[Transcriptional mapping and study of transcription regulation of the Pseudomonas aeruginosa phage-transposon D3112]. / Transkriptsionnoe kartirovanie i izuchenie reguliatsii transkriptsii faga-transpozona D3112 Pseudomonas aeruginosa.

Regulation of transcription was studied in a wild-type transposable phage (TP) D3112 of Pseudomonas aeruginosa and its mutants for different genes. For this purpose, [3H]RNA-DNA hybridization with denatured fragments from various regions of the D3112 genome bound to nitrocellulose filters was used. A transcriptional map of TP D3112 was constructed based on the data obtained. The map comprised six independent transcriptional units corresponding to the modular organization of the phage genome. Only the repressor gene cI was transcribed in the lysogenic state. After repressor thermoinactivation, the cI transcription ceased, and transcription occurred in the same order as the genes (modules) were located on the D3112 phage genetic map (from left to right): cip1 (a negative regulator) and early genes A and B (controlling the replication-transposition of the phage), nonessential genome region, genes C and the locus marked with the ts47 mutation (positive regulators of late gene transcription), the genes of the head morphogenesis, gene c91 (a positive regulator responsible for the lysogenic state), and the genes of the tail morphogenesis. Similarities between nonhomologous TPs D3112 of P. aeruginosa and Mu of Escherichia coli with respect to genetic organization and transcription regulation are discussed.

[Phenotypic effect of mutation ts47 in the Pseudomonas aeruginosa phage transposon D3112 on expression of late phage genes]. / Izuchenie fenotipicheskogo éffekta mutatsii ts47 faga-transpozona D3112 Pseudomonas eruginosa na vyrazhenie pozdnikh genov faga.

At nonpermissive temperature (42 degrees C) the ts47 mutation causes substantial abnormalities in the late phase of the phage intracellular development. In these conditions DNA of the D3112 phage is detected both in a free form and integrated into bacterial chromosome. The transcription kinetics in the ts47 mutant at 42 degrees C was indistinguishable from that typical to other early gene mutants (A, B, and C): specifically, the preservation of the first transcription peak along with low activity of late transcription were observed. Similarly to the C gene, the ts47 mutation-carrying locus is involved in regulating the transcription of the D3112 transposable phage late genes. It is suggested that the mechanism underlying the action of the ts47 mutation differs from that of the C gene product. One of the possible explanations is based on the fact that the product of the ts47 locus affects the activity of cellular RNA polymerase via providing more effective recognition of the phage promoters by the RNA polymerase modified with the phage protein C.

[Cloning and study of the expression of Pseudomonas aeruginosa cip1 gene by phage-transposon D3112 in a homologous host and in Escherichia coli]. / Klonirovanie i izuchenie ékspressii gena cip1 faga-transpozona D3112 Pseudomonas aeruginosa v gomologichnom khoziaine i v Escherichia coli.

Regulatory gene cipl of Pseudomonas aeruginosa transposable phage D3112 was cloned, and its expression was studied in P. aeruginosa and Escherichia coli. Overexpression of the cipl gene prevents transcription and replication of phage D3112 DNA and also lysogenization of bacteria P. aeruginosa PAO1 by phage D3112. The direction of cipl gene transcription within the vector was determined in the study of cipl gene expression, dependent on its orientation toward the gene lacZ promoter. The expression of the cloned cipl gene inhibited the specific TCS phenotype of E. coli (RP4 :: D3112) cells. The functional homology of the cipl gene of phage D3112 and the negative regulator ner of E. coli Mul phage was 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.

[Transcription of the genome of Pseudomonas aeruginosa phage-transposon D3112 in an homologous host]. / Izuchenie transkriptsii genoma faga-transpozona D3112 Pseudomonas aeruginosa v gomologichnom khoziaine.

In vivo transcription of Pseudomonas aeruginosa transposable phage D3112 was studied. The 3H-labelled RNA isolated from the lysogenic cells PAO1 (D3112cts) after heat induction was hybridized with D3112 DNA to estimate phage-specific RNA. Two main stages of D3112 transcription, including transcription of the early (first 6-8 min) and the late (after 8th min) genes, were revealed. The transcription rate of D3112 early genes achieves the maximum at 3-5 min, being reduced to the minimum at 6-8 min after heat induction. These data point to the existence of negative regulation of D3112 early genes' transcription. The influence of ts mutations in early A, B and C genes and in late ts25 gene on transcription of D3112 phage was studied. It is shown that the genes A and B have no effect on the late transcription, while gene C regulates transcription of the D3112 late genes.