4ocb

Publication Abstract from PubMed

A large number of Z-DNA hexamer duplex structures and a few oligomers of different lengths are available, but here the first crystal structure of the d(CGCGCGCGCGCG)2 dodecameric duplex is presented. Two synchrotron data sets were collected; one was used to solve the structure by the single-wavelength anomalous dispersion (SAD) approach based on the anomalous signal of P atoms, the other set, extending to an ultrahigh resolution of 0.75 A, served to refine the atomic model to an R factor of 12.2% and an R(free) of 13.4%. The structure consists of parallel duplexes arranged into practically infinitely long helices packed in a hexagonal fashion, analogous to all other known structures of Z-DNA oligomers. However, the dodecamer molecule shows a high level of flexibility, especially of the backbone phosphate groups, with six out of 11 phosphates modeled in double orientations corresponding to the two previously observed Z-DNA conformations: Z(I), with the phosphate groups inclined towards the inside of the helix, and Z(II), with the phosphate groups rotated towards the outside of the helix.

Phosphates in the Z-DNA dodecamer are flexible, but their P-SAD signal is sufficient for structure solution.,Luo Z, Dauter M, Dauter Z Acta Crystallogr D Biol Crystallogr. 2014 Jul;70(Pt 7):1790-800. doi:, 10.1107/S1399004714004684. Epub 2014 Jun 24. PMID:25004957^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.