1k2l
From Proteopedia
STRUCTURAL CHARACTERIZATION OF BISINTERCALATION IN HIGHER-ORDER DNA AT A JUNCTION-LIKE QUADRUPLEX
Overview
We report the single-crystal X-ray structure for the complex of the bisacridine bis-(9-aminooctyl(2-(dimethylaminoethyl)acridine-4-carboxamide)) with the oligonucleotide d(CGTACG)(2) to a resolution of 2.4A. Solution studies with closed circular DNA show this compound to be a bisintercalating threading agent, but so far we have no crystallographic or NMR structural data conforming to the model of contiguous intercalation within the same duplex. Here, with the hexameric duplex d(CGTACG), the DNA is observed to undergo a terminal cytosine base exchange to yield an unusual guanine quadruplex intercalation site through which the bisacridine threads its octamethylene linker to fuse two DNA duplexes. The 4-carboxamide side-chains form anchoring hydrogen-bonding interactions with guanine O6 atoms on each side of the quadruplex. This higher-order DNA structure provides insight into an unexpected property of bisintercalating threading agents, and suggests the idea of targeting such compounds specifically at four-way DNA junctions.
About this Structure
Full crystallographic information is available from OCA.
Reference
Structural characterisation of bisintercalation in higher-order DNA at a junction-like quadruplex., Teixeira SC, Thorpe JH, Todd AK, Powell HR, Adams A, Wakelin LP, Denny WA, Cardin CJ, J Mol Biol. 2002 Oct 18;323(2):167-71. PMID:12381312 Page seeded by OCA on Fri May 2 22:13:29 2008
