An earring for the double helix: Assembly of topological links comprising duplex DNA and a circular oligodeoxynucleotide

Novel DNA nanostructures, locked pseudorotaxane and locked catenane were as sembled through topological linkage of a double-stranded target to a circul ar oligodeoxyribonucleotide (cODN)(+). The formation of these supramolecula r complexes occurs with remarkable sequence specificity and is accomplished via local opening of duplex DNA by a pair of homopyrimidine bis-PNAs. The obtained cODN label, resembling an earring, forms a true topological link w ith the linear or closed circular (cc) target DNA and occupies a fixed posi tion along the double helix. The PNA directed assembly described here intro duces PNA oligomers into the repertoire of DNA nanotechnological tools.