[Recombinational origin of natural transposable phages of related species belonging to group B3, active in Pseudomonas aeruginosa species]. / Rekominatsionnoe proiskhozhdenie prirodnykh fagov-transpozonov rodstvennykh vidov gruppy B3, aktivnykh na bakteriiakh vida Pseudomonas aeruginosa.

A heteroduplex analysis of four related transposable phages--B3, PM57, PM62, and Hw12--of the Pseudomonas aeruginosa B3 group was performed. Heteroduplex structures, restriction maps, and data on DNA-DNA hybridization obtained upon hybridization of phage DNA restriction fragments with labeled probes representing different regions of the phage genomes are in good agreement. The data obtained strongly confirmed the recombinational origin of the analyzed phages. Thus, all natural transposable phages of P. aeruginosa, including phages from both group B3 and species D3112, were shown to have a recombinational origin.

[Role of divergence in evolution of group B3 Pseudomonas aeruginosa transposable phage evolution]. / Vyiavlenie roli divergentsii v évoliutsii fagov-transpozonov gruppy B3 Pseudomonas aeruginosa.

A heteroduplex analysis was performed to identify and map divergent DNA sequences in the genomes of the P. aeruginosa transposable phages (TPs) of group B3 using different formamide concentrations (30, 50, and 70%). Six PTs were classified into three related species--B3, PM681, and PM57. The role of DNA divergence in the evolution of TPs within one species is insignificant: the genomes of phages pM105 and PM681 (species PM681) and phages Hw12 and pM57 (species pM57) were shown to contain either homologous (98%) or nonhomologous DNA (2%). Homologous, divergent, and nonhomologous DNA regions (modules) were identified in the genomes of the TP of different species. Homologous modules with a level of DNA homology higher than 86% constitute approximately 30% of the phage genome; they are located at the left (1-5 kb) and right (29-38 kb) ends of the phage genome. Divergent modules with a DNA homology level between 50 and 67% and nonhomologous modules represent 30 to 35% and 25 to 30% of the phage genome, respectively. These regions form a mosaic structure in a 5-29-kb region. Thus, the key role of DNA divergence in the evolution of the natural TPs of three related species of group B3 was shown. A single region containing a 5-11-kb divergent DNA sequence was detected in the pM62 phage genome (species pM57). As shown by our previous data, this region was integrated into phage pM62 via interspecific recombination with a phage of species B3.

[Plasmid transduction using the D3112DeltaH miniphage in Pseudomonas aeruginosa cells]. / Transduktsiia plazmid s pomoshch'iu minifaga D3112DeltaH v kletkakh Pseudomonas aeruginosa.

Plasmid DNA transduction with mini-D3112 delta H, deletion derivative of phage D3112, which lost the genes essential for phage growth but retained the sites required for transposition and packaging was studied. Unlike D3112, mini-D3112 delta H element can transduce plasmids and plasmid markers at frequencies of 10(-5)-10(-8) in rec+ cells of Pseudomonas aeruginosa. Plasmids R1162 and R388 of the size smaller than phage genome were transduced intact. Large plasmids, like RP4 and R151, were deleted under transduction. By this way, we isolated deletion derivatives of RP4. The smallest derivative pN2 contained a 4.5 kb fragment of RP4. Unlike the latter, pN2 plasmid had narrow host range and did not maintain in Escherichia coli cells.

[Genetic control of resistance of Escherichia coli K12 to phage C1]. / Geneticheskii kontrol' rezistentnosti Escherichia coli K12 k fagu C1.

The bacteriophage C1 isolated in production cycle lysis belongs to the most common group of bacteriophages wide spread in nature and having the long noncontractile motile tail. Bacterial cells sensitivity to bacteriophage C1 is determined by functioning of the three different loci mapped in different regions of Escherichia coli map at 89, 75 and 61 min. The possibility of existence of a complex receptor for bacteriophage C1 is discussed.

[Genetic control of morphogenesis of Pseudomonas aeruginosa transposable phage D3112]. / Geneticheskii kontrol' morfogeneza faga-transpozona D3112 Pseudomonas aeruginosa]

The influence of ts mutations in the early and late genes of transposable phage D3112 on phage morphogenesis was studied. The mutations in the early genes A, B and C were shown to suppress morphogenesis of D3112. Six genes (D, E, F, G, H and I), located from 14 to 29 kbp of the phage physical map, control morphogenesis of phage head. Five genes (J, K, L, M and N), clustered in the 29-36 kbp region of the map, control morphogenesis of tail. The similarity of genetic organization of the Escherichia coli transposable phage Mu and the Pseudomonas aeruginosa phage D3112 is discussed.

[Study of morphology and genome structure of Pseudomonas putida bacteriophages for their classification]. / Izuchenie morfologii chastits i struktury genomov bakteriofagov Pseudomonas putida s tsel'iu ikh klassifikatsii.

