Coexistence of A- and B-form DNA in a single crystal lattice.
It is well known that DNA can exist in a variety of conformations which can be interconverted by relatively mild changes in conditions. The in vivo conformation of DNA is usually thought to be the B form, but there is recent evidence that other conformations may be important in DNA-protein recognition. Different fragments of DNA crystallized under virtually identical conditions can form A, B or Z helices. A fragment that adopted an A conformation in a crystal was found in the B conformation in solution, whereas NMR spectroscopy of A-DNA films revealed the presence of a substantial amount of disordered B-DNA. Until now, however, a DNA fragment of a given sequence has not been crystallized in more than one global conformation. We report here an X-ray diffraction study of crystals of the DNA octamer dGGBrUABrUACC. In addition to a 'framework' of A-DNA, which gives discrete X-ray reflections, there are partially disordered B-DNA helices, recognized by their diffuse scattering features.
Doucet
J
J
LURE Bat, Université Paris-XI, Orsay, France.
Benoit
J P
JP
Cruse
W B
WB
Prange
T
T
Kennard
O
O
D001973:Bromodeoxyuridine; D003460:Crystallization; D004247:DNA; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D014961:X-Ray Diffraction / Q000379:methods
D009838:Oligodeoxyribonucleotides; D004247:DNA; D001973:Bromodeoxyuridine