Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019693 (HIV)
 170,526 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 55 residue peptide corresponding to the nucleocapsid protein of HIV-1 (NCp7) containing two zinc binding domains as well as three truncated peptides were synthesized by Fmoc-based solid phase synthesis using the fragment condensation approach. Circular dichroism (CD) data support a conformational model in trifluoroethanol/buffer solution consisting of two helical segments at the chain ends with two Zn-modules in the center of the molecule. CD titration experiments show that the synthetic protein binds two equivalents of Zn2+ stoichiometrically, and the Zn2+ induced conformational changes are completely reversible by addition of EDTA. NCp7 and its S-acetamidomethylated analog (NCp7-Acm), devoid of the zinc co-ordination centers, exhibit preferential binding to RNA with a Kd = approximately 10(-9) M irrespective of the cysteine modification as determined by filter binding assays. The binding affinity of the NCp7 protein to single-stranded DNA is lower than to RNA. Binding to double-stranded DNA is lower than to ssDNA. The NCp7-Acm protein exhibits reduced single-stranded DNA binding affinity compared to the unmodified protein. Nucleic acid binding analyses with the fragments of NCp7 protein suggest that two basic amino acid stretches are involved in RNA binding of the NCp7.
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PMID:Conformational and nucleic acid binding studies on the synthetic nucleocapsid protein of HIV-1. 842 19

Retroviral nucleocapsid and gag-precursor proteins from all known strains of retroviruses contain one or two copies of an invariant sequence, Cys-X2-Cys-X4-His-X4-Cys, that is populated with zinc in mature particles. Modification of cysteine or histidine residues results in defective packaging of genomic viral RNA and formation of non-infectious particles, making these structures potentially attractive targets for antiviral therapy. We recently reported that aromatic C-nitroso ligands of poly(ADP-ribose) polymerase preferentially destabilize one of the two (Cys-X2-Cys-X28-His-X2-Cys) zinc-fingers with concomitant loss of enzymatic activity, coincidental with selective cytocidal action of the C-nitroso substituted ligands on cancer cells. Based on the occurrence of (3Cys, 1His) zinc-binding sites in both retroviral nucleocapsid and gag proteins and in poly(ADP-ribose) polymerase, we reasoned that the C-nitroso compounds may also have antiretroviral effects. We show here that two such compounds, 3-nitrosobenzamide and 6-nitroso-1,2-benzopyrone, inhibit infection of human immunodeficiency virus HIV-1 in human lymphocytes and also eject zinc from isoalted HIV-1 nucleocapsid zinc fingers and from intact HIV-1 virions. Thus the design of zinc-ejecting agents that target retroviral zinc fingers represents a new approach to the chemotherapy of AIDS.
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PMID:Inhibition of HIV-1 infectivity by zinc-ejecting aromatic C-nitroso compounds. 842 89

The highly conserved zinc fingers in retroviral nucleocapsid (NC) proteins have the general structure Cys-(X)2-Cys-(X)4-His-(X)4-Cys. Human immunodeficiency virus type 1 (HIV-1) contains two Zn2+ fingers, and mutants were constructed in which the native sequence of each Zn2+ finger was maintained but their positions in the NC protein were changed. Mutants had either two first-finger sequences (pNC1/1), two second-finger sequences (pNC2/2), or reversed first- and second-finger sequences (pNC2/1). Cells transfected with mutant or wild-type clones produced similar levels of Tat, Gag, Pol, and Env proteins, formed syncytia, and shed viruslike particles that were indistinguishable by electron microscopy. However, the pNC2/1 and pNC2/2 mutants were inefficient in packaging genomic RNA (less than 15% of wild-type levels), whereas the pNC1/1 mutant packaged approximately 70% of wild-type levels of RNA. No infectious virus could be detected with either the pNC2/1 or pNC2/2 mutants, whereas the pNC1/1 mutant appeared to sustain a low level of replication and reverted to a competent wild-type-like viral species after a 2- to 4-week lag period. The data strongly suggest that the two Zn2+ fingers of HIV-1 are not functionally equivalent and that the first Zn2+ finger in the Gag precursor plays a more prominent role in RNA selection and packaging. The data also indicate that both Zn2+ fingers in the mature NC protein play as yet unknown roles in viral assembly or the early stages of the viral infection process.
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PMID:The two zinc fingers in the human immunodeficiency virus type 1 nucleocapsid protein are not functionally equivalent. 851 Feb 14

