Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The synthesis of several nucleic acid block polymers of the general type dGn.rCidCk is described. The key steps in this procedure were the joining of dCk oligomers, protected at the 3'-OH with an acetyl group, to rCi oligomers by T4 DNA ligase and the purification of the products by RPC-5 column chromatography. The block polymers were characterized by 20% polyacrylamide gel electrophoresis, UV and CD spectra, analytical Cs2SO4 buoyant density analyses, helix-coil transitions and S1 nuclease studies. NMR studies on one member of this series, dGn.rC11dC16, were reported recently (Selsing, E., Wells, R.D., Early, T.A., and Kearns, D.R. (1978) Nature 275, 249-250). The NMR studies and the results described herein indicate that these block polymers are linear duplexes with two adjoining conformations yet are hydrogen-bonded and base-stacked throughout with minimal disruption of the helix at the junction of the two conformations. Computer model building studies described in the following paper (Selsing, E., Wells, R.D., Alden, C.J., and Arnott, S. (1979) J. Biol. Chem. 254, 5417-5422) predict that these nucleic acids contain a bend at the junction region.
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PMID:Polynucleotide block polymers consisting of a DNA.RNA hybrid joined to a DNA.DNA duplex. Synthesis and characterization of dGn.rCidCk duplexes. 44 59

A cloned DNA segment from Bacillus subtilis containing 21 tRNA genes was introduced into Escherichia coli. In the B. subtilis genome, these tRNA genes are located after an rRNA gene set and before tandem terminators. The rRNA and tRNA genes are thought to represent a single transcriptional unit. However, another putative promoter occurs after the second tRNA gene within the tRNA gene cluster and has a sequence compatible with both the major B. subtilis (sigma 43 type) promoter and the major E. coli promoter. The B. subtilis 21-tRNA-gene cluster was introduced into E. coli to see whether this promoter would be recognized in E. coli, to determine the start point of transcription in the E. coli system, and to see whether mature B. subtilis tRNAs would be transcribed and processed in E. coli. Expression was evaluated by monitoring levels of aminoacylation of mature tRNAs extracted from E. coli containing plasmids with or without the B. subtilis tRNA genes and by examining profiles of isoaccepting species on columns of RPC-5. S1 nuclease mapping was performed to define the starting point for transcription. The results indicated that a putative promoter located within the B. subtilis tRNA gene region was functional when cloned into E. coli and that it initiated at the same nucleotide as it does in B. subtilis. In addition, at least some B. subtilis tRNA genes could be transcribed and processed in E. coli to mature tRNAs capable of accepting an amino acid.
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PMID:Expression in Escherichia coli of Bacillus subtilis tRNA genes from a promoter within the tRNA gene region. 308 55