title: Crystal structure of 15-mer DNA duplex containing unpaired bases.
abstract: Errors during DNA replication or repair can lead to the presence of unpaired or inserted bases in the double helix, as well as to mismatched base pairs. So far only structures of the latter type have been characterized by X-ray crystallography. We report here a 3-A crystal structure of DNA 15-mer d(CGCGAAATTTACGCG), which forms a duplex with two unpaired adenine residues looped outside the B-type helix. This arrangement is in disagreement with the nuclear magnetic resonance spectroscopy results for the same 15-mer in solution, indicating polymorphic nature of the structure adopted by this sequence.
authors.affiliation: Crystallography Laboratory, NCI-Frederick Cancer Research Facility, Maryland 21701.
authors.forename: M
authors.initials: M
authors.lastname: Miller
authors.forename: R W
authors.initials: RW
authors.lastname: Harrison
authors.forename: A
authors.initials: A
authors.lastname: Wlodawer
authors.forename: E
authors.initials: E
authors.lastname: Appella
authors.forename: J L
authors.initials: JL
authors.lastname: Sussman
mesh_terms: D000241:Adenosine; D001482:Base Composition; D003461:Crystallography; D004247:DNA; D004261:DNA Replication; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D012984:Software; D014961:X-Ray Diffraction
chemical_list: D004247:DNA; D000241:Adenosine