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A Piekarowicz

Publications and source records attributed to A Piekarowicz.

At least 37 records · Page 2Linked to original sources
PubMed1991

Isolation of temperature-sensitive McrA and McrB mutations and complementation analysis of the McrBC region of Escherichia coli K-12.

We isolated temperature-sensitive mcrA and mcrBC mutants of Escherichia coli. At 42 degrees C, they were unable to restrict the T-even bacteriophages T6gt and T4gt or plasmids encoding cloned DNA methylase genes whose specificities confer sensitivity to the McrA and McrBC nucleases. Complementation analysis of the McrBC region (mcrB251) with the complete cloned McrBC system or a derivative with mcrB alone indicated that the mutation shows an absolute defect for the restriction of DNA containing hydroxymethylcytosine and a thermosensitive defect for the restriction of DNA containing methylcytosine. The properties of the McrA temperature-sensitive mutants suggest that some of these mutations can also influence the restriction of DNA containing hydroxymethylcytosine or methylcytosine residues.

Chromosomes, Bacterial↗
PubMed1991

Nomenclature relating to restriction of modified DNA in Escherichia coli.

At least three restriction systems that attack DNA containing naturally modified bases have been found in common Escherichia coli K-12 strains. These systems are McrA, McrBC, and Mrr. A brief summary of the genetic and phenotypic properties so far observed in laboratory strains is set forth, together with a proposed nomenclature for describing these properties.

Alleles↗
PubMed1989

The EcoDXX1 restriction and modification system: cloning the genes and homology to type I restriction and modification systems.

The Escherichia coli plasmid pDXX1 codes for a type I restriction and modification system, EcoDXX1. A 15.5-kb BamHI fragment from pDXX1 has been cloned and contains the hsdR, hsdM, and hsdS genes that encode the EcoDXX1 system. The EcoDXX1 hsd genes can complement the gene products of the EcoR124 and EcoR124/3 hsd systems, but not those of EcoK and EcoB. Hybridization experiments using EcoDXX1 hsd genes as a probe demonstrate homology between EcoDXX1 and EcoR124 and EcoR124/3 restriction-modification systems, but weak or no homology between EcoDXX1 and EcoK or EcoB systems.

Blotting, Southern↗
PubMed1989

Transfer of plasmid Hly in vivo in pigs intestine.

The results of our study suggest the in vivo transfer of Hly plasmid from native pathogenic and enterotoxigenic Escherichia coli strain to autochtonous Escherichia coli, using ileal loop test. To confirm this hypothesis pHly::Tn5 and PHly::Tn3 were obtained using an in vitro recombination method, and introduced to Escherichia coli laboratory strain. For experiments the laboratory strain, carrying pHly::Tn5 and pHly::Tn3 and pHly::Tn5 strain which acquired K88(F4) by means of conjugation, were used. In the study in which the donor Escherichia coli pHly::Tn5 strain, carrying antigen K88(F4), was injected into the ileum, pHly conjugants were isolated from faeces after 48 h in 2 out of 5 pigs, which was a low frequency. After the oral introduction of 10(9) cells of pHly::Tn5 and pHly::Tn3 Escherichia coli strains without the colonizing factor K88(F4), conjugants were not isolated from faeces of experimental animals. However when the pigs received donor CSH55 pHly::Tn5 Escherichia coli strain orally, which were also carrying plasmid K88(F4), transconjugants were obtained in a low frequency of 3 out of 9 pigs. Our experiments confirmed the suggestion of Smith that in vivo transfer of plasmid in the intestine of animals is only possible when the donor transfers the plasmid with high frequency and readily colonizes the intestine. The pHly::Tn5 plasmid acquired by in vitro recombination does not spread with time throughout the autochtonic population of Escherichia coli present in the intestine of swine. The results of our study showed the in vivo transfer in pigs intestine of Hly pathogenicity marker from both native pathogenic strains carrying antigen K88(F4) and constructed donor laboratory strain of Escherichia coli pHly::Tn5 also carrying antigen K88(F4) to autochtonous intestinal strains.

Animals↗
PubMed1988

Neisseria gonorrhoeae M.Ngo AI DNA methyltransferase: physical and catalytic properties of the homogeneous enzyme.

A DNA methyltransferase, M.NgoAI, was purified to homogeneity from Neisseria gonorrhoeae strain WR220 by successive column chromatography. Its Mr is 25,000, as determined by both gel filtration and denaturing polyacrylamide gel electrophoresis. Maximal enzymatic activity was obtained in 50 mM Tris.HCl (pH 7.4), 10 mM EDTA, with incubation at 37 degrees C. An apparent Km value for S-adenosylmethionine and 5' -GGCC sites was determined to be 1.25 microM and 89.6 nM, respectively.

Bacterial Proteins↗
PubMed1988

Purification and characterization of DNA methyltransferases from Neisseria gonorrhoeae.

Three DNA methyltransferases, M.NgoAI, and M.NgoBI and M.NgoBII, free of any nuclease activities were isolated from Neisseria gonorrhoeae strains WR220 and MUG116 respectively. M.NgoAI recognizes the sequence 5' GGCC 3' and methylates the first 5' cytosine on both strands. M.NgoBI and M.NgoBII recognize 5' TCACC 3' and 5' GTAN5CTC 3' respectively. M.NgoBII methylates cytosine on only one strand to produce 5' GTAN5mCTC 3'.

Cytosine↗
PubMed1988

Restriction of plasmid DNA during transformation but not conjugation in Neisseria gonorrhoeae.

