Fig 1. Sequences and secondary structures of DNA molecules captured in the complex structures.

DNA1, DNA2, and DNA3 are self-complementary and form duplex via the sequences highlighted with underlines. DNA2 also form dG:dG Hoogsteen pairs at both ends. The red 2′,3′-dideoxy T (ddT) and 2′,3′-dideoxy A (ddA) residues are incorporated into the strands during crystallization.