Construction of a shuttle vector consisting of the Escherichia coli plasmid pACYC177 inserted into the Streptomyces cattleya phage TG1.

The Escherichia coli plasmid, pACYC177, was inserted into the single PstI site of a deletion derivative of the Streptomyces cattleya phage, TG1. The hybrid molecule can be propagated as a phage in S. cattleya and as a plasmid in E. coli and is readily transferred between the two species by transfection and transformation. The kanamycin-resistance-encoding gene derived from pACYC177 is not expressed in lysogens of the hybrid phage. Analysis of deletion mutants of the hybrid phage indicated that at least 7.5 kb of phage DNA is dispensable. Some of the deletion mutants fail to lysogenize S. cattleya (Lyg- phenotype). The locations of these deletions are consistent with the location of the phage att site as previously established by Southern hybridization analysis. The thiostrepton-resistance-encoding gene derived from Streptomyces azureus was inserted into Lyg+ and Lyg- deletion derivatives and is expressed in S. cattleya.