Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The drug resistance genes on the r-determinants component of the composite R plasmid NR1 were mapped on the EcoRI restriction endonuclease fragments of the R plasmid by cloning the fragments using the plasmid RSF2124 as a vector. The sulfonamide (Su) and streptomycin/spectinomycin (Sm/Sp) resistance genes are located on EcoRI fragment G of NR1. The expression of resistance to mercuric ions (Mer) requires both EcoRI fragment H and I of NR1. The expression of chloramphenicol (Cm) and fusidic acid (Fus) resistance requires EcoRI fragments A and J of NR1. The kan fragment of the related R plasmid R6-5 can substitute for Eco RI fragment J of NR1 in the expression of Cm and Fus resistance. The structural genes for Cm and Fus resistance appear to be a part of an operon whose expression is controlled by the same promoter.
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PMID:Mapping of the resistance genes of the R plasmid NR1. 14 19

Multiple drug resistance plasmid NR1 is shown to code for at least 10 low molecular weight RNAs. These species, ranging in size from 60 to 120 nucleotides, have been purified from minicells by two-dimensional gel electrophoresis and characterized by RNase T1 fingerprinting. Hybridization of purified RNAs to restriction endonuclease digests of NR1 DNA indicates that most are derived from the resistance transfer factor region of the plasmid genome. One RNA was found to be coded by the transposable tetracycline resistance element Tn10, and several are associated with DNA fragments that contain origins of replication.
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PMID:Low molecular weight RNA species encoded by a multiple drug resistance plasmid. 35 92

A 1.45-megadalton segment of DNA cloned from a miniplasmid derived in vivo from a copy number mutant of the R plasmid NR1 has been shown to contain all functions essential for incompatibility and autonomous plasmid replication in Escherichia coli. Specific endonuclease cleavage sites within this DNA segment that localize functions required for replication have been mapped. A 0.45-megadalton fragment that specifies the FII incompatibility of NR1 has been identified within the replication region, and DNA fragments containing this incompatibility region, but lacking other functions required for replication, have been cloned.
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PMID:Structural and functional analysis of cloned DNA segments containing the replication and incompatibility regions of a miniplasmid derived from a copy number mutant of NR1. 36 43

The region of plasmid NR1 concerned with resistance to Hg2+ and organomercurials consists of sequences found on restriction endonuclease fragments EcoRI-H and EcoRI-I. When both fragments were cloned together into a derivative of plasmid ColE1, the hybrid plasmid conferred properties indistinguishable from those of the parental plasmid, NR1: resistance to Hg2+ and to the organomercurials merbromin and fluoresceinmercuric acetate and the inducible synthesis of the enzyme mercuric reductase. When fragment EcoRI-I was cloned into plasmid ColE1, cells containing the plasmid was as sensitive to Hg2+ and organomercurials as plasmidless strains. When fragment EcoRI-H was cloned into ColE1, cells with the hybrid plasmid were hypersensitive to Hg2+ and organomercurials. This hypersensitivity was inducible by prior exposure to low, subtoxic Hg2+ or merbromin levels. It was associated with an inducible hyperbinding activity attributed to a gene governing Hg2+ uptake and found on fragment EcoRI-H (which contains the proximal portion of a mercuric resistance [mer] operon).
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PMID:Hypersensitivity to Hg2+ and hyperbinding activity associated with cloned fragments of the mercurial resistance operon of plasmid NR1. 38 20

A physical map of the composite R plasmid NR1 has been constructed using specific cleavage of deoxyribonucleic acid (DNA) by the restriction endonuclease EcoR-. Digestion of composite NR1 DNA by EcoRI yields thirteen fragments. The six largest fragments (designated A to F) are from the resistance transfer factor component that harbors the tetracycline resistance genes (RTF-TC). The seven smallest fragments (designated G to M) are from the r-determinants component that harbors the chloramphenicol (CM), streptomycin-spectinomycin (SM/SP), and sulfonamide (SA) resistance genes. The largest fragment of several RTF-TC segregants of NR1 that have deleted the r-determinants component is 0.8 X 10(6) daltons larger than fragment A of composite NR1. Only a part of fragment H of the r-determinants component is amplified in transitioned NR1 DNA in Proteus mirabilis, which consists of multiple, tandem sequences of r-determinants attached to a single copy of the RTF-TC component. Both of these changes can be explained by the locations of the excision sites at the RTF-TC: r-determinants junctions that are involved in the dissociation and reassociation of the RTF-TC and r-determinants components. The thirteen fragments of composite NR1 DNA produced by EcoRI have been ordered using partial digestion techniques. The order of the fragments is: A-D-C-E-F-B-H-I-L-K-G-M-J. The approximate locations of the TC, CM, SM/SP, and SA resistance genes on the EcoRI map were determined by analyzing several deletion mutants of NR1.
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PMID:EcoRI restriction endonuclease map of the composite R plasmid NR1. 77 43

