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Query: EC:2.7.7.49 (reverse transcriptase)
 31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly(I).poly(C12U) or interferon treatment inhibited multiplication of the xenotropic baboon type C endogenous retrovirus M7 in chronically infected human AV3-M7 cells, as determined by a reverse transcriptase (RT) assay and electron microscopy. Furthermore, this polynucleotide induced 2'5' oligoadenylate (2'5'A) synthetase activity. In contrast to interferon (IFN), poly(I).poly(C12U) did not give rise to the appearance of a trapping phenomenon observable by electron microscopy. When AV3-M7 cells were treated simultaneously with poly(I).poly(C12U) and anti-IFN-beta/alpha antibodies, the induction of 2'5'A synthetase was abolished without any alteration of the inhibitory effect of RT activity. Taken together, these results suggest that different mechanisms are used by poly(I).poly(C12U) and IFN in blocking type C retrovirus multiplication.
J Gen Virol 1992 Sep
PMID:The effects of poly(I).poly(C12U) and interferon on the multiplication of a mammalian type C retrovirus in human cells. 138 6

The complete RNA genome of turnip mosaic potyvirus (TuMV) was amplified by seven consecutive reverse transcriptase-polymerase chain reactions and cloned into pUC9. The viral RNA is 9830 nucleotides long and contains a single open reading frame (ORF) of 9489 bases encoding a large polyprotein of 3863 amino acids with a calculated M(r) of 358,000. The non-coding region (NCR) preceding the ORF is 129 nucleotides long and has a high AU content (70%). Its predicted secondary structure is characterized by a hairpin loop with a free energy loss of -69.9 kJ/mol. The termination codon is followed by an AU-rich NCR of 209 bases, excluding the poly(A) tail. Seven potential nuclear inclusion a proteinase (NIa-Pro) recognition heptapeptides are found in the polyprotein. Their sequences agree with consensus potyviral NIa-Pro cleavage sequences except for that at the 6K-VPg site, which is characterized by a glutamic acid residue preceding the hydrolysed peptide bond. The TuMV proteins are similar to their corresponding potyviral proteins.
J Gen Virol 1992 Nov
PMID:The complete nucleotide sequence of turnip mosaic potyvirus RNA. 143 7

As part of a continuing effort to assess genetic variation among isolates of Borrelia burgdorferi we have determined the 16S rRNA signature nucleotide makeup of two tick isolates from the USSR. Signature nucleotides were identified via reverse transcriptase primer extension sequencing of select regions of the 16S rRNA molecule. In addition, the near complete 16S rRNA sequence of one of the isolates, R-IP3, was determined and utilized in a phylogenetic assessment. The sequence was aligned with the 16S rRNA sequences of other B. burgdorferi isolates as well as with other Borrelia species. Distance matrix analyses were performed and a phylogenetic tree was constructed. These analyses demonstrate that these isolates belong to a third previously unidentified genomic group of B. burgdorferi.
J Gen Microbiol 1992 Mar
PMID:Identification of a third genomic group of Borrelia burgdorferi through signature nucleotide analysis and 16S rRNA sequence determination. 159 64

