DNA curvature at A tracts containing a non-polar thymine mimic
AUTOR(ES)
Maki, Angèle
FONTE
Oxford University Press
RESUMO
We report the first experimental probing of electrostatic interactions on the pyrimidine side of a bent A tract. Although the curvature of short A tracts (A4–A6) has long been studied, its physical origins remain under debate. Current hypotheses include the influence of major-groove hydrogen bonds between propeller-twisted base pairs, electrostatic effects of closely associated minor-groove cations, effects of minor-groove solvation, and stacking effects at the junctions adjacent to the A tract. We investigated this problem through the substitution of thymidines in A5 tracts by difluorotoluene deoxynucleoside (F), a non-polar molecule of the same size and shape which lacks hydrogen bonding and metal-ion complexing capabilities. Ligation experiments with phased A tracts demonstrated that F substitution has asymmetric effects on the bend angle. The strongest effects occurred at the second and third thymines where curvature was reduced from 19.8° to 5.3° and 9.6°, respectively. Moderate effects were observed with substitutions at positions 1 and 4, while substitution at position 5 had no effect on bend angle. The results support the hypothesis that highly localized electrostatic interactions are a principal cause of A-tract curvature. Furthermore, they are most consistent with the notion that local metal-ion complexation at O2 of thymine is a strong component of these interactions.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=149194Documentos Relacionados
- Anti-adhesion potential of non-polar compounds and extracts from Ficus natalensis
- Cardanols detected in non-polar propolis extracts from Scaptotrigona aff. postica (Hymenoptera, Apidae, Meliponini)
- Substitution of an essential adenine in the U1A–RNA complex with a non-polar isostere
- Chemical characterization by GC-MS and phytotoxic potential of non-polar and polar fractions of seeds of Dioteryx odorata (Aubl.) Willd. from Venezuelan regions
- GC-MS-Based Metabolomic Profiles Combined with Chemometric Tools and Cytotoxic Activities of Non-Polar Leaf Extracts of Spondias mombin L. and Spondias tuberosa Arr. Cam.