binding the DNA oligomers. Thus, all further studies on the interaction of HIV-1 RT with DNA were done with heterodimeric RT. We have studied the conditions for optimal binding. The formation of the RT-DNA complex was primer-independent, and the extent of DNA binding was indistinguishable for both single-stranded and double-stranded DNA (either blunt-ended or recessed). The DNA binding activity of the RT was found to be dependent on oligonucleotide length. HIV-1 RT binds DNA with no apparent sequence specificity. Hence, this enzyme belongs to the sequence nonspecific DNA binding proteins. The interaction was found to be independent of DNA synthesis. The formation of the RT-DNA complex was not influenced by the presence of either template-complementary or noncomplementary dNTPs, indicating that neither DNA polymerization nor binding of the RT to the dNTP affects the stability of the complex. The gel retardation assay was utilized to examine also the effect of various HIV-1 RT inhibitors (i.e., AZT-TP, ddTTP, TIBO, and 3,5,8-trihydroxy-4-quinolone) on the enzyme-DNA interaction. The results indicate differences in the modes of action of these compounds.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Bakhanashvili
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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30
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Lebowitz J, Kar S, Braswell E, McPherson S, Richard DL. Human immunodeficiency virus-1 reverse transcriptase heterodimer stability. Protein Sci 1994; 3:1374-82. [PMID: 7530541 PMCID: PMC2142949 DOI: 10.1002/pro.5560030903] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Structural and biochemical evidence strongly supports a heterodimeric (p66p51) active form for human immunodeficiency virus-1 reverse transcriptase (RT). Heterodimer stability was examined by sedimentation analysis as a function of temperature and ionic strength. Using NONLIN regression software, monomer-dimer-trimer and monomer-dimer-tetramer association models gave the best fit to the analytical ultracentrifuge sedimentation equilibrium data. The heterodimer is the predominant form of RT at 5 degrees C, with a dimerization Ka value of 5.2 x 10(5) M-1 for both models. Ka values of 2.1 x 10(5) and 3.8 x 10(5) M-1 were obtained for the respective association models at 20 degrees C. RT in 50 and 100 mM Tris, pH 7.0, completely dissociates at 37 degrees C and behaves as an ideal monomeric species. The dissociation of RT as a function of increasing temperature was also observed by measuring the decrease in sedimentation velocity (sw,20). If the stabilization of the heterodimer was due primarily to hydrophobic interactions we would anticipate an increase in the association from 21 degrees C to 37 degrees C. The opposite temperature dependence for the association of RT suggests that electrostatic and hydrogen bond interactions play an important role in stabilizing heterodimers. To examine the effect of ionic strength on p66p51 association we determined the changes in sw,20 as a function of NaCl concentration. There is a sharp decrease in sw,20 between 0.10 and 0.5 M NaCl, leading to apparent complete dissociation. The above results support a major role for electrostatic interactions in the stabilization of the RT heterodimer.
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Affiliation(s)
- J Lebowitz
- Department of Microbiology, University of Alabama at Birmingham 35294
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31
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Rubinek T, McMahon JB, Hizi A. Inhibition of reverse transcriptase of human immunodeficiency virus type 1 and chimeric enzymes of human immunodeficiency viruses types 1 and 2 by two novel non-nucleoside inhibitors. FEBS Lett 1994; 350:299-303. [PMID: 7520874 DOI: 10.1016/0014-5793(94)00793-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have studied the effects of two non-nucleoside reverse transcriptase inhibitors (NNRTI), nitrophenyl phenyl sulfone (NPPS) and a potent derivative of oxathiin carboxanilide (UC-38), on enzymatically active molecular chimeras composed of complementary segments of the reverse transcriptases (RTs) of human immunodeficiency virus type 1 (HIV-1) and -2 (HIV-2). The substances inhibit only the DNA polymerase activity of HIV-1 RT with no effect on HIV-2 RT. The results suggest that there is a protein segment located between residues 158 and 190 that is critical for the inhibition by both compounds. However, there is probably a second segment that resides between residues 192 and 202, as in the case of NPPS, or residues 203 and 224, as in the case of UC-38, that is also crucial for the sensitivity of HIV-1 RT to both inhibitors.
