Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

A mutant of Rous sarcoma virus was constructed in which the nine amino acids that separate the CA and NC sequences in the Gag protein were deleted. The spacer peptide deletion mutant produced particles containing the normal complement of viral RNA and all of the viral proteins, including reverse transcriptase. Though electron microscopy revealed particles of normal morphology, the particles were noninfectious. The normally slow maturation of the CA protein, which involves cleavage of the spacer peptide from the carboxy terminus, was bypassed in this mutant, and the association between CA and the internal components of the core appears to have been disrupted. The results suggest that the spacer peptide has an essential role in directing folding and/or oligomerization of the CA subunits within the capsid structure.
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PMID:Necessity of the spacer peptide between CA and NC in the Rous sarcoma virus gag protein. 839 79

Production of defective virus particles during the early stage of Rous sarcoma virus (RSV) infection of chicken embryo fibroblasts (CEF) was examined. RSV harvested 2 days post infection (2pi) had 10 to 30 times lower specific infectivity (focus forming units/unit reverse transcriptase activity) than 5pi harvest. Virus particles produced on day 2 contained less env proteins than particles harvested on day 5. The amount of other viral proteins was equal in particles harvested on day 2 and day 5. Analysis of infected cells revealed that these cells synthesized less env proteins on day 2 than on day 5. RSV RNA in infected cells was spliced normally on day 2. Infection at a low multiplicity of infection (moi) prolonged the production of defective particles. When infection was initiated by a low moi (0.01), particles harvested on day 5 had the same characteristics as 2pi particles after infection with a high moi (1.0). We conclude that the low infectivity of early harvest is due to the reduced amount of env proteins in virus particles, which is a consequence of the reduced env protein synthesis.
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PMID:Production of env-deficient rous sarcoma virus (RSV) early after infection. 915 53

Application of neurotrophic factors (NFs) to the cut stump of motor nerves of neonatal rats confers neuroprotection from trauma-induced neuronal death. To test whether motoneurons are capable of responding to endogenously produced NFs, facial motoneurons were genetically modified in vivo to express several NFs and then tested for their response to peripheral nerve damage. Replication-defective adenoviral vectors [Adv. Rous sarcoma virus (RSV)-nf] representing three families of NFs were constructed that carried genes for brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), glial cell-derived neurotrophic factor (GDNF), and nerve growth factor. Media from cultured cells transduced with Adv. RSV-nf contained NFs that supported the survival of cultured chick sensory neurons in the same manner as recombinant NF standards. When Adv.RSV-nf or an adenoviral vector containing the beta-galactosidase gene (Adv.RSV-beta-gal) were injected into the facial muscles of neonatal rats the vectors were retrogradely transported to the facial nucleus where the NFs or beta-gal were expressed. A fraction (approximately 10%) of the neurons were transduced as demonstrated by reverse transcriptase-PCR, histochemistry, and immunocytochemistry. In the case of Adv.RSV-BDNF, Adv.RSV-CNTF, and Adv.RSV-GDNF, a significant portion of the facial nucleus neurons was protected, 16.5, 18.2, and 53.3%, respectively, from death after axotomy, showing that neurons are capable of transporting the Adv. RSV-nf, expressing the recombinant NF genes, and responding to the NFs. In the case of Adv.RSV-GDNF, a greater number of facial nucleus motoneurons survived than were transduced, indicating that neighboring untransduced neurons were protected by the GDNF expressed by the transduced neurons by a paracrine mechanism.
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PMID:Targeted transduction of CNS neurons with adenoviral vectors carrying neurotrophic factor genes confers neuroprotection that exceeds the transduced population. 925 62

The 5' untranslated region of Rous sarcoma virus (RSV) RNA is a highly ordered structure involved in multiple processes in the viral replication cycle. One of these structures, referred to as the U5-IR stem, is located immediately upstream of the 5' end of the primer binding site. Disruption of its base pairing results in a decrease in initiation of reverse transcription (D. Cobrinik, A. Aiyar, Z. Ge, M. Katzman, H. Huang, and J. Leis, J. Virol. 65:3864-3872, 1991). In the present study, the length of the U5-IR stem structure has been extended by insertions of different sequences which decrease the efficiency of reverse transcription, in vivo and in vitro. Reverse transcription is rescued partially by placing single-stranded bulges into the middle of the extended duplexes. Nucleotide substitutions or insertions into the loop region of the U5-IR stem also decrease the efficiency of reverse transcription, suggesting that these sequences may specifically interact with reverse transcriptase. Surprisingly, all of the extended stem mutations cause significant RNA packaging defects. In contrast, nucleotide insertions or base substitutions in the U5-IR loop do not affect RNA packaging. These data indicate that the reverse transcription initiation complex and RNA packaging apparatus are influenced by the same region of RSV RNA and that each process is differentially sensitive to changes in sequence and/or secondary structure.
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PMID:Multiple biological roles associated with the Rous sarcoma virus 5' untranslated RNA U5-IR stem and loop. 931 47

