Chemistry Reference
In-Depth Information
3
Metal Ion Coordination
in G - Quadruplexes
Janez Plavec
3.1 Introduction
DNA is able to adopt a variety of secondary structures other than the canonical B-
DNA which may potentially add considerable informational capacity to DNA.
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The initial concept of DNA being exclusively the holder of linearly arranged genetic
information is being revisited to add alternative DNA conformations as important
informational elements. Guanine nucleosides and nucleotides, as well as DNA (and
RNA) sequences that include tracts of contiguous guanine residues form four-
stranded structures known as G-quadruplexes (or tetraplexes or G4 structures).
Several reviews on G-quadruplexes have been published recently
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including the
monograph edited by Neidle and Balasubramanian.
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G - quadruplexes have been
proposed to play roles in DNA transactions such as replication, transcription and
recombination.
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These structures are adopted by G-rich nucleic acid sequences
which have been found to be abundant throughout the genomes of many organ-
isms.
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Potential G-quadruplex-forming regions are ample in telomers, oncogene
promoter sequences and other biologically relevant regions of the genome. The fact
that G-quadruplexes play roles in crucial biological processes makes them targets
for therapeutic intervention.
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G - quadruplex - forming oligonucleotide sequences,
which have the ability to selectively act as inhibitors of signal transduction or tran-
scription via binding to particular targets, are known as aptamers.
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In addition to