Recombinant interleukin 4 (IL-4) stimulated extracellular (EC) and intracellular (IC) production of human immunodeficiency virus (HIV) from infected human blood-derived monocytes and macrophages when incubated with the cells after but not before virus inoculation. Significant stimulation was observed in 20 of 27 experiments with monocytes (inoculated with HIV immediately after adherence) and 10 of 13 experiments with macrophages (inoculated after 5 days adherence) using a total of 30 normal donors of monocytes and macrophages, and 11 recent isolates of monocytotropic HIV strains (after one passage in mononuclear cells). Marked increases in EC and IC HIV antigen were observed in some experiments, which were comparable with the maximal stimulatory effects of other cytokines such as IL-2. IL-4 also had similar effects on infectious HIV concentration as measured by reverse transcriptase and TCID50 assays. Antibody to IL-4 prevented the stimulatory effect of the cytokine. The proportion of monocytes and macrophages infected by HIV, as determined by in situ hybridization, also increased after incubation with IL-4 for 7 days. The most marked effects were observed with HIV-infected macrophages, for which the proportion of unstimulated infected cells was lower (35 to 45% increasing to 66 to 70% with IL-4 treatment). There was also an increased proportion of cells with high granule concentrations, suggesting that IL-4 increases the intracellular concentration of viral nucleic acids. This was supported by semi-quantitative hybridization experiments showing that total HIV RNA increased in IL-4-stimulated monocytes 48 to 96 h after HIV inoculation. A marked increase in aggregates was observed on day 7 in HIV-infected monocytes treated with IL-4, compared to that in HIV-infected cells alone or IL-4-treated uninfected monocytes. These findings suggest that IL-4 stimulates HIV replication in the early phases of infection and may also facilitate virus transmission by aggregate formation.
J Gen Virol 1992 Apr
PMID:Recombinant interleukin 4 stimulates human immunodeficiency virus production by infected monocytes and macrophages. 163 80

The intra- and intergeneric relationships of the genus Actinomyces were determined by comparing long 16S rRNA sequences, generated by reverse transcriptase. All species formed a phylogenetically coherent cluster in which Actinomyces bovis, A. viscosus, A. naeslundii, A. odontolyticus and A. israelii constituted genetically well defined species. A. israelii DSM 43322 (serotype 2) was not closely related to three other strains of this species (serotype 1) and, as judged from phylogenetic distances, could be accommodated within A. naeslundii, or represent a new species. In contrast to previous findings, members of the genus Actinomyces appear to be related to Bifidobacterium bifidum. Sequence information was used to develop an oligonucleotide probe for the A. israelii serotype 1 strains, which did not react with the serotype 2 strain or with rRNA from strains of eight Actinomyces species.
J Gen Microbiol 1990 Jan
PMID:Partial 16S rRNA primary structure of five Actinomyces species: phylogenetic implications and development of an Actinomyces israelii-specific oligonucleotide probe. 169 59

The yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe transformed by plasmids containing retrotransposon from yeast or Drosophila under the control of a strong promoter show the remarkable reverse transcriptase activity. The activity results in the impaired yeast growth and decreased mitotic stability of the plasmids. The phenotypic expression of the reverse transcriptase activity is observed within 30 days.
Mol Gen Mikrobiol Virusol 1990 Aug
PMID:[Phenotypic manifestations of reverse transcriptase activity in yeast cells]. 170 Feb 91

Murine monoclonal antibodies (MAbs) gp41-1 (IgG2a) and gp41-2 (IgG1), directed against the envelope glycoprotein of human immunodeficiency virus type 1 (HIV-1), were produced and characterized. These MAbs recognized both gp160 and gp41 and reacted with divergent HIV-1 isolates. Surface binding assays using viable HIV-infected cells indicated that these MAbs were directed against surface-exposed epitopes. Both MAbs caused a reduction in reverse transcriptase activity. Syngeneic monoclonal antiidiotypic antibodies (anti-ids) against gp41-1 were also generated. Six anti-ids (agp41-11 to agp41-16) were selected by ELISA using F(ab')2 fragments of gp41-1; no reaction was observed when fragments from an irrelevant IgG2a MAb were used. Anti-ids were recognized by both gp41-1 and gp41-2 biotinylated MAbs. Competitive ELISA studies suggested that anti-ids were directed against at least three distinct idiotopes on gp41-1. All anti-ids reacted with idiotopes associated with both heavy and light chains and not with separated chains. The binding of MAbs gp41-1 and gp41-2 to HIV-infected cells was inhibited by each anti-id, except for the binding of gp41-2 which was not affected by the presence of agp41-12. Immunization of rabbits with agp41-11 and agp41-13 resulted in an antibody response against recombinant gp160. These studies indicated that these two anti-ids contain a surrogate image of the antigen recognized by gp41-1.
J Gen Virol 1991 Jan
PMID:Monoclonal idiotypic and anti-idiotypic antibodies to human immunodeficiency virus type 1 envelope glycoprotein. 170 62

