Characterization of unstable minisatellites in the human SCK1/SLI gene

In our previous work, the gap region that included the SCK1/SLI gene, which corresponded to GAP1 of human chromosome 19, was cloned using a yeast host system. Further analysis of the GAP1 sequence revealed that it contained several abnormalities, including large blocks of tandem repeats that could result in instability in E. coli. To characterize these repeated regions, we evaluated the DNA composition, phylogenic tree, and pairwise distances of its minisatellites. Furthermore, we examined the cloning efficiency of each minisatellite into the TA vector and the instability of the minisatellites during propagation in E. coli. From these studies, we observed that seven minisatellite regions yielded 0-30% cloning frequency, while others were cloned efficiently (90-100%). The cloning frequency in bacteria is affected by the GC content and the length of the repeats; however, the maintenance of the clones was unaffected by minisatellites. We suggest that minisatellite rearrangement can occur in the early stage of plasmid construction and duplication, thus their instability is dependent on both their length and DNA composition.