We examined the recently synthesized and characterized polyoxometalate compound (NH4)10[Co2Sb2W20 O70(H2O)6] (POM1). The inhibitory potency of POM1 was studied in tissue culture experiments with uninfected and Rous sarcoma virus (RSV)-infected chicken embryo fibroblasts (CEF) in vivo. We measured a considerable decrease in total cellular phosphotyrosine content in treated infected cells in vivo. POM1 treatment of SR-RSV-A infected CEF in vivo resulted in decreased pp60v-src activity, possibly due to a reduced rate of v-src translation caused by the inhibitory effect of POM1 on the RSV encoded reverse transcriptase activity (RT) activity. In further studies we were able to demonstrate the inhibitory effect of this complex on the RT activity of RSV in vitro and in vivo.
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PMID:A new polyoxometalate complex inhibits retrovirus encoded reverse transcriptase activity in vitro and in vivo. 945 99

The direct repeat (DR) sequences flanking the src gene in Rous sarcoma virus are essential posttranscriptional control elements; at least one copy of this sequence is necessary for cytoplasmic accumulation of unspliced viral RNA. These sequences promote Rev-independent human immunodeficiency virus type 1 expression, suggesting they act as constitutive transport elements (CTEs). To determine which regions of this sequence are critical for CTE function, mutations in the downstream DR were generated and tested in a viral deletion construct lacking src and the upstream DR. Two single-point mutations and three different clustered mutations caused substantial reductions in reverse transcriptase activity, Gag protein levels, and unspliced viral RNA in the cytoplasm. Three conserved regions of the CTE, including nucleotides 8844 to 8847, 8862 to 8864, and 8868 to 8870, were most sensitive to inactivation by mutagenesis.
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PMID:Mutational analysis of the rous sarcoma virus DR posttranscriptional control element. 952 71

Gag p19 protein (MA) of the transformation-defective Rous sarcoma virus mutant, tdPH2010, has a point mutation at nucleotide 376 (G to A) that results in an amino-acid change at residue 126 of p19 (Glu to Lys). This single amino-acid change is the cause of the aberrantly fast migration of this protein on SDS-polyacrylamide gels. To study the biological significance of the mutation, we introduced this mutation into a transformation-defective derivative of the molecularly cloned Rous sarcoma virus, SRA2, and examined its effect on virus replication. The virus possessing the mutation in its gag p19 gene had 50% slower replication as measured by the amount of reverse transcriptase as well as gag p27 protein (CA) in the culture media. Glu at position 126 appears to be important for efficient production of Rous sarcoma virus in vitro.
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PMID:A single amino-acid substitution in gag p19 protein (MA) of Rous sarcoma virus suppresses virus production from infected cells. 960 59

The first description of an active form of a recombinant human T-cell leukemia virus type 1 (HTLV-1) reverse transcriptase (RT) and subsequent predictions of its amino acid sequence and quaternary structure are reported here. By using amino acid alignment methods, the NH2 and COOH termini of the RT, RNase H (RH), and integrase (IN) domains of the Pol polyprotein were determined. The HTLV-1 RT seems to be unique since its NH2 terminus is probably encoded by the pro open reading frame (ORF) fused downstream, via a transframe peptide, to the polypeptide encoded by the pol ORF. The HTLV-1 Pol amino acid sequence was revealed to be highly similar to that of Rous sarcoma virus (RSV), particularly at the RT-RH hinge region. These two domains remain linked for RSV; this may also be the case for HTLV-1. In light of these results, RT, RT-RH, and RT-RH-IN genes were constructed and introduced into His-tagged protein expression vectors. The corresponding proteins were synthesized in vitro, and the DNA polymerase activities of different protein combinations were tested. Solely the RT-RH-RT-RH-IN combination was found to have a significant activity level. Velocity sedimentation analysis suggested that the HTLV-1 RT-RH and RT-RH-IN monomers are likely associated in an oligomeric structure, probably of the alpha3/beta type.
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PMID:Human T-cell leukemia virus type 1 reverse transcriptase (RT) originates from the pro and pol open reading frames and requires the presence of RT-RNase H (RH) and RT-RH-integrase proteins for its activity. 965 93

Some ribosome-inactivating proteins (RIPs) with RNA-N-glycosidase activity on 28S rRNA require, for maximal inactivation of ribosomes, the presence of tRNA. tRNA(Trp) specifically up-regulates gelonin, the RIP from Gelonium multiflorum. The same tRNA is the primer of the reverse transcriptase of Rous sarcoma virus (RSV) and of its mutant (RAV-1) which lacks the src gene. Here we demonstrate that gelonin is more active in inhibiting endogenous protein synthesis by lysates of RSV-transformed or RAV-1-infected cells and that such increase in activity correlates with the increased amount of primer tRNA(Trp) in the cells.
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PMID:Primer tRNA(Trp) of RSV-transformed or RAV-1-infected cells up-regulates the antiribosomal activity of gelonin. 981 Apr 63

The effect of weak direct and alternative magnetic fields adjusted to cyclotron frequencies of ions of polar amino acids leads to a functional inactivation of the recombinant reverse transcriptase of Rous sarcoma virus, which is coupled with the proteolysis of this enzyme.
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PMID:[Molecular mechanisms of the biological effects of weak magnetic fields. V. Inactivation in vitro of recombinant Rous sarcoma virus reverse transcriptase under the combined action of weak direct and low-frequency alternating magnetic fields, adjusted to the cyclotron resonance of polar amino acid ions]. 1007 17


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