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)

Sequences of human beta-globin mRNA were determined by analysis of complementary DNA. beta-mRNA was transcribed into double-stranded cDNA by RNA-dependent DNA polymerase. cDNA was cut by restriction endonucleases and the fragments were terminally labeled by means of polynucleotide kinase and [gamma-32P]ATP. After purification, fragments were degraded by snake venom phosphodiesterase. Alternatively single-stranded [32P]cDNA was prepared by transcription in the presence of [alpha-32P]dCTP and actinomycin D; the product was digested by endonuclease IV and degraded by snake venom phosphodiesterase. cDNA tracts obtained by both labeling methods enabled us to construct a sequence for the translated and 3'-terminal untranslated regions of human beta-mRNA.
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PMID:Human beta-globin messenger RNA. III. Nucleotide sequences derived from complementary DNA. 6 58

A 226-nucleotide fragment was derived from alfalfa mosaic virus RNA 4 (ALMV RNA 4), the subgenomic messenger for viral coat protein, and its sequence was deduced by in vitro labeling with polynucleotide kinase and application of RNA sequencing techniques. The fragment contains the 3'-terminal 45 nucleotides of the coat protein cistron and the complete 3'-noncoding region of 182 nucleotides. The total length of RNA 4 was calculated to be 881 nucleotides. AlMV RNAs 1, 2 and 3 were elongated with a 3'-terminal poly(A) stretch and subjected to sequence analysis by using a specific primer, reverse transcriptase and chain terminators. This revealed and extensive homology between the 3'-terminal 140 to 150 nucleotides of all four ALMV RNAs. Despite a number of base substitutions, the secondary structure of the homologous region is highly conserved. The observed homology indicates that, as with RNA 4, the sites with a high affinity for the viral coat protein are located at the 3'-termini of the genomic RNAs.
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PMID:Nucleotide sequence of the 3'-noncoding region of alfalfa mosaic virus RNA 4 and its homology with the genomic RNAs. 53 14

Upon reverse transcription and cloning manipulations with virion RNAs of several plant viruses, namely beet yellows virus, brome mosaic virus, and potato virus X, we came across a significant background synthesis of cDNA on the virion RNA template in vitro independent of exogenous primers added. When tested with beet yellow virus RNA template, several commercial preparations of avian myeloblastosis virus (AMV) reverse transcriptase showed the background activity monitored by the [alpha-32P]dNTP incorporation in vitro, while the enzyme from murine moloney leukemia virus (MMLV) was found strictly exogenous-primer-dependent. To detect possible nucleic acid contaminations in reverse transcriptase, the enzyme preparations from several commercial sources were incubated with [gamma-32P]ATP and polynucleotide kinase. The labeled material from AMV reverse transcriptase preparations comigrated with a tRNA marker in polyacrylamide gels and was found to be RNase-sensitive. The MMLV reverse transcriptase preparations were free from such a contamination. These results indicate that the exogenous-primer-independent cDNA synthesis by some AMV reverse transcriptases could be due to a contaminating tRNA (or its low-molecular-weight degradation products) serving as an endogenous primer.
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PMID:Exogenous primer-independent cDNA synthesis with commercial reverse transcriptase preparations on plant virus RNA templates. 138 74

Oligodeoxynucleoside methylphosphonates, nucleic acid analogues that contain nonionic, 3'-5'-linked methylphosphonate internucleotide bonds, can be used to control mRNA function in living cells. In order to use analogues of defined sequence in biochemical and biological experiments, methods have been developed to characterize the chain length and sequence of oligodeoxyribonucleoside methylphosphonates and to study their interaction with mRNA. Methylphosphonate oligomers that terminate at the 5' end with a 3'-5' internucleotide phosphodiester bond are readily phosphorylated by polynucleotide kinase. Treatment of these 32P end labeled oligomers with aqueous piperidine randomly hydrolyzes the methylphosphonate linkage and upon gel electrophoresis produces a ladder of oligomers, which allows the chain length of the oligomer to be determined. The sequence of 32P end labeled oligonucleoside methylphosphonates can be determined by a modified chemical sequencing procedure. The interaction of the oligomers with rabbit globin mRNA was studied. The oligomers hybridize with mRNA in agarose gels. The stability of the hybrids increases with increasing chain length of the oligomer. The binding site of the oligomers on mRNA can be determined by using the oligomer as a primer for reverse transcriptase. The length of the resulting transcript is determined by polyacrylamide gel electrophoresis after removal of the methylphosphonate primer by treatment with piperidine. The results indicate that binding and priming ability of the oligonucleoside methylphosphonates are affected by the secondary structure of the mRNA.
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PMID:Characterization of sequence-specific oligodeoxyribonucleoside methylphosphonates and their interaction with rabbit globin mRNA. 241 82

