Cooperative recognition of a repetitive sequence through consecutive formation of triplex and duplex structures.

Cooperative recognition of a repetitive sequence was performed with a short single DNA strand consisting of duplex- and triplex-forming regions modified with a ligand (benzoquinoquinoxaline) to stabilize a triplex structure. The former region was complementary with one unit of a repetitive sequence and the latter had a sequence that can bind with a cognate duplex formed by another DNA molecule bound on an adjacent site. The DNA binding to one unit of the repetitive sequence is expected to facilitate the second binding to an adjacent unit through cooperative triplex formation. The cooperativity was confirmed by evaluation of thermal stabilities of the complexes with a series of model repetitive sequences.