title: DNA variability in five crystal structures of d(CGCAATTGCG).
abstract: The deoxyoligonucleotide d(CGCAATTGCG) has previously been crystallized in four different space groups. The crystals diffract to moderate resolution (2.3-2.9 A). Here, a fifth crystal form that diffracts to higher resolution (1.6 A) is presented which was obtained thanks to the use of Co2+ and cryogenic temperatures. The availability of five different crystal structures allows a thorough analysis of the conformational variability of this DNA sequence. It is concluded that the central hexamer sequence CAATTG has a practically constant conformation under all conditions, whilst the terminal base pairs at both ends vary considerably as a result of differing interactions in the crystals. The new crystal structure presented here is stabilized by guanine-Co2+-guanine interactions and the formation of C1+ -G8.C3 triplexes between neighbouring duplexes. As a result of the higher resolution of the crystal structure, a more regular structure was obtained and a clear definition of the spine of hydration was observed which was not visible in the four previous structures.
authors.affiliation: Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Avinguda Diagonal 647, E-08028 Barcelona, Spain.
authors.forename: Núria
authors.initials: N
authors.lastname: Valls
authors.forename: Glenford
authors.initials: G
authors.lastname: Wright
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Steiner
authors.forename: Garib N
authors.initials: GN
authors.lastname: Murshudov
authors.forename: Juan A
authors.initials: JA
authors.lastname: Subirana
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D003035:Cobalt / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D003854:Deoxyribonucleotides / Q000737:chemistry*; D006147:Guanine / Q000737:chemistry; D008958:Models, Molecular; D009690:Nucleic Acid Conformation
chemical_list: D003854:Deoxyribonucleotides; D003035:Cobalt; D006147:Guanine; D004247:DNA