1fn2

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spinqualitylabelsall models 1fn2, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

9-AMINO-(N-(2-DIMETHYLAMINO)BUTYL)ACRIDINE-4-CARBOXAMIDE BOUND TO D(CGTACG)2

Overview

The structures of the complexes formed between, 9-amino-[N:-(2-dimethyl-amino)butyl]acridine-4-carboxamide and, d(CG(5Br)UACG)(2) and d(CGTACG)(2) have been solved by X-ray, crystallography using MAD phasing methodology and refined to a resolution, of 1.6 A. The complexes crystallised in space group C222. An asymmetric, unit in the brominated complex comprises two strands of DNA, one, disordered drug molecule, two cobalt (II) ions and 19 water molecules (31, in the native complex). Asymmetric units in the native complex also, contain a sodium ion. The structures exhibit novel features not previously, observed in crystals of DNA/drug complexes. The DNA helices stack in, continuous columns with their central 4 bp adopting a B-like motif., However, despite being a palindromic sequence, the terminal GC base pairs, engage in quite different interactions. At one end of the duplex there is, a CpG dinucleotide overlap modified by ligand intercalation and terminal, cytosine exchange between symmetry-related duplexes. A novel intercalation, complex is formed involving four DNA duplexes, four ligand molecules and, two pairs of base tetrads. The other end of the DNA is frayed with the, terminal guanine lying in the minor groove of the next duplex in the, column. The structure is stabilised by guanine N7/cobalt (II), coordination. We discuss our findings with respect to the effects of, packing forces on DNA crystal structure, and the potential effects of, intercalating agents on biochemical processes involving DNA quadruplexes, and strand exchanges. NDB accession numbers: DD0032 (brominated) and, DD0033 (native).

About this Structure

1FN2 is a Protein complex structure of sequences from [1] with CO, NA and 8AD as ligands. Full crystallographic information is available from OCA.

Reference

A novel form of intercalation involving four DNA duplexes in an acridine-4-carboxamide complex of d(CGTACG)(2)., Adams A, Guss JM, Collyer CA, Denny WA, Wakelin LP, Nucleic Acids Res. 2000 Nov 1;28(21):4244-53. PMID:11058124

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