Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q9NRP7 (fused)
 58,367 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

More than a dozen of hybrid proteins possessing reactivity with human immunodeficiency virus-type 1-(HIV-1) infected cells and cytotoxicity have been produced and studied by several groups. These proteins are prepared either by chemical cross-linking of a toxin and a carrier molecule or by expressing fused genes of the two moieties. These cytotoxic agents have been investigated to eliminate HIV-1-infected cells in vitro. The ID50 of these agents range from pM to nM. This article compares the results of the various approaches and discusses the limits and potential of immunoconjugates for AIDS therapy.
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PMID:Potential use of immunoconjugates for AIDS therapy. 150 18

The pol gene of all retroviruses is expressed as a gag-pol fusion protein which is proteolytically processed to produce all viral enzymes. In the human immunodeficiency virus (HIV), the gag and pol genes overlap by 241 nucleotides with pol in the -1 phase with respect to gag. The gag-pol fusion is produced via a -1 ribosomal frameshifting event that brings the overlapping, out-of-phase gag and pol genes into translational phase. Frameshifting occurs at a so called 'shift site' 8-10 nucleotides upstream of a hairpin loop which may play a role in the regulation of frameshifting. We have fused this region of HIV-1 to the 5' end of the firefly luciferase reporter gene in order to quantitatively measure ribosomal frameshifting both in cells and by in vitro translation. A series of 2'-O-methyl oligonucleotides was designed to specifically bind the sequences which flank the gag-pol hairpin. Ribosomal frameshifting is enhanced up to 6 fold by those oligonucleotides which bind the area just 3 to the stem. Oligonucleotides which bind 5' to the stem have no effect on frameshift efficiency. In addition, we have constructed a series of fusion genes which mimic the effect of the bound oligonucleotides with intramolecular hairpins. The results suggest that increasing RNA secondary structure downstream of the shift site increases the frequency of ribosomal frameshifting, and that this effect can be mimicked by antisense oligonucleotides.
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PMID:Enhancement of ribosomal frameshifting by oligonucleotides targeted to the HIV gag-pol region. 150 80

The human immunodeficiency virus type 1 Rev protein controls expression of certain viral RNAs by binding to these RNAs in the nucleus. To investigate how dominant negative Rev mutants inhibit Rev function, we fused such mutants to hormone-dependent localization signals from the glucocorticoid receptor. Each was found to have fully potent inhibitory activity whether expressed in the nucleus or in the cytoplasm. Wild-type Rev colocalized with an inhibitory fusion protein, implying that the two proteins interact. The resulting complexes accumulated within nuclei in response to steroids but had no effect on expression of Rev-responsive mRNAs. A mutation known to block in vitro oligomerization of Rev abolished both complex formation and inhibitory activity of the mutant fusion proteins. Thus, trans-dominant inhibition of Rev does not require competition for nuclear substrates but may instead reflect the ability of a mutant to form nonfunctional complexes with the wild-type protein in vivo.
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PMID:trans-dominant inhibition of human immunodeficiency virus type 1 Rev occurs through formation of inactive protein complexes. 154 42

Levels of trans activation of the human immunodeficiency virus type 1 long terminal repeat (HIV-1 LTR) by the virally encoded transactivator Tat show marked species-specific differences. For example, levels of transactivation observed in Chinese hamster ovary (CHO) rodent cells are 10-fold lower than those in human cells or in CHO cells that contain the human chromosome 12. Thus, the human chromosome 12 codes for a protein or proteins that are required for optimal Tat activity. Here, the function of these cellular proteins was analyzed by using a number of modified HIV-1 LTRs and Tats. Neither DNA-binding proteins that bind to the HIV-1 LTR nor proteins that interact with the activation domain of Tat could be implicated in this defect. However, since species-specific differences were no longer observed with hybrid proteins that contain the activation domain of Tat fused to heterologous RNA-binding proteins, optimal interactions between Tat and the trans-acting responsive RNA (TAR) must depend on this factor(s).
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PMID:Human chromosome 12 is required for optimal interactions between Tat and TAR of human immunodeficiency virus type 1 in rodent cells. 160 63

