DNA strand exchange reaction activated by cationic comb-type copolymers having ureido groups.

Abstract

Strand exchange reactions (SERs) of nucleic acids are essential for genetic recombination and often require nucleic acid chaperone activity. A variety of proteins induce strand exchange reactions in vivo. We have reported that cationic comb-type copolymers composed of a polycation backbone and hydrophilic graft chains greatly accelerate the SER in vitro and exhibit nucleic acid chaperone like activity. To elucidate structure/function relationships involved in the SER accelerating activity of the copolymer, we modified the copolymer with ureido groups. The melting temperature of dsDNA in the presence of the copolymers with ureido groups decreased with increasing ureido content, suggesting that the ureido groups have a destabilizing effect on the DNA duplex. Copolymers modified with ureido groups (about 50 mol%) accelerated a SER more strongly than unmodified copolymers. Given our previous observation that modification of the copolymer with guanidino groups resulted in enhanced chaperone-like activity, we propose that incorporation of chaotropic functional groups into the copolymer structure results in an increase in nucleic acid chaperone-like activity.