3TVB: A Highly Symmetric Dna G-4 QuadruplexDRUG COMPLEX

Citation:
Abstract
We have determined the X-ray structure of the complex between the DNA quadruplex d(5'-GGGG-3')(4) and daunomycin, as a potential model for studying drug-telomere interactions. The structure was solved at 1.08 A by direct methods in space group I4. The asymmetric unit comprises a linear arrangement of one d(GGGG) strand, four daunomycin molecules, a second d(GGGG) strand facing in the opposite direction to the first, and Na and Mg cations. The crystallographic 4-fold axis generates the biological unit, which is a 12-layered structure comprising two sets of four guanine layers, with four layers each of four daunomycins stacked between the 5' faces of the two quadruplexes. The daunomycin layers fall into two groups which are novel in their mode of self assembly. The only contacts between daunomycin molecules within any one of these layers are van der Waals interactions, however there is substantial pi-pi stacking between successive daunomycin layers and also with adjacent guanine layers. The structure differs significantly from all other parallel d(TGGGGT)(4) quadruplexes in that the 5' guanine adopts the unusual syn glycosyl linkage, refuting the widespread belief that such conformations should all be anti. In contrast to the related d(TGGGGT)/daunomycin complex, there are no ligand-quadruplex groove insertion interactions.
PDB ID: 3TVBDownload
MMDB ID: 97949
PDB Deposition Date: 2011/9/19
Updated in MMDB: 2012/07
Experimental Method:
x-ray diffraction
Resolution: 1.08  Å
Source Organism:
Biological Unit for 3TVB: octameric; determined by author
Molecular Components in 3TVB
Label Count Molecule
Nucleotide(1 molecule)
8
DNA (5'-d(gpgpgpg)-3')
Molecule annotation
Chemicals (12 molecules)
1
4
2
7
3
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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