Complexes between two GAA Repeats within DNA introduced into Cos-1 cells.

We have recently shown that GAA repeats severely impede replication elongation during the first replication cycle of transfected DNA wherein the chromatin is still at the formation stage.(1) Here we extend this study by showing that two GAA repeats located within the same plasmid in the direct orientation can form complexes upon transient transfection of mammalian Cos-1 cells. However, these complexes do not form in DNA that went through several replication rounds in mammalian cells. We suggest that formation of such complexes in mammalian genomes can contribute to genomic instability.