Book of Abstracts: Albany 2005

category image Volume 22
No. 6
June 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
Ky Lowenhaupt2
Alexander Rich2,*
Yang-Gyun Kim3
Kyeong Kyu Kim1

1Dept. of Molecular Cell Biology
Samsung Biomedical Research Institute
Sungkyunkwan University School of Medicine
Suwon 440-746, Korea
2Department of Biology
Massachusetts Institute of Technology
Cambridge, Massachusetts 02139, USA
3Dept. of Biochemistry
College of Medicine
Chung-Ang University
Seoul 156-756, Korea

*Phone: 617-253-4715
Fax: 617-253-8699
Email: cbeckman@mit.edu