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)

In 1980, the number of Shigella sonnei strains isolated in Sicily increased markedly. Approximately 80% of the isolates belonged to phage-type 3 and showed the same antibiotic resistance pattern, suggesting that an epidemic had been going on for several months. Plasmid analysis of strains isolated at various times in different places supported this view. Agarose gel electrophoresis of plasmid preparations from seven selected phage-type 3 isolates showed the presence of two plasmids, of 80 megadaltons (Mdal) and 55 Mdal, respectively. In addition, all but one harboured a 2.8-Mdal plasmid, while a 30-Mdal and a 47-Mdal plasmid were, respectively, present in two other isolates. The 80-Mdal plasmid was self-transmissible to Escherichia coli K12, which acquired "en bloc" the resistance patterns of the donor strains. All the self-transmissible R plasmids fell into the incompatibility group I1 and showed a similar endonuclease cleavage pattern. An S. sonnei strain which was isolated during the same period, but did not belong to phage-type 3, exhibited a totally different plasmid pattern. We can conclude that phage-typing and R-plasmid characterization (i.e. incompatibility group, molecular weight and endonuclease cleavage pattern) represent the most reliable methods for epidemiologic study of S. sonnei isolates.
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PMID:Epidemiological markers of Shigella sonnei infections: R-plasmid fingerprinting, phage-typing and biotyping. 390 79

The 25-kDa peptidoglycan-associated outer-membrane protein and most likely porin of Vibrio cholerae is a major immunogenic species. It has been purified by ion-exchange elution on hydroxyapatite followed by gel filtration on Bio-Gel P150 both in the presence of sodium dodecyl sulfate. This protein, of greater than 90% purity as judged by Western blotting, has been used to raise antibodies in rabbits. The antisera were then used to screen V. cholerae gene banks, constructed in Escherichia coli K12, and this has enabled us to isolate several colonies harbouring the cloned gene. The plasmids in these colonies have been designated pPM451, pPM455 and pPM472. These plasmids have a 5.3 X 10(3)-base BamHI fragment of V. cholerae DNA in common. Restriction endonuclease mapping of these plasmids has been performed and the protein identified both by Western blot analysis and in E. coli K12 minicells. The protein is not efficiently expressed in E. coli K12. It is proposed to use the name ompV to describe the structural gene, present in the cloned DNA, for this V. cholerae outer membrane protein.
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PMID:Purification of the 25-kDa Vibrio cholerae major outer-membrane protein and the molecular cloning of its gene: ompV. 398 95

Plasmid pLC1437a contains DNA from Escherichia coli K12 including fol, the structural gene for dihydrofolate reductase. The fol gene was mapped on this plasmid relative to several restriction endonuclease cleavage sites. fol was also cloned from strain RSO and the nucleotide sequence for the entire fol gene and its flanking regions from this strain was determined. The amino acid sequence predicted from the nucleotide sequence differs in only a few respects from the reported amino acid sequence of dihydrofolate reductase from E. coli B. The major RNA transcripts initiated at the fol promotor in vivo are approximately 550 and 590 nucleotides long. In addition to these, several longer transcripts (up to 1400 nucleotides) are present in lesser amounts. A new procedure is described for 3' end labeling of DNA fragments having blunt ends using E. coli exonuclease III and avian myeloblastoma virus reverse transcriptase.
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PMID:Nucleotide sequence of the E coli gene coding for dihydrofolate reductase. 615 75

A mutant of Escherichia coli K12, highly resistant to ultraviolet radiation, has been isolated. Preliminary tests show that this mutant is also resistant to mitomycin C, nalidixic acid, fluorouracil and thymineless death. The mutant strain apparently repairs its damaged DNA more efficiently than wild-type E. coli K12 strains and, to do so, constitutively produces 35 times more DNA polymerase I and 12 times more endonuclease I than the wild-type strain.
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PMID:Isolation and characterization of a mutant of Escherichia coli K12 synthesizing DNA polymerase I and endonuclease I constitutively. 625 82

lambda qsr' (Q-independent) phages are characterised by the replacement of the region of the lambda genome that contains Q, S, R, and the late gene promoter, P'R, with host-derived DNA that codes for functions analogous to those deleted. Restriction endonuclease analysis and DNA/DNA hybridisation methods have been used to show that lambda p4 and lambda qin A3, two such Q-independent phages, are the product of recombination between lambda and a defective lambdoid prophage (the qsr' prophage) located at an as yet unidentified site in the E. coli K 12 chromosome. The qsr' prophage is distinct from the defective lambdoid prophage Rac (Kaiser and Murray 1979). In the E. coli K12 strain AB1157 from which lambda qsr' phages cannot be generated, the qsr' prophage has suffered an internal deletion. That the qsr' prophage appears not to carry a full complement of essential late genes suggests one explanation for its apparently defective nature.
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PMID:The origin of Q-independent derivatives of phage lambda. 625 85