The mtDNA of the African frog, Xenopus laevis, has a triple-stranded displacement loop (D-loop) structure at the origin of heavy strand DNA replication. The major species of displacing strands has a length of 1670 nucleotides, approximately 3 times the length of mouse or human D-loop mtDNA strands. We report experiments that precisely map the termini of the D-loop strand within a revised sequence of the origin region. Analysis of D-loop mtDNA strands labeled in vitro at the 5' end using polynucleotide kinase and [gamma-32P]ATP reveals microheterogeneity at the 5' end. The ends detected by this technique are located in the vicinity of several matches to a sequence element, denoted CSB-1, that is conserved in this location in several vertebrate mtDNA genomes. The 3' ends of D-loop mtDNA strands labeled in vitro by limited extension with avian myeloblastosis virus reverse transcriptase and [gamma-32P] ATP are homogeneous. The sequence signals that may help specify the arrest of DNA replication at this site are discussed. The nucleotide sequence that we report for this region contains 53 discrepancies in comparison with a previously published sequence of this region of the Xenopus laevis mtDNA genome (Roe, B. A., Ma, D.-P., Wilson, R. K., and Wong, J.F.-H. (1985) J. Biol. Chem. 260, 9759-9774). Our sequence also contains a 142-nucleotide portion of the 5' end of the 12 S rRNA gene that was omitted from the sequence published by Roe et al.
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PMID:Mapping of the displacement loop within the nucleotide sequence of Xenopus laevis mitochondrial DNA. 242 98

We have identified a nucleolytic activity in Escherichia coli infected by bacteriophage T4 that introduces cuts in the ribosome binding site of at least two T4 mRNAs. Cutting takes place specifically in the GGAG sequences that are complementary to the 3' end of 16S rRNA (Shine-Dalgarno sequence). The nature of this nucleolytic cut has been investigated by reverse transcriptase mapping, anti-mRNA mapping, utilization of the vaccinia virus guanylyltransferase, and labeling by polynucleotide kinase. We have compared the sequences of target mRNAs with an mRNA of similar sequence but that is not a substrate for the nuclease. This allowed us to narrow down the possibilities for sequence elements that determine nuclease recognition. We hypothesize that this nuclease plays a physiological role in the inhibition of expression of a class of phage proteins.
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PMID:A nuclease that cuts specifically in the ribosome binding site of some T4 mRNAs. 305 95

Globin messenger RNA, isolated from human peripheral blood reticulocytes, was transcribed into complementary DNA by use of the RNA-dependent DNA polymerase of avian myeloblastosis virus. The complementary DNA was then transcribed into (32)P-labeled complementary RNA by E. coli RNA polymerase in the presence of alpha-(32)P-labeled ribonucleoside triphosphates. The fingerprint pattern obtained from ribonuclease T1 digests of human globin complementary RNA was specific and reproducible. Different patterns were obtained from digests of duck, mouse, and rabbit globin complementary RNA. The fingerprint patterns obtained from digests of purified natural human 10S globin messenger RNA, labeled in vitro with (125)I or with [gamma-(32)P]ATP and polynucleotide kinase, were similar to that of the complementary RNA but contained some additional oligonucleotides. Sufficient nucleotide sequence information has been obtained from about 50% of the intermediate sized oligonucleotides (8-14 base residues long), to make possible examination of correspondence between these nucleotide sequences and globin amino-acid sequences. Approximately 70% of these oligonucleotide sequences can be matched to unique amino-acid sequences in the alpha- or beta-globin chains. The other 30% do not match known amino-acid sequences and presumably correspond to untranslated portions of the mRNA; some of these sequences, however, can be matched to amino-acid sequence in the abnormally long segment of the alpha chain of hemoglobin Constant Spring, which is thought to result from a chain-termination mutation.
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PMID:Nucleotide sequences of human globin messenger RNA. 413 9