Neisseria gonorrhoeae strains WR302 and PGH3-2 were characterized with respect to their restriction-modification phenotype. WR302 DNA was cleaved by HaeIII, indicating the lack of methylation at the GGCC sequence. PGH3-2 produced NgoSI (an isoschizomer of NgoII). WR302 produced a restriction enzyme with a recognition sequence different from that of NgoI, NgoII, or NgoIII. Plasmid pFT180 isolated from WR302 was unable to transform PGH3-2, whereas plasmid pFT180 isolated from PGH3-2 was able to transform PGH3-2 at a very high frequency. When plasmid pFT180 isolated from WR302 was methylated in vitro with meth M. HaeIII, this plasmid was able to transform PGH3-2. NgoSI was able to restrict WR302 DNA in vitro, whereas it was incapable of restricting PGH3-2 DNA in vitro. When the self-transmissible R factor pFT6 was mobilized from WR302 to PGH3-2 by conjugation, a 1-order-of-magnitude difference in transfer frequencies was observed, as compared with an isogenic cross. The data indicate that host-mediated restriction can prevent the gonococcus from acquiring DNA via transformation but not via conjugation.

Conjugation, Genetic↗
PubMed1986

The DNA sequence recognized by the EcoDXX1 restriction endonuclease.

EcoDXX1 is a type-I restriction enzyme coded for by the plasmid pDXX1. Like other type-I restriction endonucleases, the enzyme catalyses the modification of susceptible DNA. We have determined the DNA sequence recognised by EcoDXX1 to be: 5'TCANNNNNNNATTC-3' 3'-AGTNNNNNNNTAAG-5' where N can be any nucleotide. This sequence has an overall structure very similar to previously determined type-I sequences.

Bacteriophage phi X 174↗
PubMed1986

Major spontaneous genomic rearrangements in Haemophilus influenzae S2 and HP1c1 bacteriophages.

Physical maps constructed by the localization of the cleavage site of several restriction endonucleases have shown that the genomes of the Haemophilus bacteriophages S2 and HP1c1 exist in variant forms which differ in the molecular organization of the genomes. At least three regions of different organization of the bacteriophage chromosomes have been identified. The different types of molecular organization can be detected both in the DNA isolated from the mature phage particles and after integration of the phage DNA into the bacterial chromosome.

Bacteriophages↗
PubMed1986

Restriction mapping and close relationship of the DNA of Streptomyces erythraeus phages 121 and SE-5.

The biological properties and genome structure of two actinophages, 121 and SE-5, infecting Streptomyces erythraeus were characterized. They had the same host range (limited to S. erythraeus) and similar DNA G + C contents (around 60 mol %). Restriction maps of their genomes also showed many similarities. The close relationship between the two phages was confirmed by DNA hybridization experiments: large parts of their genomes were homologous, except for a segment in the middle of the map, where no hybridization was detected.

Bacteriophages↗
PubMed1986

Comparison of HP1c1 and S2 phages of Haemophilus influenzae.

Physical maps constructed by localization of the cleavage sites of several restriction endonucleases have shown that the chromosome of Haemophilus influenzae bacteriophage S2 and HP1c1 can possess different types of molecular organization (Piekarowicz, Brzezinski, Smorawinska, Kauc, Skowronek, Lenarczyk & Gołembiewska, 1986). We have compared the physical maps of the HP1c1 and S2 phage DNAs of type B and the results led us to conclude that there are no differences between these two phages of the same type of molecular organization of the genomes, i.e. S2 and HP1c1 is the same phage. We also suggest that some of the fine differences between these two phages noted in some laboratories were induced only by different type of genome of the same phage.

Bacteriophages↗
PubMed1985

The EcoDXX1 restriction and modification system of Escherichia coli ET7. Purification, subunit structure and properties of the restriction endonuclease.

The Escherichia coli plasmid pDXX1 codes for a new restriction-modification system. The specific restriction endonuclease coded by this system has been purified by a procedure that includes phosphocellulose and heparin-agarose chromatography. Sedimentation on glycerol gradients showed one peak of activity with a value of about 12 S. The highly purified enzyme require ATP and Mg2+ for activity as well as S-adenosylmethionine, although some S-adenosylmethionine molecules are probably bound to the enzyme. The enzyme does not cleave lambda DNA at well-defined sites and has a strong non-modified DNA-dependent ATPase activity. The enzyme has also methylase activity acting against non-modified DNA.

Adenosine Triphosphatases↗
PubMed1984

Preferential cleavage by restriction endonuclease HinfIII.

The efficiency of endonucleolytic scission by restriction endonuclease HinfIII varies markedly for different recognition sites. The relative frequencies of cleavage at these sites have been determined on the basis of analysis of specific unit length linear molecules formed. The efficiency of restriction reaction depends also on the number of recognition sites in the DNA substrate. Cleavage by HinfIII in the absence or presence of S-adenosylmethionine is observed only when at least three recognition sites are present. HinfIII also shows preferential methylation of certain sites observable even for a substrate with one recognition site. The nucleotide sequences at sites cleaved or methylated at high frequency have been compared.

Base Sequence↗
PubMed1983

Isolation and characterization of Streptomyces erythreus plasmids.

Streptomyces erythreus strains were found to carry several plasmids of molecular weights ranging from about 2 X 10(6) Mr to 40 X 10(6) Mr. Restriction enzyme maps for the streptomycete plasmids pPC7 and pPC8 were constructed for the enzymes Bg/II, EcoRI, XbaI, HindIII, BamHI and SalI. The smaller, pPC8, plasmid appears to be a naturally occurring deletion variant of pPC7. These plasmids belong to the group of conjugative streptomycete plasmids.

Culture Media↗