Nucleic Acids Research, Vol 24, Issue 17 3392-3398, Copyright © 1996 by Oxford University Press
E Brossalina, E Demchenko, Y Demchenko, V Vlassov and JJ Toulme
We used a DNA duplex formed between the 5' end of a 69mer (69T) and an
11mer (OL7) as a substrate for BamHI. The former oligonucleotide folds into
a hairpin structure, the stem of which contains a stretch of pyrimidines in
one strand and consequently a stretch of purines in the other strand. The
oligomer 69T was used as a target for complementary oligodeoxypyrimidines
made of 10 nt (OL1), 16 nt (OL5) or 26 nt (OL2) which can engage the same
10 pyrimidine-purine-pyrimidine triplets with the 69T hairpin stem.
Although the binding site of OL7 did not overlap that of OL1, OL2 or OL5,
the BamHI activity on 69T-OL7 complexes was drastically modified in the
presence of these triplex-forming oligomers: OL1 abolished the cleavage by
BamHI whereas OL5 and OL2 strongly increased it. Using footprinting assays
and point-mutated oligonucleotides we demonstrated that these variations
were due to different conformations of the 69T-OL7 complex induced by the
binding of oligomers OL1, OL2 or OL5. Therefore, oligonucleotides can act
as structural switchers, offering one additional mode for modulating gene
expression.
ARTICLES
Triplex-forming oligonucleotides trigger conformation changes of a target hairpin sequence
Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia.
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