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Affiliation(s)
- T Rubinek
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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32
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Loya S, Bakhanashvili M, Tal R, Hughes SH, Boyer PL, Hizi A. Enzymatic properties of two mutants of reverse transcriptase of human immunodeficiency virus type 1 (tyrosine 181-->isoleucine and tyrosine 188-->leucine), resistant to nonnucleoside inhibitors. AIDS Res Hum Retroviruses 1994; 10:939-46. [PMID: 7529032 DOI: 10.1089/aid.1994.10.939] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
A number of structurally diverse compounds have been shown to be potent inhibitors of the DNA polymerase activity of human immunodeficiency virus (HIV-1) reverse transcriptase (RT). The compounds can be grouped into two broad classes: nucleoside analogs and nonnucleoside inhibitors. The nonnucleoside inhibitors are quite specific for the polymerase activity of HIV-1 RT; they do not affect the polymerase activity of HIV-2 RT or the ribonuclease H (RNase H) activity of either HIV-1 RT or HIV-2 RT. Structural, biochemical, and genetic analyses showed that this group of inhibitors binds in a hydrophobic pocket near the polymerase active site. Mutations in amino acids that line this hydrophobic pocket, for example at tyrosine 181, tyrosine 188, or lysine 103, lead to enzymes that are resistant to the nonnucleoside inhibitors. We have investigated the enzymatic properties of two mutants of HIV-1 RT in which residues 181 and 188 were replaced by the corresponding amino acids in HIV-2 RT (tyrosine 181-->isoleucine and tyrosine 188-->leucine). The two tyrosine mutants closely resemble the wild-type HIV-1 RT in almost all the catalytic functions tested, including the heat stability, sensitivity of the DNA polymerase activity to inhibition by deoxynucleoside analogs, inhibition by the zinc chelator o-phenanthroline, and the Km values calculated for the DNA polymerase activity. There is, however, a slight difference in the effect of orthophenanthroline on the RNase H activity. In addition, there is a subtle disparity in the fidelity of DNA synthesis (analyzed by a mispair extension assay), thus indicating that these mutant RTs are not likely to confer any selective advantages or disadvantages to the variant virions over wild-type virus.
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Affiliation(s)
- S Loya
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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33
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Rubinek T, Loya S, Shaharabany M, Hughes SH, Clark PK, Hizi A. The catalytic properties of the reverse transcriptase of the lentivirus equine infectious anemia virus. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 219:977-83. [PMID: 7509281 DOI: 10.1111/j.1432-1033.1994.tb18580.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The reverse transcriptase (RT) of equine infectious anemia virus (EIAV) shares sequence similarity with the RTs of other lentiviruses, particularly with the RTs of human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2, respectively), the causative agents of acquired immunodeficiency syndrome (AIDS). There is a 41-42% sequence identity between EIAV RT and both HIV RTs (which have 61% sequence identity to each other). We have compared the enzymic properties of EIAV RT with those of HIV-1 RT. Several aspects of the activities of EIAV RT differ from the corresponding activities of HIV-1 RT. There are significant differences in the inhibition of the DNA polymerase activities by the deoxynucleoside triphosphate analogs, 3'-azido-2,3'-dideoxythymidine triphosphate, dideoxyTTP and dideoxyGTP and by the nonnucleoside inhibitor, tetrahydroimidazo[4,5,1-jk-1,4]benzodiazepin-2-(1H)-one and thione; in the dependence of DNA polymerase and RNase H activities on pH; in the inhibition of the DNA polymerase activities by the thiol-specific reagent N-ethylmaleimide; in the specific DNA polymerase activity; in the inhibition of the ribonuclease H activity by the zinc chelator orthophenanthroline. However, there are several cases in which EIAV RT and HIV-1 RT are more similar than was previously found for HIV-1 RT and HIV-2 RT. These include the Km values for the DNA polymerase activities, the heat stability of the DNA polymerase functions and the specific activity of the RNase H function.
