Characterization of 2-mum DNA of Saccharomyces cerevisiae by restriction fragment analysis and integration in an Escherichia coli plasmid.

Abstract

Electrophoretic analysis of EcoRI and HindIII restriction fragments of 2-.mu.m supercoiled DNA of S. cerevisiae indicated that this class of DNA is heterogeneous and probably consists of 2 types of molecules. Integration of the 2-.mu.m yeast DNA in E. coli plasmid pCRI directly showed the existence of 2 types of molecules, as each of these could be individually inserted into separate bacterial plasmids. The difference between the 2 types of 2-.mu.m circles is due to an inversion of about 1.6 .times. 106 daltons. The inversion is flanked by a reversed duplicated sequence of 0.45 .times. 106 daltons. Possible implications of this structure are discussed.