1g3v
From Proteopedia
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CRYSTAL STRUCTURE OF NICKEL-D[CGTGTACACG]2
Overview
The aim of this study was to clarify whether Ni2+ ions could bind to, guanine bases in a standard B-DNA duplex and eventually induce a B-->Z, transition. We have determined by X-ray crystallography at 3.1 A, resolution the structure of the alternating deoxynucleotide d(CGTGTACACG), which contains both internal and terminal guanines. The duplex is in the B, form. It is shown that nickel ions bind selectively to the N7 atom of, guanine 10, which is in an extra-helical position, and guanine 2, which is, in the terminal position of the duplex. It does not bind to guanine 4, which lies within a standard B-DNA tract. This simple but unambiguous, result proves that nickel ions select between different guanines via, steric accessibility. Guanine-Ni2+-guanine bridges among symmetry-related, duplexes have also been found. These bridges may explain why Ni2+ ions may, act either as a precipitant or a renaturing agent for DNA under certain, conditions. The biochemical interaction of nickel with DNA can thus be, related to its capacity to specifically bind to B-DNA regions with exposed, guanines. Also, from the structural point of view, we have found a, terminal cytosine, which forms a C.G:C reverse-Hoogsteen triple structure, with a base pair of a neighbor duplex. This type of triplet is seldom, found and is here described for the first time for a DNA structure.
About this Structure
1G3V is a Protein complex structure of sequences from [1] with NI as ligand. Full crystallographic information is available from OCA.
Reference
Nickel-guanine interactions in DNA: crystal structure of nickel-d[CGTGTACACG]2., Abrescia NA, Huynh-Dinh T, Subirana JA, J Biol Inorg Chem. 2002 Jan;7(1-2):195-9. Epub 2001 Aug 25. PMID:11862555
Page seeded by OCA on Sun Nov 25 00:48:16 2007
