Crystallographic studies of DNA helix structure

X-ray crystallography can reveal the three-dimensional structure of short fragments of DNA or RNA with unique precision. It provides information concerning both the global helical structure and the geometry of local features such as base-pair stacking patterns and backbone conformation. An analysis of the structures of a family of DNA decamers with related sequences, crystallizing in a number of different lattices, defines the ranges in which conformational parameters can vary in B-DNA helices and shows the correlations between them. Thus, these studies show the static structures and give insight into the mechanics of DNA helices by showing how a change of one local conformational parameter will influence others. Crystal structures are also used to assess the competing influences of nucleotide sequence and environment on the three-dimensional DNA structure. To extrapolate from DNA crystal structures to physical characteristics and function of these molecules in solution or embedded into a defined sequence context remains a major challenge.