Properties of in vitro recombinant derivatives of pJV1, a multi-copy plasmid from Streptomyces phaeochromogenes

The 10.8 kb plasmid pJV1, isolated from Streptomyces phaeochromogenes, has a high copy number (about 150) and a broad host range among Streptomyces spp. Several pJV1 derivatives carrying the thiostrepton resistance gene (tsr) of S. azureus were made. One derivative, pWOR191, was shown to promote its own transfer and to mobilize chromosomal markers in S. lividans. Another derivative, pWOR109, was non-transmissible. Deletion in vitro of a segment of pWOR109 gave pWOR120 (5.6 kb), which has single BamHI and Bg/II sites shown to be capable of accepting 'foreign' DNA such as a previously cloned S. antibioticus DNA fragment encoding tyrosinase, giving vectors (pWOR125, pWOR126) with properties resembling the well-established multicopy vector pIJ702. Shuttle vectors capable of functioning in both S. lividans and Escherichia coli were also constructed. The region of pJV1 essential for replication and maintenance was localized to a 2.5 kb segment. Stable maintenance of pWOR109 and pWOR120 was observed in the presence of derivatives of pIJ101, the progenitor of pIJ702.