engleski

A novel small linear element in the oxytetracycline producer Streptomyces rimosus

The strain S. rimosus R6-501 has a linear chromosome of 8 Mb and a linear plasmid pPZG101 of 387 kb. The ends of linear DNA molecules in Streptomyces usually possess covalently bound proteins on the 5' ends. A procedure was developed to isolate protein-bound DNA fragments in quantities sufficient for visualisation by agarose gel electrophoresis. When this was carried out with S. rimosus R6-501, in addition to the end fragments from the chromosome and pPZG101, a further unexpected fragment was detected and cloned. The additional fragment was due to the presence of a 4 kb linear element, which had not been detected previously, because it runs out of pulsed-field gels if standard programs designed for larger DNA fragments are used. An isolation method based on binding to glass beads allowed the preparative isolation of the element with its terminal protein intact. This is the first example of such isolation of intact linear plasmid from Streptomyces. This is important for analysing the replication of the ends and the development of novel cloning vectors.

Streptomyces rimosus; linear plasmid; novel genetic element

nije evidentirano