We have established a genetic assay for the multimerization of retroviral gag polyproteins. This assay is based on the GAL4 two-hybrid system for studying protein-protein interactions (S. Fields and O. Song, Nature (London) 340:245-246, 1989). In our initial experiments, we generated Saccharomyces cerevisiae plasmids that separately express the GAL4 DNA-binding and GAL4 activation domains fused to the human immunodeficiency virus type 1 (HIV-1) gag polyprotein, Pr55gag. The coexpression of these two hybrid proteins in S. cerevisiae results in the association of the GAL4 domains and the potent activation of an integrated GAL4-responsive lacZ indicator gene. Similar results were obtained with plasmids encoding GAL4-Moloney murine leukemia virus (M-MuLV) gag polyprotein hybrid proteins. In contrast, the heterologous GAL4-HIV-1 gag and GAL4-M-MuLV gag fusion proteins were unable to interact with each other to induce lacZ expression. The results suggest that this yeast system provides a rapid and specific assay for the interactions of retroviral gag proteins that occur during virion assembly.
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PMID:Genetic assay for multimerization of retroviral gag polyproteins. 162 70

Visna virus encodes a posttranscriptional regulatory protein that is functionally analogous to the Rev trans activator of human immunodeficiency virus type 1. Here, we demonstrate that the known functional organization of the human immunodeficiency virus type 1 Rev trans activator is shared by the distantly related visna virus Rev protein. In particular, both Rev proteins contain an N-terminal domain marked by a highly basic core motif that determines RNA sequence specificity, as well as a second C-terminal domain containing an essential leucine-rich motif that functions as an activation domain. Chimeric proteins consisting of the binding domain of one Rev protein fused to the activation domain of the other were fully functional in the viral sequence context cognate for the binding domain. We also describe derivatives of visna virus Rev bearing a defective activation domain that displayed a trans-dominant negative phenotype in transfected cells. These visna virus Rev mutants may prove useful in the derivation of transgenic animals resistant to this agriculturally important retroviral pathogen.
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PMID:Conserved functional organization of the human immunodeficiency virus type 1 and visna virus Rev proteins. 164 96

Transcriptional regulatory mechanisms found in lentiviruses employ RNA enhancer elements called trans-activation responsive (TAR) elements. These nascent RNA stem-loops are cis-acting targets of virally encoded Tat effectors. Interactions between Tat and TAR increase the processivity of transcription complexes and lead to efficient copying of viral genomes. To study essential elements of this trans activation, peptide motifs from Tats of two distantly related lentiviruses, equine infectious anemia virus (EIAV) and human immunodeficiency virus type 1 (HIV-1), were fused to the coat protein of bacteriophage R17 and tested on the long terminal repeat of EIAV, where TAR was replaced by the R17 operator, the target of the coat protein. This independent RNA-tethering mechanism mapped activation domains of Tats from HIV-1 and EIAV to 47 and 15 amino acids and RNA-binding domains to 10 and 26 amino acids, respectively. Thus, a minimal lentivirus Tat consists of 25 amino acids, of which 15 modify viral transcription and 10 bind to the target RNA stem-loop.
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PMID:A minimal lentivirus Tat. 165 92