The C-terminal region of human immunodeficiency virus (HIV) reverse transcriptase (RT) contains the domain responsible for RNase H activity. To determine the importance of this RNase H domain, specific changes in the C-terminal region of a recombinant RT expressed in Escherichia coli were introduced by amino acid substitutions and specific deletions. The enzyme activities of purified wild-type and mutant RT/RNase H proteins, standardized for protein content, were compared by filter assays and thermal inactivation kinetics. A point mutation of His 539----Asn produced an enzyme with a marked thermolabile RNase H function (nine-fold increase in inactivation), whereas RT function was only marginally more labile than that of the wild-type (two-fold). A second mutation, His 539----Asp, impaired both enzyme activities to a similar degree (four- to five-fold). A C-terminal deletion of 19 amino acids (aa) (aa 540 to 558) and a C-terminal truncation of 21 aa (aa 540 to 560) reduced RT as well as RNase H activity. A 130 aa deletion enzyme exhibited no RNase H activity and insufficient RT activity to allow inactivation studies. Two mutants, the 19 aa deletion and His----Asn, were introduced into proviral HIV-1 DNA clones to determine whether changes in enzyme activity, particularly RNase H activity, affected virus infectivity. Both mutants were non-infectious, indicating that the C-terminal 19 to 21 amino acids and His 539 of the RT/RNase H protein are essential for HIV replication. These results are consistent with the assumption that RNase H is essential for the infectivity of HIV-1.
J Gen Virol 1991 Jan
PMID:Mutations within the RNase H domain of human immunodeficiency virus type 1 reverse transcriptase abolish virus infectivity. 170 63

The gene coding for starch phosphorylase (EC 2.4.1.1) was isolated from a potato genomic library constructed in lambda EMBL3. It is an unusually long plant gene (16.4 kb) which encodes a preprotein of 966 amino acids. The phosphorylase coding sequence is interrupted by 14 introns whose positions do not match those of the introns in the human glycogen phosphorylase gene. A 78 amino acid central peptide unique to plant plastidial phosphorylases is hypothesized to have arisen through the mis-splicing of an intron-exon junction site in an ancestral gene. The fifth intron of the phosphorylase is very large (approximately 7 kb) and contains a copia-like transposable element inserted in the opposite orientation to that of the phosphorylase gene. This element has been named Tst1; it is bordered on the 5' and 3' sides by long terminal repeats of 285 and 283 bp respectively, which define an internal domain of 4492 bp. Tst1 contains 4 open reading frames (ORFs) that encode protein domains for a reverse transcriptase, an integrase, an RNA-binding site and a protease. Transcription of the phosphorylase gene appears to proceed unimpaired through the copia element.
Mol Gen Genet 1990 Oct
PMID:Occurrence of a copia-like transposable element in one of the introns of the potato starch phosphorylase gene. 170 27

Glutamine depletion strongly inhibits the replication of Rauscher murine leukaemia retrovirus (RLV) in vitro. Pseudomonas 7A glutaminase-asparaginase (PGA), capable of depleting glutamine and asparagine for prolonged periods, was used to determine the therapeutic effectiveness of glutamine depletion in mice infected with RLV or Friend virus. During PGA treatment of viraemic animals, serum reverse transcriptase activity fell to control levels and infected animals did not develop splenomegaly. The therapeutic results obtained with PGA compared favourably with those of azidothymidine given intraperitoneally at 30 mg/kg/day. Western blots performed on splenic tissue from control and treated animals indicated that glutamine depletion prevented readthrough of an amber codon at the gag-pol junction, stopping translation of viral mRNA at that point. Treatment of RLV-infected animals with PGA resulted in nearly a 200% increase in mean survival time even when therapy was initiated late in the course of the disease. To our knowledge, this is the first demonstration that a nutrient required for viral replication can be enzymically depleted in vivo to inhibit viral replication.
J Gen Virol 1991 Feb
PMID:Inhibition of mouse retroviral disease by bioactive glutaminase-asparaginase. 170 10


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