title: High-resolution structure of an extended A-tract: [d(CGCAAATTTGCG)]2.
abstract: The crystal structure of [d(CGCAAATTTGCG)]2 has been determined to 1.5 A resolution, representing the first high-resolution structure of this DNA fragment. The ion interactions are novel. A spermine molecule replaces a Mg2+ observed in analogous structures. Unlike lower-resolution structures, the minor groove is narrow and the major groove lacks extra Watson-Crick hydrogen bonds. In addition, a monolayer of solvent sites, including a "spine of hydration", is visible in the minor groove. The crystal of [d(CGCAAATTTGCG)]2 was grown from a solution containing spermine, magnesium, and lithium. The conformation recapitulates that of "monovalent-minus" DNA.
authors.affiliation: School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA 30332-0400, USA.
authors.forename: Kristen Kruger
authors.initials: KK
authors.lastname: Woods
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Maehigashi
authors.forename: Shelley B
authors.initials: SB
authors.lastname: Howerton
authors.forename: Chad C
authors.initials: CC
authors.lastname: Sines
authors.forename: Sarah
authors.initials: S
authors.lastname: Tannenbaum
authors.forename: Loren Dean
authors.initials: LD
authors.lastname: Williams
mesh_terms: D000225:Adenine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D006860:Hydrogen Bonding; D008094:Lithium / Q000737:chemistry; D008274:Magnesium / Q000737:chemistry; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry*; D013941:Thymine / Q000737:chemistry
chemical_list: D009841:Oligonucleotides; D004247:DNA; D008094:Lithium; D008274:Magnesium; D000225:Adenine; D013941:Thymine