Electron Microscopy and Restriction Endonuclease Analysis of RSF2124-pLS11 Composite Plasmid ConstructedIn Vitro

Abstract
The structure of the composite plasmid (pAT2010) between Escherichia coli plasmid RSF2124 (ColEl-Apr) and Bacillus subtilis plasmid pLSll which was constructed in vitro by the “EcoRI-ligase method” was studied. The size distribution of pAT2010 and the heteroduplex molecules between pAT2010 and ColEl were confirmed by electron microscopy. The composite plasmid along with the component plasmid RSF2124 and pLS11 was digested by restriction endonucleases BamHl, SmaI, and SalI. RSF2124, pLSll, and pAT2010 were digested by BamNl into 1, 1, and 2 fragments, respectively. By Smal, the three plasmids were cut into 1, 0, 1 fragment, respectively, but by SalI, they were not digested.