Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.4 (RNase H)
 2,751 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A plasmid that consists of an 812-base-pair segment containing the replication origin of plasmid ColE1 and of a 1240-base-pair segment containing a beta-lactamase gene has been constructed. The plasmid DNA has three principal sites where transcription is initiated in vitro. One is located in the ColE1 segment 555 nucleotides upstream from the origin. Most transcription from this site extends past the origin; some of the transcripts form hybrids spontaneously with the template at their 3' portions. Cleavage of these transcripts by RNase H generates 3' termini at the origin region. When DNA polymerase I is included in the reaction along with RNA polymerase and RNase H, dAMP or dCMP is added directly onto the cleaved RNA molecules, most of which retain the intact 5' terminus. The addition of a deoxyribonucleotide to the cleaved RNA can be regarded as the first step of ColE1 DNA synthesis. Once it has served as a primer, the RNA is eliminated from the product by RNase H.
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PMID:Formation of an RNA primer for initiation of replication of ColE1 DNA by ribonuclease H. 615 50

Antisense peptide nucleic acids (PNA) can inhibit bacterial gene expression with gene and sequence specificity. Using attached carrier peptides that aid cell permeation, the antisense effects when targeting essential genes are sufficient to prevent growth and even kill bacteria. However, many design uncertainties remain, including the difficult question of target sequence selection. In this study, we synthesized 90 antisense peptide-PNAs to target sequences in a head to tail manner across the entire length of the mRNA encoding beta-lactamase. The results from this scan pointed to the start codon region as most sensitive to inhibition. To confirm and refine the result, a higher-resolution scan was conducted over the start codon region of the beta-lactamase gene and the essential Escherichia coli acpP gene. For both genes, the start codon region, including the Shine-Dalgarno motif, was sensitive, whereas antisense agents targeted outside of this region were largely ineffective. These results are in accord with natural antisense mechanisms, which typically hinder the start codon region, and the sensitivity of this region should hold true for most bacterial genes as well as for other RNase H-independent antisense agents that rely on a steric blocking mechanism. Therefore, although other design parameters are also important, the start codon region in E. coli mRNA is the most reliable target site for antisense PNAs.
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PMID:The translation start codon region is sensitive to antisense PNA inhibition in Escherichia coli. 1502 10