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Biomedical subjects

A S Solonin

Publications and source records attributed to A S Solonin.

At least 37 records · Page 2Linked to original sources
PubMed1981

Overproduction of the EcoRII endonuclease and methylase by Escherichia coli strains carrying recombinant plasmids constructed in vitro.

Recombinant DNA molecules were constructed from the plasmid pIL203 and the EcoRI-fragment of N3 plasmid containing EcoRII endonuclease and methylase genes and also a gene for resistance to sulfanilamide. The pIL203 plasmid, used as a vector, consisted of the Bam HI-EcoRI-fragment of the plasmid pBR322 conferring resistance to ampicillin and the Bam HI-EcoRI-fragment of lambda phage containing promoters, a thermosensitive mutation in the cI gene and a suppressible amber mutation in the cro gene. Ampicillin-sulfanilamide-resistant clones were selected and tested for their restriction and modification phenotype. The recombinant plasmid DNA, isolated from ApRSuR-resistant clones, which restricted and modified phage lambda imm21 with EcoRII specificity, had the EcoRI-fragment with EcoRII genes in a single orientation. The recombinant plasmid pSK323 was transferred into E. coli strains with su-, su1, su2 or su3 phenotypes. The synthesis of products of EcoRII genes by these strains grown at 37 degrees C is increased by 10--50-fold.

Cloning, Molecular↗
PubMed1981

Cloning of a recA-like gene of Proteus mirabilis.

A gene of Proteus mirabilis that can substitute for functions of the recA gene of Escherichia coli has been cloned into the plasmid pBR322, using shotgun experiments. The recA-like gene (recAp.m.) has been localized by restriction mapping within a 1.5-Md PstI fragment that is a part of two cloned HindIII fragments of the chromosome of P. mirabilis. The restriction map of the recAp.m. gene differs from that of the recA gene of E. coli. Functionally, the recombinant plasmids containing the recAp.m. gene restore a nearly wild-type level of UV-resistance to several point and deletion mutants in the recA gene of E. coli.

Chromosome Mapping↗
PubMed1976

Construction of a hybrid col E1 plasmid carrying the gene for bacteriophage lambda repressor.

A biologically active hybrid DNA molecule was constructed from plasmid Col E1 and the Eco R1 fragment of lambda DNA containing the gene for lambda repressor. The presence of this gene in the hybrid molecule was demonstrated genetically. The hybrid plasmid contains two closely located targets for restriction endonuclease Hind 111 in the integrated fragment. Thus, the plasmid may be used as a vector not only for Eco R1 fragments but also for Hind 111 fragments.

Colicins↗
PubMedDate not supplied

[Restriction endonucleases from various bacterial strains exhibit an ice-nucleating activity].

Six strains containing site-specific endonucleases II were selected from a collection of 45 ice-nucleating bacterial strains isolated from rhizosphere of plants growing in various geographical regions. Endonucleases Pfl211I, Psp8I, and Psp23I were isolated and purified from two Pseudomonas sp. strains and a Pseudomonas fluorescens strain. Restriction endonucleases Pfl21I and Psp23I were shown to recognize and cleave the DNA nucleotide sequence 5'-CTGCA decrease G-3'. Endonuclease Psp8I recognized and cleaved the DNA nucleotide sequence 5'-G decrease GATCC-3'. These endonucleases were found to be true isoschizomers of PstI and BamHI, respectively.

Bacterial Proteins↗
PubMedDate not supplied

[Selection and some properties of recombinant clones of lambda bacteriophage containing structural genes of Drosophila melanogaster].

The lambdagt clones containing fragments of D. melanogaster genome were prepared and characterized by hybridization of their DNA with complementary RNA synthesized on the lambdagt DNA, C fragment of lambdagt DNA and total D. melanogaster DNA, and also with mRNA and a stable cytoplasmic poly(A)-RNA both isolated from D. melanogaster cells grown in culture. The technique for a simple selection of hybrid clones is described. The hybridization with mRNA allows one to select the clones containing structural genes of D. melanogaster. It was found that in all cases when the clone contains the structural gene it also contains the reiterated base sequences of the D. melanogaster genome. Several clones containing D. melanogaster DNA fragments with a size of (2--4) X 10(6) daltons which hybridized with a relatively large portion of mRNA were selcted for further analysis.

