Book of Abstracts: Albany 2011
June 14-18 2011
©Adenine Press (2010)
Structure and Reactivity of Triplet Repeat Sequences Associated with Neurodegenerative Disorders
Expansion of triplet repeat DNA is implicated in several neurodegenerative disorders, including Huntington’s Disease (HD). Expansion of the triplet repeat polymorphism is strongly dependent on repeat length, with longer repeats being more likely to expand across generations. While the mechanism of expansion for HD remains unknown, formation of non-B DNA structures by a repetitive (CAG)/(CTG) motif has been proposed to facilitate expansion. Persistence of the aforementioned non-B DNA structures during events such as DNA replication and/or repair could influence the likelihood of expansion to occur (1-5).
We studied the structural properties as well as the reactivity of a (CAG) 10 non-B hairpin construct and a series of complementary (CTG)n strands of variable length and sequence composition. A molecular beacon methodology was employed to monitor the behavior of the (CAG)10 hairpin by labeling with a 5'-fluorophore and a 3'-quencher functionalities (6). Modifications in the structure and base composition for the series of complementary hairpins have a profound effect on the stability of the (CAG)10 hairpin as seen by fluorescence and UV-Vis optical melting assays. Time-resolved electrophoretic assays also revealed that structural differences can alter the kinetics of hairpin-duplex conversion. These studies show that structure and base composition at distinct sites within these stem-loop DNA conformations influences molecular recognition between hairpins and modulates conversion to duplex.
This work was supported by National Institute of Environmental Health Sciences (R01ES019296). A.A.F. was supported by a National Science Foundation Graduate Research Fellowship.
Department of Chemistry