A group of 27 bacteriophages specific for Pseudomonas putida strains PpG1 and PpN has been isolated. The phages were characterized and compared with the previously described virulent (pf 16, af, tf and PMW) and temperate (PP56 and PP71) phages. The new phages belong to B1 and C1 morphotypes, according to Ackerman's classification. Phage DNAs were digested with several endonucleases; the molecular weights and homology of the DNAs were determined. All phages of P. putida isolated up to now were distributed into 10 species (groups), on the basis of particle morphology, genome size and the results of homology studies. Recombination processes are believed to participate in formation of phages belonging to certain species.

[2 types of molecular structure (composition) of a genome in one species of transposable bacteriophages of Pseudomonas aeruginosa]. / Dva tipa molekuliarnoi struktury (sostava) genoma v predelakh odnogo vida bakteropfagov-transpozonov Pseudomonas aeruginosa.

Comparison of heteroduplexes (HD) between DNAs of different transposable phages of Pseudomonas aeruginosa belonging to two previously described subgroups (D3112 and B3) revealed two types of structure (composition) of the bacteriophages, designated "type A" and "type B". The properties of genome structure of type A (phages of D3112 subgroup) are as follows: high level of conservation (up to 70% of genomes of different phages are represented as blocks of homologous DNA sequences); substitutions in genomes revealed as nonhomology regions in HD are, as a rule, small and located in certain sites; the distribution of the nonhomologous regions in HD of these phages is highly reproducible in independent experiments. Bacteriophages of subgroup B3 have genomes of type B: only a small part (approx. 30%) of genomes retain homology general for all of the phages; the nonhomologous regions are distributed in a large number of sites in HD; the sizes of nonhomologous regions are substantially larger than for the phages of subgroup D3112; distribution of the regions in HD is highly variable, which is characteristic of DNAs with partial homology. There is no difference between genomes of types A and B in G + C content (approx. 61-63%). Viable recombinants can be formed in crosses between phages of different genome types not only in regions with earlier revealed large DNA/DNA homology (right ends of genomes), but also in central portions of the genomes. Nevertheless, functional incompatibility of some regions of phage genomes of types A and B was demonstrated.

[Two loci in the genome of the Pseudomonas aeruginosa transposable phage B39 which affect the integration process. II. Mapping of the pdeX and pdeY loci by restriction and heteroduplex analysis]. / Dva lokusa v genome faga-transpozona B39 Pseudomonas aeruginosa, vliiaiushchie na protsess integratsii. Soobshchenie II. Opredelenie polozheniia lokusov pdeX i pdeY metodami restriktsionnogo i geterodupleksnogo analizov.

The coordinate function of two loci - pdeX and pdeY - in the genome of a transposable phage (TP) provides the phage function pde+ (good growth on bacteria with Rms163 plasmid). When these two loci in hybrid phages originate from different TP, some of the hybrid phages have Pde- phenotype. To localize pdeX and pdeY, the structure of hybrid TP genomes with Pde+ and Pde- phenotype obtained in crosses between B39ts+ and PH132 were studied using restriction and heteroduplex analysis. On the basis of data obtained, pdeX and pdeY were mapped in 2.85-6.4 and 6.4-16 kbp regions, respectively.

[Modular structure of the genes of phages-transposons of Pseudomonas aeruginosa]. / Modul'naia struktura genomov fagov-transpozonov Pseudomonas aeruginosa.

The basic criterion to confirm the recombinational origin of bacteriophages belonging to the same phage family is revealing several different combinations of differentiated segments in phage genomes which determine specific functions (modules). The results of phage-to-phage comparison of several regions in genomes of closely related transposable phages of Pseudomonas aeruginosa D3112, B39, PH2, PH51, PH93, PH132 have supported the modular hypothesis for this group of phages.

[Characteristics of phages-transposons of Pseudomonas aeruginosa belonging to 2 groups distinguished by DNA-DNA homology]. / Kharakteristika fagov-transpozonov Pseudomonas aeruginosa, otnosiashchikhsia k dvum gruppam, razlichimym po DNK-DNK-gomologii.

14 new transposable phages (TP) were isolated from approx. 200 clinical isolates of Pseudomonas aeruginosa. The frequent occurrence of TP of P. aeruginosa has been confirmed. There are at least two different groups of TP, namely, the group of D3112 and that of B3. The distinctive features of phages belonging to the groups are as follows: 1) low level of DNA-DNA homology (less than 10%), the whole region of homology in phage genomes of different groups being located on right genome end (29-38 kb); only one of phages of the B3 group shows an additional homology with D3112 DNA outside the above mentioned region; 2) a variable DNA is observed on the left end of the B3 group phage genomes and no such DNA is revealed on the left end of genomes of the D3112 group phages; 3) all phages of the B3 group have specific type of interaction with RPL11 plasmid, which distinguish them from phages of the D3112 group; 4) phages belonging to the two groups differ greatly in their growth in cells harbouring pMG7 plasmid which mediates production of PaeR7 endonuclease and in the number of DNA sites sensitive to SalGI, PstI, BglII endonucleases. Since some of the B3 group phage genomes possess BamH1 sites, resistance to this enzyme cannot be regarded as a general characteristics for all TP of P. aeruginosa, as it was earlier proposed. Some aspects of modular hypothesis of bacteriophage evolution concerning, in particular, the ways of module formation are discussed.

