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:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The hybrid plasmid pYBP2 with bacterial (ampR), yeast (LEU2) and bacteriophage T4 (denV) genes has been constructed. The plasmid transformed Escherichia coli CSR603 uvrA recA ampS leuA phr- to ampicillin resistance, leucine independence, UV-resistance similar to the one of uvrA+ recA strain. Cell-free extracts of transformed Escherichia coli cells contain low level of ultraviolet-endonuclease activity in contrast to nontransformed cells containing no enzyme.
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PMID:[Hybrid plasmid with bacterial and fungal markers carrying the denV gene of T4 phage and restoring the UV-resistance of E. coli uvrA]. 391 17

Chromosomal DNA from a uropathogenic strain of Escherichia coli was partially digested with the restriction enzyme EcoRI. The partial digests were ligated into a cosmid containing an ampicillin-resistant determinant and packaged into lambda phage particles. An ampicillin-resistant transductant of E. coli HB101 was found to possess mannose-resistant hemagglutinating activity associated with a 50-kilobase-pair plasmid. Subcloning of the mannose-resistant fimbrial genes revealed that the genetic determinants were encoded by a 6.9-kilobase-pair DNA fragment of a recombinant plasmid. Chimeric plasmids smaller in size were unable to transform E. coli to fimbrial production. Physical maps of the recombinant plasmids were prepared showing restriction endonuclease sites within the inserted DNA fragments. The hemagglutinating activities of the wild-type strain and of the recombinant derivative were compared. Both strains agglutinated human erythrocytes in the presence of D-mannose to the same degree and also failed to produce fimbriae after incubation at 18 degrees C. Also, both strains were agglutinated by antifimbrial serum at a high titer, whereas no such activity was observed when a strain of E. coli which did not possess a plasmid was used.
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PMID:Cloning of genes determining the production of mannose-resistant fimbriae in a uropathogenic strain of Escherichia coli belonging to serogroup O6. 612 10

The sites of cleavage on the map of the broad-host-range plasmid RK2 (56 kilobases) were determined for the BglII, PstI, and SmaI restriction enzymes, and the determinants for tetracycline and ampicillin resistance were localized. The cleavage sites were clustered at or near the drug resistance genes. To localize regions required for plasmid replication and maintenance in Escherichia coli, we deleted nonessential regions of RK2 by partial digestion with the restriction endonuclease HaeII to produce small derivatives. The smallest stable replicon obtained contained five HaeII fragments of RK2 which total 5.4 kilobases. These fragments were derived from three regions of RK2 that are separated from each other by antibiotic resistance genes. One of these HaeII fragments (0.75 kilobases) has the properties expected of the origin of replication. The outer four fragments, located in two separate regions of RK2, were found to provide, in trans, functions that permit the replication of the HaeII fragment carrying the origin of the replication. These results indicate that at least two plasmid-encoded genes, capable of acting in trans, and a replication origin are required for RK2 replication and maintenance.
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PMID:Regions of broad-host-range plasmid RK2 which are essential for replication and maintenance. 624 21

During an epidemic of infections at the Seattle Veterans Hospital, Washington, due to a multiresistant strain of Serratia marcencens, other enteric species were isolated that had antibiograms nearly identical to those of the epidemic S. marcescens. In 11 instances, these multiresistant species were isolated from specimens that also contained the epidemic serratia strain. All isolates of the epidemic serratia strain contained a conjugative 45-megadalton R-factor (pLST1000) coding for intermediate resistance to three amino-glycosides (minimal inhibitory concentrations, 4--8 micrograms/ml) and high-level resistance to ampicillin, carbenicillin, cephalothin, streptomycin, and sulfonamide. With the use of agarose gel electrophoresis and restriction endonuclease cleavage patterns after digestion with EcoRI, BamH1, and HindIII, it was determined that eight different enteric strains of six different species isolated from the patients contained an R-factor that was molecularly identical to the one isolated from the epidemic strain of S. marcescens. Thus, the epidemic of multiresistant infections at this hospital was caused both by the spread of an epidemic strain and an "epidemic plasmid." The molecular characteristics of pLST1000 appear to be different from previously described multiresistant plasmids.
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PMID:Molecular analysis of R-factors from multiresistant nosocomial isolates. 624 81

In vitro recombinant DNA experiments involving restriction endonuclease fragments derived from the plasmids pBR322 and pBR325 resulted in the construction of two new cloning vehicles. One of these plasmids, designated pBR327, was obtained after an EcoRII partial digestion of pBR322. The plasmid pBR327 confers resistance to tetracycline and ampicillin, contains 3273 base pairs (bp) and therefore is 1089 bp smaller than pBR322. The other newly constructed vector, which has been designated pBR328, confers resistance to chloramphenicol as well as the two former antibiotics. This plasmid contains unique HindIII, BamHI and SalI sites in the tetracycline resistance gene, unique PvuI and PstI sites in the ampicillin resistance gene and unique EcoRI, PvuII and BalI sites in the chloramphenicol resistance gene. The pBR328 plasmid contains approx. 4900 bp.
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PMID:Construction and characterization of new cloning vehicles. IV. Deletion derivatives of pBR322 and pBR325. 624 30