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Affiliation(s)
- T Rubinek
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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34
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Bakhanashvili M, Hizi A. Fidelity of DNA synthesis exhibited in vitro by the reverse transcriptase of the lentivirus equine infectious anemia virus. Biochemistry 1993; 32:7559-67. [PMID: 7687876 DOI: 10.1021/bi00080a030] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The lentivirus equine infectious anemia virus (EIAV) shows high genetic variations. To gain insight into the relative contribution of the reverse transcription process to the EIAV mutation rate, the accuracy of DNA synthesis catalyzed in vitro by the reverse transcriptase (RT) of EIAV was determined. Since the RT of EIAV shows a relatively high sequence homology with other lentiviral RTs, most notable being the RTs of human immunodeficiency viruses (HIVs), type 1 and type 2, it was of interest to study the fidelity of EIAV RT as part of an investigation of the structure-function relationship in lentiviral RTs. Like other RTs, EIAV RT was found to lack a 3'-->5' exonuclease activity. The fidelity of EIAV RT was analyzed by studying two distinct steps that lead to base substitution mutations: nucleotide misinsertions and elongation from 3'-terminal DNA mispairs. Analysis of misincorporation rates opposite the template adenine residue in native phi x174am3 DNA showed that EIAV RT catalyzes nucleotide mismatches with a specificity of A:C >> A:G > A:A. Interestingly, the same order of specificity was also detected during mispair extension with three templates tested (i.e., phi x174am3 DNA, rRNA, and synthetic oligo DNA). The mispair extension efficiency and mispair formation appear to be affected mainly by the increase in apparent Km values, rather than by the change in Vmax values. Furthermore, EIAV RT exhibits similar mispair extension efficiencies with both RNA and DNA templates with identical surrounding sequences. However, dissimilarities were detected in mispair extension frequencies with two DNAs which have different sequences, thus emphasizing the importance of the sequences copied.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M Bakhanashvili
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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35
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Bhikhabhai R, Carlsson T, Unge T, Lövgren S, Strandberg B. Increased yield of homogeneous HIV-1 reverse transcriptase (p66/p51) using a slow purification approach. J Chromatogr A 1993; 639:67-74. [PMID: 7687250 DOI: 10.1016/0021-9673(93)83089-b] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A chromatographic procedure to purify recombinant reverse transcriptase (RT) from human immunodeficiency virus-1 is reported. A bacterial system which expressed large amounts of p66 RT polypeptide was used. The purification scheme was optimized for high-yield production of homogeneous p66/p51 RT using a combination of chromatographic matrices in the following order: Q-Sepharose, heparin-Sepharose, phenyl-Sepharose, S-Sepharose, Poly(A)-Sepharose and Q-Sepharose. The p66 polypeptide remained intact after the first chromatographic step on Q-Sepharose, where it was recovered in the non-adsorbed fraction. A high yield of p66/p51 RT was obtained when the time from application to elution of heparin-Sepharose in the second chromatographic step was prolonged. Phenyl-Sepharose was used in the next chromatographic step to separate the heterodimeric forms of RT from p66 RT on the basis of hydrophobicity. The chromatography on S-Sepharose resolved the major heterodimeric form, p66/p51, from other heterodimeric variants. Further purification was done by affinity chromatography on Poly(A)-Sepharose followed by anion-exchange chromatography on Q-Sepharose. Amounts of 25-35 mg of the pure heterodimer p66/p51 RT were recovered from 50 g of bacterial cells.
