Molecular structure of r(GCG)d(TATACGC): a DNA–RNA hybrid helix joined to double helical DNA

Abstract
The molecule r(GCG)d(TATACGC) is self-complementary and forms two DNA–RNA hybrid segments surrounding a central region of double helical DNA its molecular structure has been solved by X-ray analysis. All three parts of the molecule adopt a conformation which is close to that seen in the 11-fold RNA double helix. The conformation of the ribonucleotides is partly determined by water molecules bridging between the ribose O2′ hydroxyl group and cytosine O2. The hybrid–DNA duplex junction contains no structural discontinuities. However, the central DNA TATA sequence has some structural irregularities.