Transcriptional mapping and studying the control of transcription of the Pseudomonas aeruginosa transposable phage D3112

Regulation of transcription was studied in a wild-type transposable phage ( TP) D3112 of Pseudomonas aeruginosa and its mutants for different genes. Fo r this purpose, [H-3]RNA-DNA hybridization with denatured fragments from va rious regions of the D3112 genome bound to nitrocellulose filters was used. A transcriptional map of TP D3112 was constructed based on the data obtain ed. The map comprised six independent transcriptional units corresponding t o 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 le ft to right): cip1 (a negative regulator) and early genes A and B (controll ing 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 o f the tail morphogenesis. Similarities between nonhomologous TPs D3112 of P . aeruginosa and Mu of Escherichia coli with respect to genetic organizatio n and transcription regulation are discussed.