Active recombination of pKD1 derived vectors with resident pKD1 in Kluyveromyces lactis transformation

The host specificity of the 2 u-like circular plasmid pKD1 is such that this plasmid replicates stably in several species of Kluyveromyces yeasts, but not in Saccharomyces cerevisiae, pKD1-derived plasmids containing various parts of the pKD1 sequence were capable of transforming Kluyveromyces lactis with high efficiency. When such vectors were introduced into host strains that contained resident pKD1 plasmid, the input DNA frequently recombined with it to produce high proportions of additive recombinant molecules that replicate stably. Recombination events were shown to occur with vectors differing for the presence or absence of the putative origin of replication and of the inverted repeats. Structure, stability and copy number of the recombination products were analyzed for various types of vectors.