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

---

Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A 2.4-kb DNA fragment from the pol region of the human T-cell lymphotropic virus, encoding the protease, reverse transcriptase and a portion of the endonuclease N-terminus was stably introduced into a high-level Bacillus subtilis expression system under inducible control of the Escherichia coli lac regulatory elements. The major expression plasmid, pRTL11, contains a bacteriophage T5 promoter/lac operator element, which is controlled by lac repressor, supplied by the secondary plasmid, pBL1. Upon IPTG induction, a 90-kDa polyprotein is synthesised and subsequently proteolytically cleaved to reveal 64-kDa and 52-kDa polypeptides. Partial purification reveals that reverse transcriptase activity co-migrates with these two polypeptides.
...
PMID:Expression of biologically active human T-cell lymphotropic virus type III reverse transcriptase in Bacillus subtilis. 244 69

The reverse transcriptase polymerase of the human T-cell lymphotropic virus/lymphadenopathy-associated virus has been cloned into an expression vector and expressed in Escherichia coli. Two polypeptides of 66 and 51 kDa molecular mass are detectable in polymerase-expressing bacterial lysates with human patient sera. They are processed from a short-lived 120-kDa polyprotein precursor equivalent to a region consisting of polymerase, protease, and endonuclease. The 51 kDa protein appears to originate from the 66-kDa molecule; additional processing products are 32- and 15-kDa proteins. The bacterially expressed polymerase is enzymatically active and exhibits the template specificities, ion requirements, and response to inhibitors of the authentic enzyme. It was purified by DEAE-cellulose-, phosphocellulose-, and poly(rC)-agarose column chromatography followed by glycerol density gradient centrifugation. It copurifies with an RNase H activity, suggesting the existence of a virus-coded DNA polymerase-RNase H complex. The purified bacterial enzyme allows a safe large-scale screening for inhibitors of both activities.
...
PMID:RNase H activity associated with bacterially expressed reverse transcriptase of human T-cell lymphotropic virus III/lymphadenopathy-associated virus. 244 62

A cell line (8E5) containing a single defective copy of human immunodeficiency virus proviral DNA and producing noninfectious viral particles lacking reverse transcriptase (RT) and endonuclease proteins has recently been described (Folks, et al., (1986b) J. Exp. Med. 164, 280-290). In this report, the mutation in a full-length molecular clone of the provirus (p8E5) was mapped to a 1931-bp region of the pol gene encoding RT. The nucleotide sequence of this segment revealed a 1-base deletion 301 codons from the common amino terminus of the 64- and 51-kDa RTs. Expression of the p8E5 RT segment in Escherichia coli generated an enzymatically inactive and truncated 33-kDa protein.
...
PMID:Molecular characterization of a polymerase mutant human immunodeficiency virus. 141 27

A category of viruses has been identified which is related to human immunodeficiency virus (HIV) but is more closely related to a group of simian retroviruses (STLV-III). These viruses named HTLV-IV, LAV-II, or SBL-6669, are prevalent in West-Africa. In this study, we analysed the cross-reactivity at the protein level between HTLV-IV and HIV (HTLV-IIIB). The results indicate that most people infected with HTLV-IV have antibodies that react to the major gag protein of HIV p 24. There is also a high degree of immunologic cross-reactivity between the pol gene products of HIV and HTLV-IV. Among these the endonuclease/integrase is more conserved than the reverse transcriptase. In contrast, the envelope glycoproteins that are the most frequently detected antigens by antibodies from exposed individuals are serotype specific. These data make the env gene products the most interesting antigens for serotype specific diagnosis of human retroviruses infections.
...
PMID:A STLV-III related human retrovirus, HTLV-IV: analysis of cross-reactivity with the human immunodeficiency virus (HIV). 244 14

We have cloned several prototypic members of the family of human endogenous retroviruslike elements having a histidine tRNA primer-binding site (RTVL-H) and have determined the nucleotide sequence of one of these clones (RTVL-H2). The RTVL-H2 sequence is 5,813 nucleotides long, with long terminal repeats of 450 nucleotides. Although this particular sequence contains no long open reading frames, computer searches have revealed several segments of amino acid homology with known retroviral gene products. In the gag region of RTVL-H2, there is a segment with significant homology to a region of the gag protein p30 of type C baboon endogenous virus. In the pol region of RTVL-H2, three segments similar to the Moloney leukemia virus (MLV) pol polyprotein were detected. These correspond to parts of the protease, reverse transcriptase, and endonuclease domains of the MLV pol gene. Interestingly, the last two pol domains are equidistant in RTVL-H2 and the type C murine retroviruslike DNA sequence (MuRRS), both having deletions of equal sizes relative to the MLV pol gene. One other segment similar to a retroviral gene product was identified in the RTVL-H2 gag region. This segment has 55 to 60% amino acid homology to a 50-amino-acid region of the gag nucleic acid-binding proteins encoded by human T-cell lymphotropic viruses types I and II and bovine leukemia virus. Thus, the RTVL-H2 genome harbors sequences related to evolutionarily distant retroviruses.
...
PMID:Human endogenous retroviruslike genome with type C pol sequences and gag sequences related to human T-cell lymphotropic viruses. 244 10

