[Structural peculiarities of the SCP2 plasmid of Streptomyces coelicolor A3(2)]

Structural peculiarities of SCP2 plasmid isolated from different derivatives of Streptomyces coelicolor A3(2) were studied. By means of heteroduplexing 800 b.p. DNA insertion in SCP2 plasmid of S18-1 derivative was detected. The position of this insertion was localised on the SCP2 restriction map. A transposon-like structure with similar characteristics was detected and localised in different variants of SCP2 plasmid. This 600 bp DNA region is flanked by 20 bp inverted repeats and has the single EcoRI cleavage site. It is noted that the stretching of single-strand DNA circles of SCP2 plasmid was significantly less than that of single-strand DNA circles of pBR322 and PAS3; Tn9 plasmids. This may likely depend on the GC content of different plasmids.