Guanine-rich nucleic acids self-assemble into a polymorphic family of quadruple helical structures known as G-DNA. Its common structural motif is a coplanar tetrad of guanine bases that, when stacked, have the capacity to coordinate some cations. Sequences capable of adopting a G-DNA structure are found throughout the genomes and their biological functions are linked to genome stability, regulation of gene expression and cellular senescence. This work describes interactions of cationic polymers used as DNA transfection agents with a supramolecular G-DNA known as a G-wire. Polyethyleneimine (PEI), TAT peptide and PAMAM dendrimer show high affinity for G-wires self-assembled in the presence of Na+, K+ and NH4+ when measured by Isothermal Titration Calorimetry (ITC). Dynamic light scattering (DLS) revealed the emergence of polydisperse aggregates form at charge ratios greater than 1(+:-) ranging in diameter (100-1000 nm). The analyses of binding interactions indicate that G-DNA remains intact, supporting results from ITC and DLS.

Characterization of cationic DNA transfection agents binding to supramolecular G-DNA

245th National Meeting (2013)

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