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

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.