Synthesis of high molecular weight polypeptides in Escherichia coli minicells directed by cloned Saccharomyces cerevisiae 2-micron DNA.

The minicell-producing Escherichia coli strain P 678-54 was transformed with a series of defined PTY chimeric plasmids consisting of yeast 2-micron DNA and E. coli plasmid pCR1. In minicells the integrated 2-micron DNA from yeast directed specifically the synthesis of six polypeptides with apparent molecular weights of 15,000, 17,500, 20,000, 22,000, 37,000, AND 48,000. The specificity of five other polypeptides, which cover a molecular weight range of 19,000 to 28,000, has not yet been established with certainty. Neither the orientation of the integrated DNA, nor the inversion which distinguishes the two structural forms of 2-micron DNA affected the polypeptides synthesized. However, integration at a given EcoRI site appeared to be correlated with the absence of one particular polypeptide band; this suggests that at least one of these sites is located in an expressed region of the DNA.