Nucleic Acids Research, Vol 27, Issue 3 859-865, Copyright © 1999 by Oxford University Press
KH Nam, S Abhiraman and RM Wartell
The ability of single-stranded DNA oligomers to form adjacent triplex and
duplex domains with two DNA structural motifs was examined. Helix- coil
transition curves and a gel mobility shift assay were used to characterize
the interaction of single-stranded oligomers 12-20 nt in length with a DNA
hairpin and with a DNA duplex that has a dangling end. The 12 nt on the
5'-ends of the oligomers could form a triplex structure with the 12 bp stem
of the hairpin or the duplex portion of the DNA with a dangling end. The
3'-ends of the 17-20 nt strands could form Watson-Crick pairs to the five
base loop of the hairpin or the dangling end of the duplex. Complexes of
the hairpin DNA with the single-stranded oligomers showed two step
transitions consistent with unwinding of the triplex strand followed by
hairpin denaturation. Melting curve and gel competition results indicated
that the complex of the hairpin and the 12 nt oligomer was more stable than
the complexes involving the extended single strands. In contrast, results
indicated that the extended single-stranded oligomers formed Watson-Crick
base pairs with the dangling end of the duplex DNA and enhanced the
stability of the adjacent triplex region.
ARTICLES
The formation of adjacent triplex-duplex domainsin DNA
School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA.
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