Vectors derived from the Escherichia coli filamentous phage, fd-tet, expressing parts of the human immunodeficiency virus (HIV) gag genes were constructed and analyzed. The immunoreactive domain of HIV Gag antigens was produced in the form of a fusion protein, with a phage minor coat protein, called protein III, playing an important role in phage infectivity. A micropanning procedure, utilizing the strong affinity of biotinylated antibody to streptavidin, was applied for the selection of clones. A simple preparation procedure consisting of polyethyleneglycol precipitation of the recombinant phage from the E. coli supernatant allowed us to detect HIV antigens by enzyme-linked immunosorbent assay (ELISA). Cloned FUSE-gag, as isolated using anti-Gag RL4.72.1 monoclonal antibody (mAb), contained a nucleotide sequence coding for 91 amino acids of HIV Gag p24. It specifically reacted with the mAb in the ELISA. Construction of the mAb-selectable phages permitted localization of epitopes for mAb. Infectivity of the phage clone was specifically neutralized by the anti-HIV mAb. Immunoelectroblotting analysis of recombinant phages revealed the presence of an about 65-kDa band reacting with anti-HIV mAb. This Mr corresponded to the size of the fused form of the FUSE 1 protein III. Human sera from HIV-infected and uninfected individuals reacted with recombinant protein III, as well as the original form of protein III.
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PMID:Expression of an immunogenic region of HIV by a filamentous bacteriophage vector. 167 67

Retroviral RNA is copied into DNA by reverse transcriptase when the viral genome enters into its life cycle. In the case of human immunodeficiency virus (HIV), massive amounts of unintegrated viral DNA reportedly appear in the early phase of primary infection. However, the relationship between the accumulation of this DNA and the cytopathic effect (CPE) remains obscure. In an attempt to delineate this association, we examined the appearance of the unintegrated viral DNA by means of two experimental systems: (1) primary infection of highly susceptible MOLT-4#8 cells and (2) induction of CPE by cell-fusion of persistently infected MOLT-4#8 cells. A correlation was observed between the accumulation of unintegrated viral DNA and the appearance of CPE, both when MOLT-4#8 cells were infected with cell-free virus and when persistently infected MOLT-4#8 cells were co-cultured with uninfected cells. Persistently infected cells did not fuse spontaneously in culture, because they lack the CD4-molecule on their surfaces. However, when treated with polyethylene glycol (PEG), the cells fused, exhibited ballooning degeneration, and released fewer viruses. After PEG treatment, unintegrated viral DNA also appeared. Since such DNA is generally not detected in persistently infected cells, it is possible that some cellular mechanism exists to suppress the synthesis of viral DNA and that the fusion induced by PEG treatment cancels the suppression. Treatment of persistently infected cells with Ca2+ ionophore and Ca2+ antagonist also resulted in the accumulation of unintegrated viral DNA and inhibited virus release. These findings suggest that the induction of unintegrated HIV DNA may be an effective strategy for reducing the release of the virus.
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PMID:Unintegrated DNA in cells infected in vitro with human immunodeficiency virus (HIV): a new approach to suppression of virus release. 169 87

The human immunodeficiency virus (HIV) enhancer element is important in the regulation of HIV gene expression. A number of cellular proteins have been demonstrated to bind to the NF-kappa B motifs in this element. The genes encoding several of these proteins, including members of the rel family and PRDII-BF1, have been cloned. We characterized the binding of proteins encoded by the human c-rel and PRDII-BF1 genes to HIV NF-kappa B motifs and related enhancer elements. Both the human c-rel protein and two proteins derived from the PRDII-BF1 gene by alternative splicing bound specifically to the HIV NF-kappa B motif and related enhancer elements found in the immunoglobulin kappa, class I major histocompatibility complex, and interleukin-2 receptor genes. To determine the role of these factors in regulating HIV gene expression, we fused the cDNAs encoding either of the two proteins derived by alternative splicing of the PRDII-BF1 gene or the c-rel gene to the DNA binding region of the yeast transcription factor GAL4. GAL4 binding sites were inserted in place of the native HIV enhancer sequences in an HIV long terminal repeat chloramphenicol acetyltransferase construct. Cotransfection of these constructs revealed that c-rel was a strong activator of basal HIV gene expression but did not result in synergistic effects in the presence of tat. PRDII-BF1-derived cDNAs did not result in stimulation of either basal or tat-induced activated gene expression. These results indicate that multiple enhancer binding proteins may potentially regulate HIV in both a positive and negative manner.
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PMID:Regulation of human immunodeficiency virus enhancer function by PRDII-BF1 and c-rel gene products. 172 88


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