DNA variability in five crystal structures of d(CGCAATTGCG).
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.
Valls
Núria
N
Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Avinguda Diagonal 647, E-08028 Barcelona, Spain.
Wright
Glenford
G
Steiner
Roberto A
RA
Murshudov
Garib N
GN
Subirana
Juan A
JA
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
D003854:Deoxyribonucleotides; D003035:Cobalt; D006147:Guanine; D004247:DNA