THE PHENOTYPE OF RPI MUTANT OF PSEUDOMONA S-AERUGINOSA PHAGE-TRANSPOSON D3112 EXPRESSED IN A HETEROLOGOUS ESCHERICHIA-COLI HOST

A clone of Escherichia coli II-16 with unique properties was isolated upon incorporation of hybrid plasmid RP4:: D3112 with an integrated ge nome of phage-transposon D3112 Pseudomonas aeruginosa into E. coli C60 0 cells. The cells of this clone produce viable phage and are not sens itive to growth under low temperatures, which is characteristic of the majority of E. coli (RP4 :: D3112) clones with the genome of wild typ e phage. The clone E. coli II-16 contains phage genome both in an inte grated state within the chromosome and in plasmid RP4. The properties of phage D3112 in the clone II-16 demonstrated that the phage carried a mutation. The mutation was designated RP4-phage interaction (rpi). T he phenotypic effect of this mutation is expressed as phage inability to replicate in response to the presence of plasmid RP4 at 30 C (Tcs p henotype). The mutant rpi differs in its characters from the previousl y described mutants in the early regulator gene cip, the analog of the ner gene of E. coli phage Mu1, and from the known mutations in the A gene. Plasmid RP4 :: D3112 rpi exerts an inhibitory effect on the burs t size of RP4 :: D3112 in E. coli.