A small unstructured nucleic acid disrupts a trinucleotide repeat hairpin.

Amalia Avila-Figueroa, Douglas Cattie, Sarah Delaney

Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912, United States.

Biochemical and biophysical research communications 2011 Oct 7

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A variety of neurodegenerative disorders are associated with the expansion of trinucleotide repeat (TNR) sequences. These repetitive sequences are prone to adopting non-canonical structures, such as intrastrand stem-loop hairpins. Indeed, the formation and persistence of these hairpins during DNA replication and/or repair have been proposed as factors that facilitate TNR expansion. Given this proposed contribution of TNR hairpins to the expansion mechanism, disruption of such structures via strand invasion offers a potential means to negate the disease-initiating expansion. In this work, we investigated the strand invading abilities of a (CTG)(3) unstructured nucleic acid on a (CAG)(10) TNR hairpin. Using fluorescence, optical, and electrophoretic methods, instantaneous disruption of the (CAG)(10) hairpin by (CTG)(3) was observed at low temperatures. Additionally, we have identified three distinct duplex-like species that form between (CAG)(10) and (CTG)(3); these include 1, 2, or 3 (CTG)(3) sequences hybridized to (CAG)(10). The results presented here showcase (CTG)(3) as an invader of a TNR hairpin and suggest that unstructured nucleic acids could serve as a scaffold to design agents to prevent TNR expansion. Copyright © 2011 Elsevier Inc. All rights reserved.

Citation

Amalia Avila-Figueroa, Douglas Cattie, Sarah Delaney. A small unstructured nucleic acid disrupts a trinucleotide repeat hairpin. Biochemical and biophysical research communications. 2011 Oct 7;413(4):532-6