Details

Autor(en) / Beteiligte

• Praseuth, Danièle
• Perrouault, Loïc
• Le Doan, Trung
• Chassignol, Marcel
• Thuong, Nguyen
• Hélène, Claude

Titel

Sequence-Specific Binding and Photocrosslinking of α and β Oligodeoxynucleotides to the Major Groove of DNA Via Triple-Helix Formation

Ist Teil von

• Proceedings of the National Academy of Sciences - PNAS, 1988-03, Vol.85 (5), p.1349-1353

Ort / Verlag

Washington, DC: National Academy of Sciences of the United States of America

Erscheinungsjahr

1988

Quelle

MEDLINE

Beschreibungen/Notizen

• A photocrosslinking reagent (p-azidophenacyl) was covalently linked to an octathymidylate synthesized with either the natural (β ) anomer of thymidine or the synthetic (α ) anomer. The oligothymidylate was further substituted by an acridine derivative to stabilize the hybrid formed with a complementary octadeoxyadenylate sequence via intercalation. A single-stranded 27-mer containing a (dA)8 sequence and a 27-mer duplex containing a (dA· dT)8 sequence were used as targets. Upon UV irradiation, photocrosslinking of the octathymidylate to its target sequence was observed, generating bands that migrated more slowly in denaturing gels. In the 27-mer duplex, both strands were photocrosslinked to the octathymidylate. Upon alkaline treatment of the irradiated samples, cleavage of the 27-mers was observed at specific sites. These reactions were analyzed at different salt concentrations. The location of the cleavage sites allowed us to demonstrate the following. (i) Both α and β oligothymidylates can recognize a DNA double helix containing an oligo(dA)· oligo(dT) sequence; the oligothymidylate binds to the major groove of DNA in a parallel orientation with respect to the adenine-containing strand of the DNA double helix. (ii) α oligothymidylates form helices with a complementary single-stranded oligodeoxyadenylate; the two strands have a parallel orientation independently of whether or not an intercalating agent is attached to the oligothymidylate. (iii) At low salt concentration, β oligothymidylates form a double helix with an oligodeoxyadenylate in which, as expected, the two strands are antiparallel; at high salt concentration, a triple helix is formed in which the second oligothymidylate is oriented parallel to the adenine-containing strand. These results show that it is possible to recognize an oligopurine· oligopyrimidine sequence in a DNA double helix via local triple-helix formation and to target photochemical reactions to specific sequences in both double-stranded and single-stranded nucleic acids.