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Affiliation(s)
- R Bhikhabhai
- Department of Molecular Biology, University of Uppsala, Sweden
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36
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Hizi A, Tal R, Shaharabany M, Currens MJ, Boyd MR, Hughes SH, McMahon JB. Specific inhibition of the reverse transcriptase of human immunodeficiency virus type 1 and the chimeric enzymes of human immunodeficiency virus type 1 and type 2 by nonnucleoside inhibitors. Antimicrob Agents Chemother 1993; 37:1037-42. [PMID: 7685994 PMCID: PMC187890 DOI: 10.1128/aac.37.5.1037] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We have studied the effects of four nonnucleoside inhibitors, including the novel natural product inhibitor calanolide A, on molecular chimeras containing complementary segments of human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) reverse transcriptases (RTs). All four compounds specifically inhibited the DNA polymerase activity of HIV-1 RT but had no apparent effect on the RNase H activity of this enzyme or on the DNA polymerase or RNase H activity of HIV-2 RT. Three of these compounds showed the generally expected patterns of resistance and susceptibility with the various chimeric RTs. However, the inhibition patterns of the chimeric RTs by calanolide A provided evidence that there is a segment between residues 94 and 157 in HIV-1 RT that is critical for inhibition. However, the data also suggest that there may be a second segment located between amino acids 225 and 427 in HIV-1 RT that is also important for specifying susceptibility to the drug.
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Affiliation(s)
- A Hizi
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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37
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The interaction of illimaquinone, a selective inhibitor of the RNase H activity, with the reverse transcriptases of human immunodeficiency and murine leukemia retroviruses. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(18)98353-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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38
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Tan GT, Wickramasinghe A, Verma S, Hughes SH, Pezzuto JM, Baba M, Mohan P. Sulfonic acid polymers are potent inhibitors of HIV-1 induced cytopathogenicity and the reverse transcriptases of both HIV-1 and HIV-2. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1181:183-8. [PMID: 7683207 DOI: 10.1016/0925-4439(93)90109-e] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Four novel sulfonic acid polymers were evaluated for their in vitro HIV-1 and HIV-2 reverse transcriptase (RT) inhibitory activity and found to be equipotent against both RTs. The aromatic polymers demonstrated IC50 values that were approximately 10(3)-fold lower than those observed with the aliphatic polymers. Among the aromatic polymers, poly(4-styrenesulfonic acid) (PSS) (MW 8000; IC50 = 0.02 microgram/ml) was 3-fold more potent than poly(anetholesulfonic acid) (PAS) of approximately the same molecular weight range. The activity of PSS polymers increased in proportion to the size of the polymers and, relative to suramin, activity could be enhanced over 200-fold. These polymers also inhibited the cytopathic effect of HIV-1 at concentrations that were non-toxic to MT-4 cells. The potent RT inhibitory properties of these stable sulfonic acid polymers suggest that structure-activity studies are warranted to yield agents capable of inhibiting multiple stages of the viral process.
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Affiliation(s)
- G T Tan
- Program for Collaborative Research in the Pharmaceutical Sciences, University of Illinois, Chicago
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39
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Bakhanashvili M, Hizi A. The fidelity of the reverse transcriptases of human immunodeficiency viruses and murine leukemia virus, exhibited by the mispair extension frequencies, is sequence dependent and enzyme related. FEBS Lett 1993; 319:201-5. [PMID: 7681015 DOI: 10.1016/0014-5793(93)80067-5] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sequence variations in HIV-1 and HIV-2 probably result in part from inaccurate DNA synthesis by viral reverse transcriptases (RTs). We have studied in vitro the fidelity of both the DNA- and RNA-dependent DNA polymerization functions of the two HIV RTs, as compared to that of murine leukemia virus (MLV) RT. The two HIV RTs were less accurate than MLV RT. The mispair extension frequencies observed previously with ribosomal RNA (rRNA) template were higher than those detected with phi X174am3 DNA template with all three RTs. In the current study we have investigated whether the nature of the copied nucleic acid (RNA vs. DNA) or the template nucleotide sequences affect the accuracy of DNA synthesis. We have analyzed the fidelity of DNA synthesis with DNA sequences identical to those of the rRNA sequences previously employed for reverse transcription. The results indicate that the fidelity of DNA synthesis depends mainly on the nucleotide sequences copied by every given RT. Yet, fidelity of DNA synthesis depends not only on the sequences copied but also on the nature of the enzymes per se. It is possible that these factors are major contributors to the high mutation rates of the two human immunodeficiency viruses.
