Alternating d(G-A) sequences form a parallel-stranded DNA homoduplex.
AUTOR(ES)
Rippe, K
RESUMO
The oligonucleotides d[(G-A)7G] and d[(G-A)12G] self-associate under physiological conditions (10 mM MgCl2, neutral pH) into a stable double-helical structure (psRR-DNA) in which the two polypurine strands are in a parallel orientation in contrast to the antiparallel disposition of conventional B-DNA. We have characterized psRR-DNA by gel electrophoresis, UV absorption, vacuum UV circular dichroism, monomer-excimer fluorescence of oligonucleotides end-labelled with pyrene, and chemical probing with diethyl pyrocarbonate and dimethyl sulfate. The duplex is stable at pH 4-9, suggesting that the structure is compatible with, but does not require, protonation of the A residues. The data support a model derived from force-field analysis in which the parallel-stranded d(G-A)n helix is right-handed and constituted of alternating, symmetrical Gsyn.Gsyn and Aanti.Aanti base pairs with N1H...O6 and N6H...N7 hydrogen bonds, respectively. This dinucleotide structure may be the source of a negative peak observed at 190 nm in the vacuum UV CD spectrum, a feature previously reported only for left-handed Z-DNA. The related sequence d[(GAAGGA)4G] also forms a parallel-stranded duplex but one that is less stable and probably involves a slightly different secondary structure. We discuss the potential intervention of psRR-DNA in recombination, gene expression and the stabilization of genomic structure.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=556838Documentos Relacionados
- Formation of a parallel-stranded DNA homoduplex by d(GGA) repeat oligonucleotides.
- NMR structure of a parallel-stranded DNA duplex at atomic resolution
- Hairpin-dimer equilibrium of a parallel-stranded DNA hairpin: formation of a four-stranded complex.
- An interlocked dimeric parallel-stranded DNA quadruplex: A potent inhibitor of HIV-1 integrase
- Parallel-stranded DNA under topological stress: rearrangement of (dA)15.(dT)15 to a d(A.A.T)n triplex.