The L1 protein occurs at high concentrations in neutrophils, monocytes, certain reactive tissue macrophages, squamous mucosal epithelia, and reactive epidermis. It constitutes in fact about 60% of the neutrophilic cytosol protein fraction. The two L1 chains (L1H and L1L) are referred to by a bewildering collection of names, various authors having different preferences (MRP-8 and MRP-14; CFA or calgranulin A and B). The most recent proposal is calprotectin because of its calcium-binding properties and antimicrobial effect shown in vitro. L1 belongs to the S-100 protein family and may be involved in the regulation of keratinocyte proliferation and differentiation. It exists at high levels in blood and interstitial tissue fluid in several infectious, inflammatory, and malignant disorders, and it is released abundantly in foci of granulocytes and macrophages. The C-terminal sequence of the L1H chain has been shown to be identical to the N-terminus of peptides known as neutrophil immobilizing factors. Such an activity of L1 could be important for the accumulation of vital granulocytes, while L1 released from neutrophils, macrophages and epithelial cells might exert antimicrobial activity, perhaps by depriving microorganisms of zinc. The minimum inhibitory concentrations of L1 in vitro were found to be 4-32 mg/l for Candida albicans, 64 mg/l for Staphylococcus aureus, 64-256 mg/l for S. epidermidis, and 256 mg/ml for Escherichia coli and Klebsiella spp. Killing was observed at 2-4 times higher concentrations. In patients with HIV infection, those who developed oral candidiasis had significantly lower parotid L1 levels than those who did not (67 micrograms/l vs. 216 micrograms/l).
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PMID:The leucocyte protein L1 (calprotectin): a putative nonspecific defence factor at epithelial surfaces. 852 6

The viral integrase (IN) protein is the only viral protein known to be required for integration of the human immunodeficiency virus type 1 (HIV-1) genome into the host cell DNA, a step in the viral life cycle that is essential for viral replication. To better understand the relationship between in vitro IN activity and IN-mediated integration of viral DNA in an infected cell, we characterized the effects of 13 IN mutations on viral replication in cultured cells. Using HIV-1 genomes that express the hygromycin resistance gene and do not express the HIV-1 env gene, we generated stocks of pseudotype virus coated with the murine leukemia virus amphotropic envelope glycoprotein, containing either wild-type or mutant HIV-1 IN. All mutants produced normal amounts of physical particles, as measured by reverse transcriptase activity and capsid protein (p24) concentration, but they formed three groups based on infectious titer and synthesis of viral DNA. Changes at the three highly conserved acidic residues in the IN core domain (D-64, D-116, and E-152) impair provirus formation without affecting viral DNA synthesis or the accumulation of viral DNA in the nucleus of the infected cell, a phenotype predicted by each mutant's lack of in vitro integrase activity. Mutations at positions N-120, R-199, and W-235 minimally affect in vitro integrase activity, but infectious titers are severely reduced, despite normal synthesis of viral DNA, implying a defect during integration in vivo. Mutations in the zinc binding region (H12C, H16V, and H16C), S81R, and a deletion of residues 32 through 275 yield noninfectious particles that synthesize little or no viral DNA following infection, despite wild-type levels of reverse transcriptase activity and viral RNA in the particles. The two latter classes of mutants suggest that IN can affect DNA synthesis or integration during infection in ways that are not appreciated from currently used assays in vitro.
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PMID:Human immunodeficiency virus type 1 integrase mutants retain in vitro integrase activity yet fail to integrate viral DNA efficiently during infection. 855 8

Based on the selective binding of proteins and DNA to distinct filter materials a double-layered dot blot radio assay was developed to evaluate the binding of DNA to HIV-1 integrase. In this assay the DNA-binding was found to be independent of Mn2+ concentration, inhibited by concentrations of Mg2+ above 5 mM, abolished by zinc chelation and inhibited by monoclonal antibodies reacting with either the N-terminal or C-terminal regions of integrase. Atomic absorption spectroscopy revealed the molar ratio between integrase and zinc to be close to 1. It is concluded that both the N-terminal and the C-terminal regions of integrase are involved in DNA-binding and that the reported double-layered dot blot radio assay is well suited for further characterization of the integrase.
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PMID:Characterization of the DNA-binding activity of HIV-1 integrase using a filter binding assay. 855 1

