Title
A Parallel Stranded G-Quadruplex Composed of Threose Nucleic Acid (TNA)
Author
Jen-yu Liao, Irina Anosova, Saikat Bala, Wade D. Van Horn, John C. Chaput
Year
2016
Journal
Biopolymers
Abstract
G-rich sequences can adopt four-stranded helical structures, called G-quadruplexes, that self-assemble around monovalent cations like sodium (Na+) and potassium (K+). Whether similar structures can be formed from xeno-nucleic acid (XNA) polymers with a shorter backbone repeat unit is an unanswered question with significant implications on the fold space of functional XNA polymers. Here, we examine the potential for TNA (α-L-threofuranosyl nucleic acid) to adopt a four-stranded helical structure based on a planar G-quartet motif. Using native polyacrylamide gel electrophoresis (PAGE), circular dichroism (CD) and solution-state nuclear magnetic resonance (NMR) spectroscopy, we show that despite a backbone repeat unit that is one atom shorter than the backbone repeat unit found in DNA and RNA, TNA can self-assemble into stable G-quadruplex structures that are similar in thermal stability to equivalent DNA structures. However, unlike DNA, TNA does not appear to discriminate between Na+ and K+ ions, as G-quadruplex structures form equally well in the presence of either ion. Together, these findings demonstrate that despite a shorter backbone repeat unit, TNA is capable of self-assembling into stable G-quadruplex structures.
Instrument
J-710
Keywords
Circular dichroism, DNA structure, Thermal stability, Thermodynamics, Polymers, Biochemistry