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Affiliation(s)
- M Bakhanashvili
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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40
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Li X, Amandoron E, Wainberg MA, Parniak MA. Generation and characterization of murine monoclonal antibodies reactive against N-terminal and other regions of HIV-1 reverse transcriptase. J Med Virol 1993; 39:251-9. [PMID: 7682257 DOI: 10.1002/jmv.1890390314] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We produced a series of monoclonal antibodies against the human immunodeficiency virus (HIV-1) reverse transcriptase by immunizing mice with either purified recombinant HIV-1 p66 protein or with recombinant vaccinia virus which expresses HIV-1 pol sequences. The antibodies generated were specific for the reverse transcriptase protein, and recognized only the p51 and p66 subunits of the enzyme in each of the HIV-1 viral lysates and lysates of HIV-1 infected cells. The antibodies did not cross-react with HIV-2 reverse transcriptase. Most important, several of the antibodies are unique, in that they are the first that can bind to sites close to the N-terminal. This latter region has been suggested to form part of the polymerase domain of the reverse transcriptase. None of the antibodies could neutralize either the RNA-dependent DNA polymerase or RNase H activities of either p66 or p51/66 proteins. The binding patterns of these various antibodies to p66 and p51/66 were dependent on each of three independent variables: the source of antigen amployed, the individual specificity of the antibody, and the method employed to detect reactivity. These monoclonal antibodies provide useful reagents for the study of reverse transcriptase native structure-function relationships.
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Affiliation(s)
- X Li
- Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada
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41
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Isaacs S, Kashman Y, Loya S, Hizi A, Loya Y. Petrosynol and petrosolic acid, two novel natural inhibitors of the reverse transcriptase of human immunodeficiency virus from petrosia sp. Tetrahedron 1993. [DOI: 10.1016/s0040-4020(01)80571-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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42
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43
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Warren TC, Miglietta JJ, Shrutkowski A, Rose JM, Rogers SL, Lubbe K, Shih CK, Caviness GO, Ingraham R, Palladino DE. Comparative purification of recombinant HIV-1 and HIV-2 reverse transcriptase: preparation of heterodimeric enzyme devoid of unprocessed gene product. Protein Expr Purif 1992; 3:479-87. [PMID: 1283095 DOI: 10.1016/1046-5928(92)90065-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
A procedure for producing and purifying recombinant HIV-1 and HIV-2 reverse transcriptase (RT) is described. These enzymes are produced by Escherichia coli-transformed with a plasmid containing the gene encoding for either the human immunodeficiency virus type 1 (HIV-1) or HIV-2 RT protein. Both proteins are partially processed by host cell proteases giving rise to a mixture of heterodimeric and nonheterodimeric products, which are subsequently resolved to near homogeneity by chromatography on phosphocellulose, Q-Sepharose, and hydrophobic interaction HPLC. Both HIV-1 (66/51 kDa) and HIV-2 (68/54 kDa) heterodimeric enzymes devoid of excess unprocessed (p66 or p68) precursors are isolated, enabling comparative enzymatic characterization of the fully active (and biologically relevant) heterodimeric forms. Homogenous HIV-1 and HIV-2 RT purified by this methodology exhibit near equivalent polymerase and RNase H activities.