The DNA replication origin of plasmid NR1 is located approximately 190 base pairs downstream from the 3' end of the repA1 gene, which encodes the essential initiation protein for replication of the plasmid. Restriction endonuclease fragments that contain the NR1 replication origin and its flanking sequences at circularly permuted positions were obtained by digesting oligomers of ori-containing DNA fragments with sets of enzymes that each cut only once in every ori fragment. Polyacrylamide gel electrophoresis of these permuted restriction fragments showed anomalous mobilities, indicating the presence of a DNA bending locus. Through analysis of the relative mobility plots of these permuted fragments, we found one or two possible DNA bending sites located in the intervening region between the repA1 gene and the replication origin of NR1. It seems possible that DNA bending in this region might help to orient the replication origin alongside the repA1 gene, which could contribute to the cis-acting character of the RepA1 initiation protein.
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PMID:DNA bending near the replication origin of IncFII plasmid NR1. 264 34

Drug resistance gene amplification of derivatives of plasmid NR1 having various amounts of resistance (r) determinant DNA was examined with two types of NR1 derivatives. The first was an NR1 derivative that carried two tandem copies of the r determinant component which was isolated as an intermediate in the amplification process. The plating efficiency of host cells and restriction endonuclease analysis of the plasmid DNA indicate that plasmids with two tandem copies of the r determinant undergo spontaneous amplification to a more highly amplified state at a frequency 150-fold higher than that of wild-type NR1. The second class of derivatives consisted of plasmids in which different regions of the r determinant component had been deleted. The relationship between spontaneous amplification frequency and r determinant size was examined with these plasmids. Plating efficiency of host cells indicated that plasmids with a smaller r determinant undergo spontaneous amplification at a lower frequency than do plasmids with a larger r determinant. These results suggest that there is an ordered sequence of events in the amplification of the r determinant of NR1.
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PMID:Drug resistance gene amplification of plasmid NR1 derivatives with various amounts of resistance determinant DNA. 298 82

Derivatives of the composite R plasmid NR1 from which a portion of the resistance determinants (r-determinants) component had been deleted were found to undergo amplification of the remaining r-determinants region in Escherichia coli and Salmonella typhimurium. The wild-type NR1 plasmid does not amplify in these genera, although all of these plasmids undergo amplification in Proteus mirabilis. The deletion mutants retained the mercuric ion resistance operon (mer) but conferred a much lower level of sulfonamide resistance than NR1. The remaining r-determinants region, which is bounded by direct repeats of the insertion element IS1, formed multiple tandem duplications in E. coli, S. typhimurium, and P. mirabilis after subculturing the host cells in medium containing high concentrations of sulfonamide. Gene amplification was characterized by restriction endonuclease analysis, analytical buoyant density centrifugation, DNA-DNA hybridization, and sedimentation in sucrose gradients. The tandem repeats remained attached to the resistance transfer factor component of the plasmid in at least part of the plasmid population; autonomous tandem repeats of r-determinants were probably also present. Amplification did not occur in host recA mutants. Amplified strains subcultured in drug-free medium lost the amplified r-determinants. By using a strain temperature sensitive for the recA gene, it was possible to obtain gene amplification at the permissive temperature. Loss of r-determinants took place at the permissive temperature, but not at the nonpermissive temperature. The termini of the deletions of several independent mutants which conferred low sulfonamide resistance were found to be located within the adjacent streptomycin-spectinomycin resistance gene.
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PMID:Transition of deletion mutants of the composite resistance plasmid NR1 in Escherichia coli and Salmonella typhimurium. 608 73

One approach to studying the functional role of individual NMDA receptor subunits involves the reduction in the abundance of the protein subunit in neurons. We have pursued a strategy to achieve this goal that involves the use of a small guide RNA which can lead to the destruction of the mRNA for a specific receptor subunit. We designed a small RNA molecule, termed 'external guide sequence' (EGS), which binds to the NR1 mRNA and directs the endonuclease RNase P to cleave the target message. This EGS has exquisite specificity and directed the RNase P-dependent cleavage at the targeted location within the NR1 mRNA. To improve the efficiency of this EGS, an in vitro evolution strategy was employed which led to a second generation EGS that was 10 times more potent than the parent molecule. We constructed an expression cassette by flanking the EGS with self-cleaving ribozymes and this permitted generation of the specified EGS RNA sequence from any promoter. Using a recombinant Herpes simplex virus (HSV), we expressed the EGS in neurons and showed the potency of the EGS to reduce NR1 protein within neurons. In an excitotoxicity assay, we showed that expression of the EGS in cortical neurons is neuroprotective. Our results demonstrate the utility of EGSs to reduce the expression of any gene (and potentially any splice variant) in neurons.
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PMID:Reduction of functional N-methyl-D-aspartate receptors in neurons by RNase P-mediated cleavage of the NR1 mRNA. 1123 23