Animals↗
PubMedDate not supplied

[Plasmid localization and cloning of restriction modification genes from Citrobacter freundii 4111 strain].

Over 60 producing strains of restriction endonucleases type II have been found among 500 different strains, mostly Enterobacteriaceae. The strain Citrobacter freundii 4111 produces restriction endonuclease CfrBI, a new isoschisomer of StyI. The genes of the restriction-modification system CfrBI were located on the multicopy plasmid pZE8 containing the Co1E1-type replicon and cloned to E. coli K802. The deletion variant of 3.2-kb pZE8 which contains intact restriction-modification and a DNA fragment responsible for autonomous plasmid replication was selected among the recombinant plasmids. The strain with higher R. CfrBI production (at least 10,000,000 U/g cells, which is 500-fold higher than the wild strain) was constructed.

Citrobacter freundii↗
PubMedDate not supplied

[Laccase of the lignolytic fungus Trametes hirsuta: purification and characterization of the enzyme, and cloning and primary structure of the gene].

The main physicochemical characteristics of the major isoform of the laccase secreted by the fungu, Trametes hirsuta 072 were studied. The enzyme belongs to the group of high redox potential laccases (E(T1) = 790 +/- 5), and it oxidizes with high efficiency various substrates of phenolic nature. The gene of this isoform was cloned, and its nucleotide sequence was determined. The length of the complete gene is 2134 bp. It comprises 11 exons and 10 introns. Analysis of the amino acid sequence of T. hirsuta 072 laccase demonstrated a high homology (to 96.9%) to the other laccases secreted by fungi of the genus Trametes.

Amino Acid Sequence↗
PubMedDate not supplied

[Properties of the replicator region of the natural plasmid pLG13 containing genes of the EcoRV restriction-modification system].

The previously constructed plasmid pILRV8 that induces endonuclease EcoRV gene overexpression kills cells of some E. coli strains under the induction of this enzyme synthesis. Cell transformation by natural plasmid pLG13 carrying genes of the EcoRV restriction--modification system was found to appreciably enhance cell viability ("survival") under endonuclease overproduction. A plasmid pLG13 region located in immediate proximity to the methylase gene was shown to be responsible for the above effect. This region was also capable for autonomous replication. The analysis of the DNA primary structure in the found replicator region allowed to refer the pLG13 to ColE1 family plasmids. Perturbations in the region lead to loss of the "survival" effect and change of the plasmid replicative properties. A relationship between the replicon elements, the EcoRV genes region and "survival" effect is discussed. Based on the replicon found multicopy vector molecules have been constructed.

Base Sequence↗
PubMedDate not supplied

[Cloning and regulation of gene expression of EcoRV restriction- modification system].

A number of recombinant plasmids, containing EcoRV restriction-modification genes have been constructed. Individual genes of this system were introduced into plasmids of various incompatibility groups. Promoter regions of genes encoding methylase and restrictase have been cloned and studied. With the use of specialized vector pVE8 it was shown that the efficiency of the endonuclease gene promoter is comparable with early lambda phage promoters and produced about 70% of PL efficiency. The efficiency of the methylase gene promoter region was twice less than the efficiency of the restriction endonuclease gene promoter. Plasmid with restriction endonuclease gene promoter located downstream in relation to the additional regulatable phage lambda promoter PL has been obtained. It enabled us to construct strains 30-40 fold overproducing this enzyme under conditions of inactivation of the temperature sensitive phage repressor c1857. This construction directs the production of a high level (10%) of the total cellular soluble proteins) of the EcoRV restriction enzyme. The factors that influenced the level of enzyme synthesis under induction are discussed.

Base Sequence↗