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Affiliation(s)
- T C Warren
- Department of Biochemistry, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut 06877
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44
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Abstract
The relatively low fidelity of human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) was implicated as a major factor that contributes to the genetic variability of the virus. Extension of mismatched 3' termini of the primer DNA was shown to be a major determinant of the infidelity of HIV-1 RT. Human immunodeficiency virus type 2 (HIV-2) also shows extensive genetic variations. Therefore, we have analyzed the fidelity of the DNA-dependent DNA polymerase activity of HIV-2 RT and compared it with those of RTs of HIV-1 and murine leukemia virus (MLV). Like other retroviral RTs, the HIV-2 RT was shown to lack a 3'----5' exonuclease activity. The ability of HIV-2 RT to extend preformed 3'-terminal A:A, A:C and A:G mispairs was examined by quantitating the amount and length of extended primers. The results demonstrate a relatively efficient mispair extension by HIV-2 RT with a specificity of A:C much greater than A:A greater than A:G. The mispair extension appears to be affected mainly by the increase of apparent Km values rather than by the change in Vmax values. The relative extension frequencies from all mispairs with HIV-1 and HIV-2 RTs was 6- to 9-fold greater than that of MLV RT, suggesting that the HIV enzymes are substantially more error-prone than MLV RT.
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Affiliation(s)
- M Bakhanashvili
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel-Aviv University, Israel
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45
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Marshall WS, Beaton G, Stein CA, Matsukura M, Caruthers MH. Inhibition of human immunodeficiency virus activity by phosphorodithioate oligodeoxycytidine. Proc Natl Acad Sci U S A 1992; 89:6265-9. [PMID: 1378623 PMCID: PMC49481 DOI: 10.1073/pnas.89.14.6265] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Phosphorothioate oligodeoxynucleotides exert a sequence-independent cytoprotective effect against human immunodeficiency virus type 1 (HIV-1). We now report that phosphorodithioate-containing oligodeoxycytidines are very potent inhibitors of HIV-1 reverse transcriptase in vitro, as they exhibit an increasing inhibitory effect with length and number of phosphorodithioate internucleotide linkages. This inhibitory effect can be at least 30-fold greater with phosphorodithioate oligodeoxycytidine than for the corresponding phosphorothioate analog of similar length. In cell culture, phosphorodithioate oligodeoxycytidines are active inhibitors of syncytia formation and effectively inhibit de novo infection of target cells by HIV-1. Moreover, comparative experiments show that a deoxycytidine phosphorodithioate 14-mer is as effective an inhibitor of de novo infection as a phosphorothioate-containing 28-mer. Such potent inhibition by oligomers of relatively short length makes dithioate analogs an additional class of potential therapeutic agents against acquired immunodeficiency syndrome.
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Affiliation(s)
- W S Marshall
- Department of Chemistry and Biochemistry, University of Colorado, Boulder 80309-0215
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46
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Loya S, Tal R, Hughes S, Hizi A. The effects of cysteine mutations on the catalytic activities of the reverse transcriptase of human immunodeficiency virus type-1. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49650-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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47
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Bakhanashvili M, Hizi A. A possible role for cysteine residues in the fidelity of DNA synthesis exhibited by the reverse transcriptases of human immunodeficiency viruses type 1 and type 2. FEBS Lett 1992; 304:289-93. [PMID: 1377646 DOI: 10.1016/0014-5793(92)80640-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
HIV reverse transcriptases (RTs) have few cysteine residues relative to other RTs and retain their DNA polymerization functions following chemical modification by thiol-specific reagents. The functional role of the cysteines in the fidelity of the DNA-dependent DNA synthesis of HIV RTs has been addressed by chemical modification of the wild-type enzymes in combination with the analysis of an enzymatically active mutant HIV-1 RT in which all cysteines were modified to serines. We have observed an increase in 3'-terminal mispair extension efficiency exhibited by chemically modified HIV-1 and HIV-2 RTs. The possible involvement of cysteine residues was further substantiated using the cysteine-free mutant HIV-1 RT that displays an increased efficiency of mispair extension. These results provide evidence for a possible role of cysteine residues in the fidelity of DNA synthesis catalyzed by HIV RTs.
