Nucleic Acids Research, 1994, Vol. 22, No. 19 3977-3982
© 1994
RNA |
Comparison of antiparallel A-AT and T-AT triplets within an alternate strand DNA triple helix
Department of Physiology and Pharmacology, University of Southampton Bassett Crescent East, Southampton SO9 3TU, UK
*To whom correspondence should be addressed
Received May 11, 1994. Revised August 15, 1994. Accepted August 15, 1994.
We have examined the formation of alternate strand triple-helices at the target sequence A11(TC)6-(GA)6T11 using the oligonucleotides T11(AG)6 and T11(TG)6, by DNase I footprinting. These third strands were designed so as to form parallel T-AT triplets together with antiparallel G-GC and A-AT or T-AT triplets. We find that, although both oligonucleotides yield clear footprints at similar concentrations (0.3 µM) in the presence of manganese, only T11(TG)6 forms a stable complex in magnesium-containing buffers, albeit at a higher concentration (1030 µM). Examination of the interaction of (AG)6 and (TG)6 with half the target site confirmed that the complex containing A-AT triplets was only stable in the presence of manganese. In contrast no binding of (TG)6 was detected in the presence of either metal ion, suggesting that the reverse-Hoogsteen T-AT triplet is less stable that GGC. We suggest that, within the context of GGC triplets, the rank order of antiparallel triplet stability is A·AT(Mn2+) > T.AT(Mn2+) > T.AT (Mg2+) > A.AT (Mg2+). Third strands containing a single base substitution in the centre of either the parallel or antiparallel portion showed a (10-fold) weaker interaction in manganese-containing buffers, and no interaction in the presence of magnesium.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
A. Bacolla, M. J. Ulrich, J. E. Larson, T. J. Ley, and R. D. Wells An Intramolecular Triplex in the Human [IMAGE]-Globin 5`-Flanking Region Is Altered by Point Mutations Associated with Hereditary Persistence of Fetal Hemoglobin J. Biol. Chem., October 13, 1995; 270(41): 24556 - 24563. [Abstract] [Full Text] [PDF] |
||||