HIV-EP1 is a C2H2 type zinc finger protein which binds to DNA kappa B site present in the long terminal repeat of HIV provirus. Previously we have reported zinc chelators having histidine--pyridine--histidine skeleton and were successful in inhibiting the DNA binding of HIV-EP1 by removing zinc from the zinc finger domain. Aiming at the potentiation of the inhibitory activity of our previous zinc chelators, herein synthesized were novel chelators comprising pyridine and aminoalkanethiol. These showed marked inhibitory activity on the DNA binding of HIV-EP1. In particular, one of them having a bis(2-mercaptoethyl) amino side chain showed inhibitory activity (IC50, approximately 4 microM) 10 times stronger than that of the strongest inhibitor that we reported previously. It appeared that these inhibited the DNA binding of HIV-EP1 by a mechanism distinct from that of the previous histidine-based inhibitors.
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PMID:Metal-chelating inhibitors of a zinc finger protein HIV-EP1. Remarkable potentiation of inhibitory activity by introduction of SH groups. 855 19

Many priniciples of sequence-specific DNA recognition have been established over the past decade, largely from structural studies of protein-DNA and drug-DNA complexes. On the basis of these principles, it has been possible to design or select variants of known structural motifs, including zinc-fingers and minor groove-binding drugs, that bind desired sequences. Here we describe a strategy, based on transcriptional termination in bacteria, to identify specific RNA-binding peptides using the arginine-rich RNA-binding motif as a framework. Peptides were isolated from two combinatorial libraries that bind tightly and specifically to the Rev response element of HIV. It appears that alpha-helical peptides resembling Rev were selected from one library whereas new peptides that probably do not form helices were selected from the other, suggesting that the arginine-rich motif may be a particularly versatile framework for recognizing RNA structures.
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PMID:Selection of RNA-binding peptides in vivo. 860 Mar 95

The HIV-1 nucleocapsid protein, NCp7, is characterized by two CCHC zinc finger motifs which have been shown to stoichiometrically bind zinc in mature virions. Moreover, this binding of zinc proves to be critical in various NCp7 functions, especially in the encapsidation process. To further understand the central role of zinc binding to NCp7, we closely investigated the zinc binding properties of NCp7 and various deleted or substituted derivatives. To this end, the fluorescence of wither the naturally occurring Trp37 or the conservatively substituted Trp16 was used to monitor the binding of zinc to the N- and C-terminal finger motifs, respectively. At pH 7.5, the NCp7 proximal motif was found to bind zinc strongly with 2.8 x 10(14) M-1 binding constant about five times higher than the NCp7 distal motif. Moreover, the binding of zinc to one finger motif decreased the affinity of the second one, and this negative cooperativity was shown to be related to the spatial proximity of the zinc-saturated finger motifs. The binding seemed to be almost equally driven by entropy and enthalpy, and the binding information was essentially encoded by the finger motifs themselves whereas the other parts of the protein only played a marginal stabilization role. As expected, the Cys and His residues of the CCHC motifs were critical and competition between protons and zinc ions to these residues induced a steep pH-dependence of the zinc binding constants to both sites. Taken together, our data provide further evidence for the nonequivalence of the two NCp7 finger motifs.
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PMID:Zinc binding to the HIV-1 nucleocapsid protein: a thermodynamic investigation by fluorescence spectroscopy. 861 1

Human immunodeficiency virus type 1 integrase (HIV-1 IN) catalyzes both 3'-donor processing and strand transfer reactions. Previous studies have determined that the N-terminal region, a putative zinc finger, is capable of binding Zn2+. The function of zinc coordination to this domain, however, is still unknown. In this report, we present evidence that Mg2+-dependent 3'-donor processing by HIV-1 IN is enhanced by the addition of Zn2+ in vitro. This activity is inhibited in the presence of the chelator 1,10-phenanthroline (OP). In addition, the Mg2+-dependent 3'-donor processing activity is more sensitive to the concentration of IN than is the Mn2+-dependent activity. A combination of dimethyl sulfoxide (DMSO) and poly(ethylene glycol) (PEG) was found to further activate the Mg2+-dependent 3'-donor processing activity while diminishing the Mn2+-dependent activity. These results suggest factors such as substrate-length, concentration of IN, Zn2+ coordination, and protein-protein interactions are important for efficient and specific donor processing activity with Mg2+ in vitro.
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PMID:Zinc stimulates Mg2+-dependent 3'-processing activity of human immunodeficiency virus type 1 integrase in vitro. 862 7


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