Book of Abstracts: Albany 2005
Crystal Structure of the B-DNA - Z-DNA Junction Reveals Two Extruded Bases
Although we have known the detailed structural features of both left-handed Z-DNA and right-handed B-DNA for many years, little was known about the junction between them. Here, we describe the structure of a B-Z junction as revealed by X-ray crystallography at 2.8 Å resolution. A fifteen base-pair segment of DNA is stabilized at one end in the Z conformation by Z-DNA binding proteins, while the other end remains B-DNA. Continuous stacking of bases between B-DNA and Z-DNA segments is found with extrusion of one base pair at the junction leaving a base exposed on each side. This raises the possibility that these extruded bases may be sites for DNA modification.
Sung Chul Ha1
1Dept. of Molecular Cell Biology