Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.8 (polynucleotide phosphorylase)
 723 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The RNAs extracted from purified preparations of the Indiana and New Jersey serotypes of vesicular stomatitis virus were polyadenylylated in vitro by using polynucleotide phosphorylase and sequence determination was carried out by the dideoxynucleotide method using reverse transcriptase and dT8AC primer. On both virus RNAs a short stretch of adenylic acid residues is present between the regions coding for the leader and N protein mRNAs. Other features of the RNA sequences of the two viruses are compared to each other and to published data.
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PMID:Sequences of vesicular stomatitis virus RNA in the region coding for leader RNA, N protein mRNA, and their junction. 22 65

Spin-labeled copolymers of 4-thiouridine and uridine (ls4U,U)n] that contain various amounts of spin label (l) were synthesized by either (i) chemical alkylation of the 4-thiouridine-uridine copolymers (s4U,U)n prepared by copolymerizing 4-thiouridine 5'-diphosphate (s4UDP) and UDP or (ii) copolymerization of spin-labeled s4UDP with UDP using polynucleotide phosphorylase. The effect of (s4U,U)n and (ls4U,U)n on avian myeloblastosis virus (AMV) RNA-dependent DNA polymerase (RNA-dependent DNA nucleotidyltransferase, EC 2.7.7.7; reverse transcriptase) was studied to determine whether the presence of potentially reactive thiol groups or spin labels enhances the inhibitory properties of the copolymers as compared to (U)n. Inhibition by (s4U,U)n gradually increases as the percentage of thiolation increases. Enhanced inhibition by (s4U,U)n appears to be due to the interaction of the thiol groups of (s4U,U)n with the thiol group(s) of the polymerase, because inhibition by (s4U,U)n (8% thiolated) in the presence of dithiotreitol resembles that by (U)n. In contrast, inhibition by (ls4U,U)n containing 3% spin label resembles that by (U)n; however, increasing the spin label to 6% or 12% results in enhanced inhibition by (ls4U,U)n as compared to that by (U)n, and dithiothreitol has no effect on enhanced inhibition by (ls4U,U)n. These results suggest that the mechanism of inhibition observed with (ls4U,U)n with a ls4U:U ratio > 1:33 differs from the mechanism for (s4U,U)n and involves complex formation between the spin label and the essential Zn2+ of RNA-dependent DNA polymerase.
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PMID:Reactivity of reverse transcriptase toward (s4U,U)n copolymers and spin-labeled nucleic acid lattices. 615 32

To help understand the role of polyadenylation in Escherichia coli RNA metabolism, we constructed an IPTG-inducible pcnB [poly(A) polymerase I, PAP I] containing plasmid that permitted us to vary poly(A) levels without affecting cell growth or viability. Increased polyadenylation led to a decrease in the half-life of total pulse-labelled RNA along with decreased half-lives of the rpsO, trxA, lpp and ompA transcripts. In contrast, the transcripts for rne (RNase E) and pnp (polynucleotide phosphorylase, PNPase), enzymes involved in mRNA decay, were stabilized. rnb (RNase II) and rnc (RNase III) transcript levels were unaffected in the presence of increased polyadenylation. Long-term overproduction of PAP I led to slower growth and irreversible cell death. Differential display analysis showed that new RNA species were being polyadenylated after PAP I induction, including the mature 3'-terminus of 23S rRNA, a site that was not tailed in wild-type cells. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated an almost 20-fold variation in the level of polyadenylation among three different transcripts and that PAP I accounted for between 94% and 98.6% of their poly(A) tails. Cloning and sequencing of cDNAs derived from lpp, 23S and 16S rRNA revealed that, during exponential growth, C and U residues were polymerized into poly(A) tails in a transcript-dependent manner.
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PMID:Analysis of the function of Escherichia coli poly(A) polymerase I in RNA metabolism. 1059 33

The hypothesis that vestiges of the ancestral RNA-dependent RNA polymerase involved in the replication of RNA genomes of Archean cells are present in the eubacterial RNA polymerase beta' subunit and its homologues is discussed. We show that in the DNA-dependent RNA polymerases from the three cellular lineages a very conserved sequence of eight amino acids also found in a small RNA-binding site previously described for the E. coli polynucleotide phosphorylase and the S1 ribosomal protein is present. The optimal conditions for the replicase activity of the avian myeloblastosis virus reverse transcriptase are presented. The evolutionary significance of the in vitro modifications of substrate and template specificities of RNA polymerases and reverse transcriptases is also discussed.
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PMID:The origin and early evolution of nucleic acid polymerases. 1153 40