Double-stranded cDNA sequences were synthesized, by using as templates mRNA for alpha and beta subunits of thyrotropin purified from mouse thyrotrophic pituitary tumours and cloned in Escherichia coli RR1 by insertion in the Pst I site of the bacterial plasmid pBR322 by use of poly(dA) x poly(dT) homopolymeric extensions. Plasmids containing inserted cDNA sequences were selected by resistance to tetracycline and sensitivity to ampicillin; those containing thyrotropin cDNA sequences were identified by colony hybridization with an 125I-labeled mixture of alpha and beta thyrotropin mRNAs. Plasmids carrying either alpha or beta thyrotropin cDNA sequences were further identified by hybridization to highly purified 125I-labeled alpha or beta thyrotropin mRNA, respectively. Two plasmids, one containing a 400-nucleotide alpha thyrotropin cDNA insert and the other containing a 710-nucleotide beta thyrotropin cDNA insert, were purified and characterized by restriction endonuclease digestions. Plasmid [32P]DNA containing either alpha or beta thyrotropin cDNA was then used as a hybridization probe for further characterization of alpha and beta thyrotropin mRNA from the mouse thyrotropic tumor. RNA was fractionated by agarose gel electrophoresis under denaturing and nondenaturing conditions and transferred to diazobenzyloxymethyl-paper. alpha thyrotropin mRNA of two sizes, 650 and approximately equal to 1500 nucleotides long, were identified. The larger alpha thyrotropin mRNA appeared to have marked secondary structure in its native form in contrast to the 650-nucleotide alpha thyrotropin mRNA. However, only one form of beta thyrotropin mRNA was detected with an apparent size of 710 nucleotides. We have successfully cloned and identified alpha and beta thyrotropin cDNA sequences in bacterial plasmids and used them to identify a second form of alpha thyrotropin mRNA.
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PMID:Synthesis, cloning, and identification of DNA sequences complementary to mRNAs for alpha and beta subunits of thyrotropin. 625 47

In an Escherichia coli strain of human origin, ampicillin resistance and heat-stable enterotoxin activity were shown by EcoRI restriction endonuclease and genetic analysis to be in an 80-megadalton plasmid.
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PMID:Linkage of heat-stable enterotoxin activity and ampicillin resistance in a plasmid isolated from an Escherichia coli strain of human origin. 625 90

Secondary attachment site lambda-lysogens were isolated in an Escherichia coli strain carrying multiple tandem 9.8 kb repeats. The repeat carried the structural gene for chromosomal beta-lactamase, ampC. One lysogen produced lysates with amp-transducing activity. Three types of phages with different densities were obtained from this lysogen. The one with the lowest density was found to be a helper lambda cI857S7 phage. The other two phage showed identical restriction endonuclease fragmentation patterns. The difference in density was due to the presence or absence of phage tail. In lambda damp the right cohesive end segment was deleted in a random fashion with the majority ending between 81.0% and 82.4% of lambda. The chromosomal segment of lambda damp was most likely located at the lambda attachment site. The lambda damp DNA was compared to that of ColE1 hybrid carrying the chromosomal amp segment and a ColE1 hybrid carrying the same 9.8 kb amp repeat as the lysogen from which lambda damp was isolated. It was found that the chromosomal part of lambda damp constituted 9.8 kb, i.e. the size of one repeat. Moreover, the novel joint between adjacent repeats was present. In a lambda attB-deleted E. coli K-12 strain, lysogenic for lambda damp, highly ampicillin-resistant mutants occurred at an exceedingly high frequency. They were found to contain in the chromosome an amplified 9.8 kb repeat. This suggested that integration of the novel joint for lambda damp into the amp region gives rise to an amplifiable duplication. In E. coli lysogenized for lambda damp at lambda attB highly ampicillin-resistant clones were also found at a high frequency. These clones carried multiple tandem repeats of lambda damp DNA, each with an intact right end segment.
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PMID:Tandem duplication induced by an unusual ampA1-, ampC-transducing lambda phage: a probe to initiate gene amplification. 625 21

This paper reports the cleavage maps of ampicillin transposons Tn2601 and Tn2602, for restriction endonucleases BamHI, PvuII, AvaI, HincII, and HaeII. Both of the transposons are very similar to the well-known ampicillin transposon Tn3 in size, endonuclease cleavage sites, and possession of a short inverted repeat sequence at both ends. A slight difference in the cleavage pattern among these three transposons was observed in the region around the BamHI site which was assumed to be a part of the repressor gene for transposition.
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PMID:Restriction endonuclease cleavage maps of the ampicillin transposons Tn2601 and Tn2602. 626 Oct 93

Tightly membrane-bound polysomes were isolated from livers of rats administered trans-stilbene oxide. Epoxide hydratase mRNA was enriched from these polysomes using immunochemical techniques and oligo(dT)-cellulose chromatography. This resulted in an increase in message concentration over that found in noninduced membrane-bound cDNA, synthesized from enriched mRNA, was inserted into the ampicillin resistance gene of pBR322 using oligo(dG)-oligo(dC) tailing. Clones containing sequences complementary to epoxide hydratase mRNA were selected by differential colony hybridization using [32P]cDNA synthesized from immunoenriched mRNA and [32P]cDNA synthesized from nonenriched mRNA. Plasmids from four clones, which only annealed with the enriched probe, were isolated and shown to specifically hybridize with epoxide hydratase mRNA by hybrid selection-translation. A composite restriction endonuclease map of the plasmid inserts was constructed which spanned 1310 base pairs and represented approximately 80% of the message sequence. The 3'-5' orientation of this map relative to the epoxide hydratase mRNA was also determined.
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PMID:Cloning of epoxide hydratase complementary DNA. 626 98


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