Boronated oligonucleotides are potential candidates for boron neutron capture therapy, antisense technology, and as tools in molecular biology. The biological properties of dodecathymidylic acids containing one or more 5-(o-carboran-1-yl)-2'-deoxyuridine residues at different locations within the oligonucleotide chain were studied. 5-(o-Carboran-1-yl)-2'-deoxyuridine containing oligonucleotides manifested marked increased lipophilicity and resistance to 3'- or 5'-phosphodiesterases compared to the corresponding unmodified oligomer. They were substrates for T4 polynucleotide kinase and primers for Escherichia coli polymerase I and human immunodeficiency virus type 1 reverse transcriptase but not for human DNA polymerase alpha and beta. They also formed heteroduplexes that were substrates for E. coli RNase H, an essential property for antisense technology. These studies indicate that the carboranyl-containing oligonucleotides have desirable properties that need to be exploited further in the design of novel biopharmaceuticals.
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PMID:Carboranyl oligonucleotides. 3. Biochemical properties of oligonucleotides containing 5-(o-carboranyl-1-yl)-2'-deoxyuridine. 863 34

We found a novel inhibitor specific to eukaryotic DNA polymerase epsilon(pol epsilon) from plant cultured cells, Nicotina tabacum L. The compound (compound 1) was a dipeptide alcohol, L-homoserylaminoethanol. The 50% inhibition of pol epsilon activity by the compound was 43.6 microg/mL, and it had almost no effect on the activities of the other eukaryotic DNA polymerases such as alpha, beta, gamma and delta, prokaryotic DNA polymerases, nor DNA metabolic enzymes such as human telomerase, human immunodeficiency virus type 1 reverse transcriptase, T7 RNA polymerase, human DNA topoisomerase I and II, T4 polynucleotide kinase and bovine deoxyribonuclease I. Kinetic studies showed that inhibition of pol epsilon by the compound was non-competitive with respect to both template-primer DNA and nucleotide substrate. We succeeded in chemically synthesizing the stereoisomers, L-homoserylaminoethanol and D-homoserylaminoethanol, and found both were effective to the same extent. The IC(50) values of L- and D-homoserylaminoethanols for pol epsilon were 42.0 and 41.5 microg/mL, respectively. This represents the second discovery of a pol epsilon-specific inhibitor, and the first report on a water-soluble peptide-like compound as the inhibitor, which is required in biochemical studies of pol epsilon.
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PMID:L-Homoserylaminoethanol, a novel dipeptide alcohol inhibitor of eukaryotic DNA polymerase from a plant cultured cells, Nicotina tabacum L. 1498 Jun 8

Traditional Chinese medicinal plants are a treasure house for screening novel inhibitors of DNA polymerases and DNA topoisomerases from mammals; in the present study, nine lanostane-type triterpene acids were found in sclerotium of Poria cocos. Among the nine compounds, only dehydroebriconic acid could potently inhibit DNA topoisomerase II (topo II) activity (IC(50) = 4.6 microM), while the compound moderately inhibited the activities of DNA polymerases alpha, beta, gamma, delta, epsilon, eta, iota, kappa and lambda only from mammals, to similar extents. Another compound, dehydrotrametenonic acid, also showed moderate inhibitory effects against topo II (IC(50) = 37.5 microM) and weak effects against all the polymerases tested. Both compounds showed no inhibitory effect against topo I, higher plant (cauliflower) DNA polymerase I (alpha-like polymerase) or II (beta-like polymerase), calf thymus terminal deoxynucleotidyl transferase, human immunodeficiency virus type-1 reverse transcriptase, prokaryotic DNA polymerases such as the Klenow fragment of E. coli DNA polymerase I, Taq DNA polymerase and T4 DNA polymerase, or DNA metabolic enzymes such as T 7 RNA polymerase, T4 polynucleotide kinase and bovine deoxyribonuclease I. These findings suggest that dehydroebriconic acid and dehydrotrametenonic acid should be designated as topo II-preferential inhibitors, although they also moderately inhibited all the mammalian DNA polymerases tested. Both dehydrotrametenonic acid and dehydroebriconic acid could prevent the growth of human gastric cancer cells, and their LD(50) values were 63.6 and 38.4 microM, respectively. The cells were halted at the G1 phase in the cell cycle. The relation between the structure of triterpene acids and their inhibitory activities is discussed.
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PMID:A novel DNA topoisomerase inhibitor: dehydroebriconic acid, one of the lanostane-type triterpene acids from Poria cocos. 1507 95


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