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Affiliation(s)
- M Bakhanashvili
- Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel
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48
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Tan GT, Miller JF, Kinghorn AD, Hughes SH, Pezzuto JM. HIV-1 and HIV-2 reverse transcriptases: a comparative study of sensitivity to inhibition by selected natural products. Biochem Biophys Res Commun 1992; 185:370-8. [PMID: 1376118 DOI: 10.1016/s0006-291x(05)80995-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
One hundred and fifty six pure natural products, which had previously been tested against HIV-1 reverse transcriptase, were evaluated for HIV-2 reverse transcriptase inhibitory activity. Compounds that lacked effect in the HIV-1 reverse transcriptase system were found also to be inactive against HIV-2 reverse transcriptase. However, compounds belonging to the benzophenanthridine and protoberberine classes of alkaloids, certain flavonoids, the iridoid, fulvoplumierin, and the ansamycin antibiotic, daunomycin, exhibited similar potencies in both enzyme systems. In contrast, HIV-2 reverse transcriptase was observed to be four-fold more sensitive toward the inhibitory effects of the ipecac alkaloids, O-methylpsychotrine sulfate heptahydrate and psychotrine dihydrogen oxalate. Such differences in susceptibilities to inhibitors may indicate subtle dissimilarities in enzyme structure and function.
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Affiliation(s)
- G T Tan
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago
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49
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Vonsover A, Loya S, Sredni B, Albeck M, Gotlieb-Stematsky T, Araf O, Hizi A. Inhibition of the reverse transcriptase activity and replication of human immunodeficiency virus type 1 by AS 101 in vitro. AIDS Res Hum Retroviruses 1992; 8:613-23. [PMID: 1381205 DOI: 10.1089/aid.1992.8.613] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
In a search for compounds active against human immunodeficiency virus type 1 (HIV-1), it was found that the novel low-molecular weight immunoenhancer ammonium trichloro(dioxyethylene-O,O'-) tellurate (AS101) suppresses production of HIV-1 in vitro. Treatment of HIV-1-infected peripheral blood mononuclear cells (PBMC) with increasing concentrations of AS101 resulted in substantial inhibition of virus production as measured by both reverse transcriptase (RT) activity and antigen presence in supernatants of treated cells. AS101 had no effect on PBMC viability, growth, or morphology up to a concentration of 15 microM for 14 days. To elucidate a possible mechanism for the inhibition of AS101, we have analyzed the effect of the drug on the catalytic functions associated with HIV RT, namely the RDDP, DDDP, and RNase H activities. RDDP and DDDP activities were impaired by the drug with calculated IC50 value of about 4 microM. On the other hand, the RNase H activity was less sensitive to AS101, with an apparent IC50 value of about 30 microM. The anti-HIV-1 activity of AS101 as reflected by inhibition of the different catalytic functions associated with viral RT, in the absence of drug-related toxicity to lymphocytes, together with its immunomodulating activity strongly argues in favor of its evaluation, as a therapeutic agent for patients with HIV infection.
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Affiliation(s)
- A Vonsover
- Central Virology Laboratory, Chaim Sheba Medical Center, Tel-Hashomer, Israel
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50
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Elder JH, Lerner DL, Hasselkus-Light CS, Fontenot DJ, Hunter E, Luciw PA, Montelaro RC, Phillips TR. Distinct subsets of retroviruses encode dUTPase. J Virol 1992; 66:1791-4. [PMID: 1310783 PMCID: PMC240941 DOI: 10.1128/jvi.66.3.1791-1794.1992] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The nonprimate lentiviruses feline immunodeficiency virus, equine infectious anemia virus, visna virus, and caprine encephalitis virus contain a gene segment in the polymerase gene that is lacking in the primate lentiviruses. A related sequence has been noted in other retroviruses, most notably the type D retroviruses. Computer searches have indicated a relatedness between this unique gene segment, termed proteaselike element and elements of both the aspartate proteinase and the dUTPase enzyme families. In this report, we show that members of both nonprimate lentiviruses and type D retroviruses possess dUTPase activity and present a formal demonstration that in feline immunodeficiency virus, the activity is encoded by the proteaselike element.
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Affiliation(s)
- J H Elder
- Department of Molecular Biology, Scripps Research Institute, La Jolla, California 92037
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