The virion proteins encoded by the avian retroviral pol gene (reverse transcriptase and endonuclease) are formed by the proteolytic processing of a gag-pol fusion protein precursor. Recent studies have predicted that the avian sarcoma-leukosis virus pol precursor protein undergoes a previously undetected processing event resulting in the formation of common C termini for the endonuclease (pp32) and the beta subunit of reverse transcriptase (F. Alexander, J. Leis, D. A. Soltis, R. M. Crowl, W. Danho, M. S. Poonian, Y.-C. E. Pan, and A. M. Skalka, J. Virol. 61:534-542, 1987; D. Grandgenett, T. Quinn, P. J. Hippenmeyer, and S. Oroszlan, J. Biol. Chem. 260:8243-8249, 1985). This processing event removes 37 amino acids, thus defining a new pol domain. In this report, we present evidence that this C-terminal domain is translated as part of the gag-pol precursor but is not required for replication of the virus in tissue culture cells.
...
PMID:A C-terminal domain in the avian sarcoma-leukosis virus pol gene product is not essential for viral replication. 244 90

We have cloned the entire pol gene of human immunodeficiency virus type 2 into a high-level Escherichia coli expression system. Induction of cultures containing the recombinant plasmid, p2RTL1, leads to rapid accumulation of polypeptides of 66, 54, and 34 kilodaltons. We have designated the larger polypeptides reverse transcriptase, and we have designated the smaller polypeptide endonuclease. Purification of reverse transcriptase via ion-exchange and affinity chromatography yields the 66-kilodalton polypeptide, with which reverse transcriptase activity is associated. Purified enzyme furthermore displays a higher apparent molecular weight than its counterpart from human immunodeficiency virus type 1.
...
PMID:A single 66-kilodalton polypeptide processed from the human immunodeficiency virus type 2 pol polyprotein in Escherichia coli displays reverse transcriptase activity. 245 82

We have determined the nucleotide sequence of the Drosophila retrotransposon 1731. 1731 is 4648 bp long and is flanked by 336 bp terminal repeats (LTRs) previously described as being reminiscent of provirus LTRs. The 1731 genome consists of two long open reading frames (ORFs 1 and 2) which slightly overlap each other. The ORF 1 and 2 present similarities with retroviral gag and pol genes respectively as shown by computer analysis. The pol gene exhibits several enzymatic activities in the following order: protease, endonuclease and reverse transcriptase. It is possible that 1731 also encompasses a ribonuclease H activity located between the endonuclease and reverse transcriptase domains. Moreover, comparison of the 1731 pol gene with the pol region of copia shows similarities extending over the protease, endonuclease and reverse transcriptase domains. We show that codon usage in the two retrotransposons is different. Finally, no ORF able to encode an env gene is detected in 1731.
...
PMID:Primary structure and functional organization of Drosophila 1731 retrotransposon. 245 22

Single genotypic variants of HIV-I, contained in a parental cytopathic HIV-I isolate, were isolated by molecular cloning and propagated in susceptible cells. Two such HIV-I clones, designated N1T-E and N1T-A, exhibited similar restriction endonuclease maps but strikingly different biological activities. Infection of T lymphocytes or monocytes by clone N1T-E was characterized by slow kinetics and lack of significant cytopathic effects, but high reverse transcriptase activity levels in culture supernatants of chronically-infected cells. Clone N1T-A, like the parental HIV-I isolate, exhibited fast kinetics of infection in T cells and monocytes and strong cytopathicity in these cells. Full characterization of the low-cytopathic virus in comparison to the structurally similar cytopathic clone may facilitate the elucidation of the molecular basis of HIV cytopathogenicity.
...
PMID:Low-cytopathic infectious clone of human immunodeficiency virus type I (HIV-I). 245 68

The 3'----5' exonuclease activity of the Klenow fragment operates in 3'-end labeling of DNA fragments. In the presence of excess deoxyribonucleoside 5'-triphosphates (dNTPs), the 5'----3' polymerase activity is dominant over the exonuclease activity. However, in the presence of a small amount of dNTPs, the exonuclease activity removed deoxyribonucleoside 5'-monophosphate (dNMP) incorporated in the 3'-end of a DNA strand by the polymerase activity. We found that the radioactivity of incorporated dNMP decreased remarkably in the course of 3'-end labeling by the Klenow fragment. On the other hand avian myeloblastosis virus (AMV) reverse transcriptase also possesses the polymerase activity. The decline of the incorporated radioactivity was not observed, indicating that the enzyme has neither exo- nor endonuclease activities. Furthermore, the level of the incorporated radioactivity was the same as that obtained by the Klenow fragment. We conclude that AMV reverse transcriptase is easier to use than the Klenow fragment for labeling the 3'-end of a DNA fragment.
...
PMID:Avian myeloblastosis virus reverse transcriptase is easier to use than the Klenow fragment of DNA polymerase I for labeling the 3'-end of a DNA fragment. 246 Nov 16


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---