Biomedical subjects
Publications and source records attributed to N I Matvienko.
The authors elaborated a method of isolation of high molecular DNA from the plasmids FB1 and FB1drd of the conditionally pathogenic E. coli strains. Molecular weights of the isolated plasmid DNAs were determined by means of electrophoresis of the DNA fragments in agar gel and sedimentation in the neutral gradient of glycerine concentration.
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In vitro repair of single strand breaks in T4 and phage DNA caused by 32p decay was studied. Zone centrifugation procedure showed that polynucleotide kinase, ligase enzyme system failed to repair 32P-damages. It was found that damaged DNA contained gaps and could be repaired by DNA-polymerase I, polynucleotide ligase treatment.
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Hershey circles and linear tandem aggregated forms of DNA have been obtained in vitro and treated with polynucleotide ligase to form phosphodiester bond. Using zone centrifugation in glycerol gradient covalently closed circles and linear dimers have been purified and their biological activity investigated. It was found that closed circular molecules lost most, if not all, of their activity in CaCl2-dependent system. In order to investigate the biological activity of tandem dimer molecules, hybrid dimers consisting of DNA's from lambda C1857 and lambda 1434 have been obtained. In plaque assay with the appropriate non-permissive strains of E. coli the efficiency of infectivity of hybrid dimers was measured. Biological activity of dimer molecules sealed with ligase was about 5% of the activity of linear monomers. Ig has been suggested that tandem dimers of lambda DNA joined by phosphodiester bond are able to penetrate into the CaCl2-treated host cells and both components of dimers are active during subsequent multiplication.
The deletions in tandem prophage lambda appear with high frequency (to 10%) in rec A- strain of Escherichia coli. The deletions were shown by marker rescue and hybridization of fragments of DNA on nitrocellulose filters with nick-translated phage lambda DNA localized only in prophage area. Right and left att sites are not involved. The majority of defective lysogens had all regulatory regions and deletions of late structural genes. These strains may be used for construction of the host-vector systems with the strongest promoter p'R of phage lambda.
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The strain, producing new site-specific endonuclease BcoKI has been found at the screening of the thermophilic bacteria isolated from tobacco. A phenotype characteristic of the strain is given. It has been identified as a new strain Bacillus coagulans. BcoKI, a class-IIS restriction endonuclease has been obtained by three consecutive chromatographies on blue agarose hydroxyapatite and heparin-Sepharose. BcoKI, an isoschizomer of Ksp6321, recognizes the six base non-palindromic sequence 5'CTCTTC3' and cleaves one nucleotide 3' of the 3' cytosine on this strand and four nucleotide 5' of the 5' guanine on the opposite strand to generate a three base 5' overhang.
The restriction map of the nuclear polyhedrosis DNA virus of Bombyx mori has been determined with the use of four restriction endonucleases: NotI, BamHI, SmaI and KpnI. 18 cleavage sites have been localized on the viral DNA. Total length of the viral DNA is about 130 kb. The fragment containing a polyhedrin gene has been localized on the map by the blot hybridization technique.
A new restriction endonuclease BstBSI was isolated and purified from the thermophilic soil bacterium Bacillus stearothermophilus BS by the blue sepharose and hydroxyapatite chromatographies. The enzyme is an isoschizomer of SnaI from Sphaerotilus natans C. It recognizes the hexanucleotide GTATAC and cleaves DNA in the center of the sequence. The maximal catalytic activity of the endonuclease is registered in 50 mM tris-HCl (pH 9.0) buffer with the high ionic strength (100 mM NaCl) in the presence of 10 mM MgCl2 at 45 degrees C. Glucosylated DNA of the phage T4 is not cleaved by the enzyme.