[Wide distribution of transposable phages in natural Pseudomonas aeruginosa populations]. / Shirokaia rasprostranennost' transpozonnykh fagov v prirodnykh populiatsiiakh Pseudomonas aeruginosa.

Five phages (PH2, PH51, PH59, PH93 and PH132) which have some characteristics common with D3112, the transposable phage of Pseudomonas aeruginosa, were isolated from clinical P. aeruginosa isolates. The phages were distributed into 4 different immunity groups. The basic criteria used for selection of transposable phages have been: 1) Morphology of a phage particle, host range, similar inactivation with antiserum; 2) Similar sizes of phage genomes; 3) The presence of a variable non-phage nucleotide sequences covalently linked to phage genome DNA, which could be identified using restriction endonucleases or by heteroduplex analyses. The DNAs of the new phages are resistant to treatment with BamH1 endonuclease, like the DNAs of phages D3112, B39 and B3 described earlier. The restriction maps of the phage genomes are constructed.

[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.

[Introduction of the hybrid plasmid RP4::D3112 into Pseudomonas putida cells requires the presence of specific mutation in the phage genome]. / Vvedenie v kletki Pseudomonas putida gibridnoi plazmidy RP4::D3112 trebuet nalichiia v genome faga spetsificheskoi mutatsii.

The wild type of D3112, a transposable phage of Pseudomonas aeruginosa can not be introduced as a portion of the hybrid plasmid RP4::D3112 into Pseudomonas putida cells. It is only possible when phage D3112 carries mutations designated lpc (lethal for P. putida and Escherichia coli). Analysis of heteroduplex molecules between DNAs of phages D3112w+ and D3112lpc demonstrated the absence of nonhomology regions, which suggests that lpc is a point mutation. The lpc2 mutation was located within the interval 20-29.9 kb of the phage genome.

Pseudomonas bacteriophage phi KZ contains an inner body in its capsid.

Electron microscopical examination of the new virulent bacteriophage phi KZ, specific for Pseudomonas aeruginosa, has revealed an unusual structure in its capsid. In the center of the phage head is a cylinder of low electron density ("inner body"), surrounded by fibrous material which is packed around the inner body in a spoollike manner. The inner body itself has a springlike appearance. These structures disappear after adsorption of phage particles to bacteria. Various morphological forms, which can be interpreted as intermediate steps in phi KZ DNA condensation, have been seen in ultrathin sections of phi KZ-infected cells.

[Electron microscope study of the intracellular development of the Pseudomonas aeruginosa bacteriophage phi KZ]. / Elektronno-mikroskopicheskoe izuchenie vnutrikletochnogo razvitiia bakteriofaga phi KZ Pseudomonas aeruginosa.

The study of the ultrathin sections of cells infected with virulent phage phi KZ has confirmed the presence of a specific cylindrical formation, an inner body, in the head of this phage and revealed the spiral structure of this inner body. The formation of DNA condensates whose structure resembles a spring wound around the core (the inner body) has been shown to occur in the cells in the process of the ultracellular development of phage phi KZ. This development leads to characteristic changes in the cellular structure, and in particular in the cell walls and the nucleoid.

[Genetic and phenogenetic study of the ts-mutant group of Pseudomonas aeruginosa PA01 phage phi KZ]. / Geneticheskoe i fenogeneticheskoe izuchenie gruppy ts-mutantov faga phi KZ Pseudomonas aeruginosa PA01.

A group of ts mutants of phi KZ phage specific for Pseudomonas aeruginosa was isolated and studied. A phi KZ phage particle has a unique feature: a specific structure as an internal body concerned with DNA packaging which is present in the phage capsid. Ts mutants were distributed into complementation groups. The time of the development block when grown at elevated temperatures was determined for mutants from several groups, the exact stage of the block having been defined for some late ts mutants. As was found for ts759, the stage of connection of heads containing DNA and the inner body with tails was blocked. The results obtained with ts759 allowed to prove the circular location of fibrous material (DNA?) around the inner body. The conditions for phage crosses were revealed. The genetic map of phi KZ is circular. It may be concluded, considering the linear phi KZ DNA structure in capsids, that circular permutations of phage DNA take place during phage maturation or DNA packaging.

[Isolation and analysis of phage-resistant Pseudomonas putida mutants using new bacteriophages]. / Vydelenie i analiz fagoustoichivykh mutantov Pseudomonas putida s pomoshch'iu novykh bakteriofagov.

Three new bacteriophages of Pseudomonas putida PpG1 have been isolated. Bacteriophages differ in many characteristics and are unrelated. Phage-resistant mutants of Pseudomonas putida PpG1 are selected using these phages and pf16 bacteriophage. No lysogenic variants were detected among these mutants. They have been distributed in seven groups according to their resistance to bacteriophages. The resistance to PMW phage was caused by at least two different mutations. Some of the phage-resistant mutants seem to cause the killing effect on Pseudomonas putida PpG1 cells.