[Stimulation of the lysogenization of Pseudomonas aeruginosa cells by phage transposon B39 induced by plasmid Rms163]. / Stimuliatsiia lizogenizatsii kletok Pseudomonas aeruginosa fagom--transpozonom B39, obuslovlennaia plazmidoi RMS163.

The influence of Rms163 plasmid on lysogenization of Pseudomonas aeruginosa cells by B39 phage was studied. Plasmid Rms163 was shown to increase the frequency of lysogenization of PAO1 cells 7-8 times. C-mutants of B39 phage were isolated. According to complementation test, c-mutants were distributed into two groups--cI and cII/III. The product of cI is essential for establishment and maintenance of lysogenic state, cII/cIII product being only necessary for establishment of lysogenization. The mutants with special characteristics were isolated: B39cx1 phage carries a mutation which seems to be located on a regulatory site essential for establishment of lysogenic state. The region of the B39 genome responsible for interaction with Rms163 plasmid was mapped. Possible mechanisms of Rms163 plasmid interference with transposable B39 phage are discussed.

[Expression of the genome of Mu-like phage D3112 specific for Pseudomonas aeruginosa in Escherichia coli and Pseudomonas putida cells]. / Ekspressiia genoma Mu-podobnogo faga D3112, spetsifichnogo dlia Pseudomonas aeruginosa, v kletkakh Escherichia coli i Pseudomonas putida.

The behavior of Escherichia coli cells carrying RP4 plasmid which contains the genome of a Mu-like D3112 phage specific for Pseudomonas aeruginosa was studied. Two different types of D3112 genome expression were revealed in E. coli. The first is BP4-dependent expression. In this case, expression of certain D3112 genes designated as "kil" only takes place when RP4 is present. As a result, cell division stops at 30 degrees C and cells form filaments. Cell division is not blocked at 42 degrees C. The second type of D3112 genome expression is RP4-independent. A small number of phage is produced independently of RP4 plasmid but this does not take place at 42 degrees C. No detectable quantity of the functionally active repressor of the phage was determined in E. coli (D3112). It is possible that the only cause for cell stability of E. coli (D3112) or E. coli (RP4::D3112) at 42 degrees C in the absence of the repressor is the fact of an extremely poor expression of D3112. In another heterologous system, P. putida both ways of phage development (lytic and lysogenic) are observed. This special state of D3112 genome in E. coli cells is proposed to be named "conditionally expressible prophage" or, in short, "conex-phage", to distinguish it from a classical lysogenic state when stability is determined by repressor activity. Specific blockade of cell division, due to D3112 expression, was also found in P. putida cells. It is evident that the kil function of D3112 is not specific to recognize the difference between division machinery of bacteria belonging to distinct species or genera. Protein synthesis is needed to stop cell division and during a short time period this process could be reversible. Isolation of E. coli (D3112) which lost RP4 plasmid may be regarded as an evidence for D3112 transposition in E. coli. Some possibilities for using the system to look for E. coli mutants with modified expression of foreign genes are considered.

[Interaction of Pseudomonas aeruginosa plasmids and mu-like phages: the suppression of the early stages of cell infection by phage D3112 in the presence of plasmid RPL11]. / Vzaiodeistvie nekotorykh plazmid i Mu-podobnykh fagov Pseudomonas aeruginosa: podavlenie rannikh étapov infektsii kletok fagom D3112 v prisutstvii plazmidy RPL11.

The growth of Mu-like, D3112, B39 and B3 bacteriophages of Pseudomonas aeruginosa on bacterial strains containing R plasmids was studied. Plasmids RPL11, Rms148 and Rms163 were shown to interfere with phage growth: 1) D3112 and B39 phages do not produce plaques on a lawn of PAO1 (Rms148) giving e.o.p. less than 10(-9); 2) RPL11 plasmid restricts phage D3112 growth (e.o.p. less than 10(-9), the growth of phage B3 being also restricted by this plasmid, though in considerably less extent; 3) phage B39 makes small and very turbid plaques on a lawn of PAO1 (Rms163) with e.o.p. 0,13, while c mutants form clear plaques on this lawn and grow with e.o.p. 1,0. The interference of plasmid RPL11 with phage D3112 growth was examined in detail. The plasmid did not affect phage D3112 adsorption and no restriction of phage DNA in R+ cells was found. However, phage genes controlling establishment of lysogeny and the lytic cycle were not expressed after infection. It was observed though, that if a cell contains both prophage D3112 and plasmid RPL11, no interference with repressor synthesis or phage development takes place after induction of prophage. The results obtained allow to conclude that: 1) RPL11 plasmid interference with phage D3112 growth is caused by the plasmid effect on one of the early stages in the development preceding phage DNA integration; 2) the process of primary integration after infection and that of reintegration of DNA after prophage induction are likely to differ.

[Integration of the genome of the Mu-like Pseudomonas aeruginosa bacteriophage D3112 into plasmid RP4 and its hybrid plasmid transfer into Pseudomonas putida and Escherichia coli C600 bacteria]. / Integratsiia genoma Mu-podobnogo bakteriofaga D3112 Pseudomonas aeruginosa v plazmidu RP4 i vvedeneie v sostave gibridnoi plazmidy v bakterii Pseudomonas putida i Escherichia coli C600.

The genome of a Mu-like bacteriophage D3112 specific for Pseudomonas aeruginosa was integrated in vivo into the RP4 plasmid. The fact of integration has been proved by two experiments: 1. The loss of RP4 plasmid is accompanied by loss of D3112 prophage; 2. Transfer of the plasmid by conjugation from Pseudomonas aeruginosa into bacteria of other species - P. putida PgG1 or Escherichia coli C600 leads to the occurrence of clones of these species which liberate phage capable of growing on the lawn of P. aeruginosa bacteria. The integrated state of D3112 inserted into RP4 is stable in P. aeruginosa, E. coli, P. putida. The transfer frequency of RP4 with integrated D3112 prophage into different bacteria which do not contain homoimmune prophage is essentially lower than that of the RP4 having no D3112 prophage. Specific manifestation of D3112 genome activity in E. coli cells is the sensitivity of cell growth to lower temperature (30 degrees C) of incubation.