Transformation of E. coli using homopolymer-linked plasmid chimeras

A number of parameters were explored to increase the transformation efficiency of E. coli with $\text{pBR}\text{322}\text{eukaryotic}$ DNA chimera, formed via d(A) · d(T) and d(G) · d(C) homopolymer tails. Of the E. coli strains analyzed, E. coli strain RR1 was the most efficient bacterial host. A clear optimum of nucleotide tail length existed for both types of homopolymer. The optimum hybridization temperature for chimera formation was found to be approx. 57°C. In the case of d(A) · d(T)-linked chimeras, 30 min was sufficient for optimum chimera formation. In contrast, d(C) · d(G)-linked chimeras required up to 2 h to give the best yields (as measured by transformation efficiency). Other minor factors affecting the transformation process are also explored and discussed.