Recombination-like structure of d(CCGCGG).
We have solved the single crystal X-ray structure of the synthetic DNA hexamer d(CCGCGG). The central alternating tetramer forms a Z-DNA duplex. The initial cytosine of each strand of the duplex swings out and forms a Watson-Crick base-pair with the terminal guanine of a symmetry-related molecule. Thus, two symmetry-related DNA molecules form a twin with intermolecular base-pairs at both ends. Such a twin is additionally stabilized by a sodium ion located on a dyad axis between two DNA duplexes. The total structure has recombination-like features. It also provides a model for B/Z junctions. The crystal used in this study belongs to space group C222(1) with a = 34.33 A, b = 44.04 A and c = 38.27 A. The structure was solved by molecular replacement using partial models, and refined by molecular dynamics simulated annealing and positional treatment. The refinement has been concluded with an R-factor of 18.5% for 2377 reflections with F > or = 2 sigma (F) in the resolution region 8.0 to 1.92 A. The asymmetric unit contains two strands of d(CCGCGG) and 38 water molecules.
Malinina
L
L
Departament d'Enginyeria Química, Universitat Politècnica de Catalunya, Barcelona, Spain.
Urpí
L
L
Salas
X
X
Huynh-Dinh
T
T
Subirana
J A
JA
D003460:Crystallization; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry; D015226:Dinucleoside Phosphates / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000138:chemical synthesis / Q000737:chemistry*; D011995:Recombination, Genetic
D015226:Dinucleoside Phosphates; D009838:Oligodeoxyribonucleotides; C015101:cytidylyl-(3'-5')-cytidine; C018309:guanylyl-(3'-5')-guanosine; D004247:DNA