Aa. Wood et al., SEQUENCE-DEPENDENT CROSSED HELIX PACKING IN THE CRYSTAL-STRUCTURE OF A B-DNA DECAMER YIELDS A DETAILED MODEL FOR THE HOLLIDAY JUNCTION, Journal of Molecular Biology, 269(5), 1997, pp. 827-841
The structure of the B-DNA decamer d(CGCAATTGCG)(2) has been determine
d by X-ray diffraction analysis to a resolution of 2.3 Angstrom and an
R-factor of 17.7%. The decamer crystallises in the monoclinic space g
roup C2 and packs with a crossed arrangement of helices and a unique c
rossing contact distinct from all other decamer structures. This is be
lieved to be a direct result of the sequence-dependent minor groove wi
dth of the duplex. Crossed helix structures of DNA are valuable starti
ng points for modelling studies of the Holliday junction. Two unique s
ites are observed at the cross-over junction where strand exchange may
occur. A Holliday junction model has been constructed for each case a
nd modelled using molecular mechanics and dynamics techniques. One of
these models was found to be fully consistent with the available physi
cal data. (C) 1997 Academic Press Limited.