Poster abstracts
Poster number 59 submitted by Besik Kankia
Nucleic acid quadruplexes in biotechnological applications
Besik Kankia (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210), David Gvarjaladze (Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia), Adam Rabe (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210), Levan Lomidze (Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia), Nunu Metreveli (Institute of Biophysics, Ilia State University, Tbilisi 0162, Republic of Georgia), Karin Musier-Forsyth (Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210)
Abstract:
The biotechnological applications of DNA quadruplexes we are investigating are based on the unique properties of the GGGTGGGTGGGTGGG (G3T) oligomer: (i) it is capable of forming a quadruplex with significantly higher stability than the corresponding duplex; (ii) G3T acts as a monomeric unit for a higher degree of tetrahelical architecture; (iii) formation of the quadruplex represents an efficient molecular switch to turn on intrinsically fluorescent nucleotides.
Quadruplex priming amplification (QPA) employs the free energy of G3T as a driving force for endergonic DNA amplification. In addition, intrinsic fluorescence of G3T allows highly specific and sensitive monitoring of product DNA without any external quantification mechanisms. As a result, QPA represents an efficient alternative to PCR with plateau-free, isothermal, simplified and low-cost amplification of nucleic acid signals.
Quadruplex-and-Mg2+ connection (QMC) is based on the tetrahelical architecture of G3T and has two key components: (i) shape complementarity between QMC partners introduced by specific modifications of the quadruplexes and (ii) Mg2+ ions. The on-rate of QMC formation is between 105 - 106 M-1 s-1, while the off-rate is undetectable even at 80 °C. However, QMC dissociates rapidly upon removal of Mg2+ ions (i.e., by EDTA). QMC can create new opportunities in biomedical research by introducing a new class of capture molecules with advantages over the streptavidin-biotin system including reversibility, multiplexing, higher stability and specificity, longer shelf life and low cost.
DNA quadruplexes as structural and recognition elements in nanotechnology. The monomolecular tetrahelical architecture and QMC capabilities of quadruplexes have the potential to revolutionize DNA nanotechnology by introducing fast and error-free self-assembly of extraordinarily stable molecules. The advantages of the tetrahelical structure over DNA duplexes include: (i) monomolecularity of self-assembly, which eliminates errors characteristic of bi-molecular duplex formation; (ii) the ability to be folded/unfolded with little change in ionic strength; (iii) the folded structure is a tenth of the size of the original single strand, which could be used to induce movements in nanomachinery.
Keywords: quadruplexes, NA amplification, NA nanostructures