The involvement of the transposable DNA element of E. coli K12 chromosome in integrative recombination of RP1 plasmid was studied. Using temperature sensitive for replication plasmid RP1ts12--the derivative of RP1 which contains mutated transposon Tnl, it was shown that integration of RP1 into host chromosome and Hfr formation may occur according to a mechanism mediated by chromosome IS-elements. Plasmids that are desintegrated from the chromosome of these Hfrs contain discrete DNA segments (IS-elements) and possess elevated frequency of integration into chromosome of rec+ cells. The latter was used for selection of RP1ts12 recombinants carrying chromosome IS. For identification of IS involved in RP1 integration the number of independent RP1ts 12 recombinants was subjected to restriction and heteroduplex analysis. By analysing recombinants integrated into bacterial chromosome with frequency 5 X 10(-3), a new IS-element of E. coli K12 designated IS111 was discovered. IS111-element is about 1500bp of length, contains Smal, Pst1 and BamH1 restriction endonuclease sites and was found in the same position on the plasmid RP1 in two different orientations. IS-elements that have been revealed in a number of other RP1ts12 recombinants were preliminary identified as IS1-like elements. One recombinants plasmid was found to have an IS5-like elements. The activity of IS-elements inserted into RP1ts12 in recA-dependent integrative recombination was estimated. From the data of absolute and relative RP1ts12 integration frequencies mediated by IS111, IS1- and IS5-like elements a conclusion was made about the absence of E. coli K12 chromosome IS-elements in RP1 plasmid. The Hfr-formation and chromosomal gene transfer by recombinant plasmids RP1ts12: IS111 were studied. The possibility to use insertion RP1ts12 derivatives for the estimation of copies number, mapping and definition of orientation of IS-elements in bacterial chromosome and the possibilities for detection of transposable DNA elements using RP1ts12 in a wide range of gram-negative bacteria are discussed.
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PMID:[Thermosensitive vector derived from RP1 plasmid for detection of transposable elements]. 628 85

A DNA duplex coding for the 53 amino acids of human beta-urogastrone has been synthesised. Computer assisted design of the gene included restriction endonuclease sites for plasmid insertion, a termination codon and two triplets coding for lysine at the 5'-end of the structural gene. The synthesis involved preparation of 23 oligodeoxyribonucleotides by phosphotriester procedures coupled to rapid HPLC techniques. The gene was constructed in two halves by enzymatic ligation of the oligonucleotides and cloned into a specially constructed chimeric plasmid vector. Escherichia coli K12 MRC8 was transformed by the plasmid and clones containing the full gene sequence were isolated and characterised.
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PMID:Chemical synthesis and cloning of a gene for human beta-urogastrone. 629 Sep 82

A lysogen of Escherichia coli K12 with lambda cI857 S7 xis6 nin5 b515 b519 integrated into ptsI was induced and the lysates plated on a Pel- host [on which lambda strains with less than the wild-type amount of DNA form plaques at low frequency (Cameron et al., 1977)]. All of the 40 plaques examined contained phage able to transduce at least two of the genes known from bacteriophage P1 transduction experiments to be closely linked to ptsI. Assuming that each specialized transducing phage arose by a single illegitimate recombination event, the distribution of phage types showed that the gene order is cysA gsr ptsI (ptsH, iex) cysZ lig; both gsr+ and iex+ were dominant. Analysis of restriction endonuclease digests of the transducing phage confirmed that no unexpected DNA rearrangements had taken place and allowed the construction of a map of the sites of action of the restriction endonucleases EcoRI, HindIII, BamI and Kpn for over 20 kilobases of E. coli DNA. In an Appendix, we show cysA and cysZ mutants to be deficient in sulphate assimilation.
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PMID:Phosphotransferase-mediated regulation of carbohydrate utilization in Escherichia coli K12: location of the gsr (tgs) and iex (crr) genes by specialized transduction. 630 2

Employing the recombinant runaway replication plasmid pDPK13 [sbcB+], an exonuclease I-overproducing derivative of Escherichia coli K12 has been constructed. The strain SK4258 has exonuclease I activity 140-400-fold higher than wild type control levels. A new purification procedure has been developed such that the protein can be purified to near homogeneity and is free of endonuclease and RNase activities. The specific activity of the purified enzyme is 10-fold higher than reported previously (Ray, R.K., Reuben, R., Molineux, I., and Gefter, M. (1974) J. Biol. Chem. 249, 5379-5381). Native exonuclease I is a single polypeptide having Mr = 55,000 with a Stokes radius of 3.12 nm.
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PMID:Amplification and purification of exonuclease I from Escherichia coli K12. 634 75

A lambda transducing phage carrying the traGSTD genes of the E. coli K12 factor F was isolated by an in vivo technique, and characterized in tra complementation tests, by determining its restriction endonuclease fragment sizes, and by measuring heteroduplex molecules. The size and location on the F physical map of the tra transducing segment was thereby determined. Comparison of the proteins synthesized in UV-irradiated cells by this phage and by a derivative carrying the amber traG79 mutation, allowed the traG product to be identified as a protein of molecular weight 100,000. In the same experiments, the sizes of the traT and traD products made by the phage were also measured, being 25,000 and 85,000 daltons respectively.
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PMID:Characterisation of a lambda transducing phage carrying the F conjugation gene traG. 644 56


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