[pSTS4--a new shuttle vector for cyanobacterium Plectonema boryanum CALU 465].

Three vector constructions--pSTS2, pSTS3 and pSTS4 have been obtained on the basis of the standard vector for Escherichia coli pBR 322, cyanobacterial plasmid pSM1 and its separate fragments. The structure of pSTS4, carrying the full-size plasmid pSM1 (cloned by the restriction site Hpa II), replicated both in the cells of E. coli and in the cells-transconjugants of the trichomal cyanobacterium Plectonema boryanum. Under these conditions resistance of P. boryanum cells to ampicillin increases three orders, and to tetracyclin--50 times. Structural integrity of pSTS4 is stably supported in conjugates during seven successive passages (time of the experiment) and preserved the transforming capacity in respect of the cells of E. coli. It is supposed that pSTS4 is a shuttle-vector with two active origins of replication; one of them provides for the replication of pSTS4 in E. coli cells, another--in P. boryanum cells.