[Role of phage LØ7 lysogeny in genetic variability of Escherichia coli].

Aim: Determine the possibility of Iysogenization of Escherichia coli single strain DNA (ssDNA) by 1ø7 bacteriophage from the Microviridae family and determine the role of phage lø7 lysogeny in genetic variability of these bacteria.

Materials And Methods: A method of E. coli K12 lysogenization by phage lø7 was developed.

[Precise excision of TN5 in Escherichia coli K12 mutants with alterations in common component of phosphotransferase system and in subunits of DNA-gyrase].

The effect of ptsH and gyrA mutations on precise excision (PE) of transposon Tn5 was studied in Escherichia coli K12. The conjugative plasmid with Tn5 integrated in the tet gene of Tn10 was used as a model in experiments. It was shown that mutational damage of HPr, a common component of the bacterial PEP-dependent phosphotransferase system (PTS), increased the frequency of PE.

[The influence of Bordetella pertussis bvgAS operon on formation and resolution of plasmid-chromosome cointegrates in Escherichia coli K12 mutants with damages in common components of the phosphoenolpyruvate:sugar phosphotransferase system].

The plasmids containing the genetically marked variants of Bordetela pertussi transposon TnBP were synthesized on the base of the plasmid with thermosensitive replication. The integration frequency of these plasmids into the E.coli K12 chromosome at non-permissive temperature (42 degrees C) was determined.

[Functional activity of transposase of Bordetella pertussis IS element in Escherichia coli cells].

An Escherichia coli strain producing transposase of a repeated sequence of Bordetella pertussis chromosome (RSBP) was constructed. A defective MGE-helper plasmid method, which allowed the determination of transposase functional activity was developed. It was shown that transposase synthesized in E.

[Identification of the open reading frame coding transposase of Bordetella pertussis RS-element].

A computer-aided analysis of the repeating sequence of Bordetella pertussis chromosome (RSBP3) revealed 3 open reading frames, one of whose (ORF1) can code a protein whose structure and properties are similar to those of transposasas, i.e. enzymes in charges for the traveling of migrating genetic elements of pro- and eukaryote.

[The multifunctional fructose-specific component of the phosphoenolpyruvate-dependent phosphotransferase system of Escherichia coli K12--fruA gene product].

Mutational damage of the ptsH gene leads to pleiotropic disturbance of sugar utilization in Escherichia coli K12. A fruS mutation suppresses the defect because of a constitutional expression of the fruB and fruA genes. FruB protein possessing a pseudo-HPr activity replaces the HPr.

[Isolation and properties of mutants devoid of pseudo-HPr activity of the fructose transfer system in Escherichia coli K12].

Mutants without pseudo-HPr activity intrinsic to the H domain of the FruB protein were obtained in Escherichia coli K12 through insertional mutagenesis by means of the MudIlac phage and TnPhoA transposon. For isolating these mutants, double mutants of enteric bacterium (ptsH fruR of ptsH fruS) were used as original strains. These double mutants were inactive with respect to the total HPr protein of the phosphoenolpyruvate-carbohydrate phosphotransferase system and could not provide constitutive synthesis of fructose-specific proteins of this system.

[Determination of the direction of transcription of Escherichia coli K-12 structural genes of the fructose regulon in vivo].

The direction of transcription of specific components of the fructose phosphotransferase system, the fruA, fruK, and fruB genes, was determined in vivo by plasmid F'ts1141ac. Transcription from each of these genes was shown to run in the same direction, counterclockwise with respect to the E. coli chromosomal map.

[Shigella flexneri mutation giving rise to the appearance of fosfomycin-resistant avirulent forms with disordered carbohydrate utilization].

The present work analyzes pt44 mutation in Sh. flexneri resulting in the appearance of the following phenotypical properties: resistance to phosphomycin, avirulence, pleiotropic disturbances in carbohydrate utilization. The data provided by the biochemical and genetic analysis have indicated that pts44 mutation occupies the region between purC and ptsI loci on the chromosome of Sh.

[Characteristics of attenuated immunogenic mutants of shigella flexneri selected from phosphomycin-resistant clones].

Sh. flexneri mutants No. 2a, resistant to phosphomycin (25 microgram/ml), differ in their fermentability in respect to glucose, mannitol, mannose and fructose.

[Effect of the dose of ptsI- and ptsH-genes on carbohydrate transport and regulation of lac-operon activity in Escherichia coli K-12].

Phage Mu-1 cts61 was used for transposition of pts1 and ptsH genes. The received F'-factors AUF2 and AUF3 carry short fragments of the bacterial chromosome. Merodiploid strains with double pts genes were selected in sexduction crosses with the appropriate recA recipients.

[Glucose transport system and regulation of gene expression in Escherichia coli].

The object of this work was to study the effect of mutations damaging protein components of the phosphoenolpyruvate-dependent phosphotransferase system (PTS) of E. coli on the regulation of the activity of catabolite-sensitive operons. Mutations ptsI and ptsH affecting the activity of the enzyme I and HPr protein made the synthesis of catabolite-sensitive enzymes resistant to the action of glucose, and at the same time decreased the rate of transport of this compound.

[Isolation and properties of merodiploid strains with F-factor including the pts-region of the Escherichia coli K-12 chromosome].

A technique of hybridization of haploid methanol-utilizing yeast Pichia pinus MH4 is worked out using UV- and N-nitrosoguanidine-induced auxotrophic mutants. Vegetative diploid cultures are isolated. Tetrad analysis and random spore analysis have revealed a meiotic nature of spores, recombination of genetic material in the process of sporulation and the chromosomal nature of some mutations.