A single G-to-C change causes human centromere TGGAA repeats to fold back into hairpins

摘要

Recently, we established that satellite III (TGGAA)n tandem repeats, which occur at the centromeres of human chromosomes, pair with themselves to form an un- usual "self-complementary" antiparallel duplex containing (GGA)_2 motifs in which two unpaired guanines from opposite strands intercalate between sheared GA base pairs. In sep- arate studies, we have also established that the GCA triplet does not form bimolecular (GCA)_2 motifs but instead pro- motes the formation of hairpins containing a GCA-turn motif in which the loop contains a single cytidine closed by a sheared GA pair.