Conclusion

In this study, coordination-driven base pair switching of modified uracil bases was proposed and applied to dynamic control of DNA structures. DNA strand displacement reactions essential for DNA structural conversion were successfully controlled in a GdIII-responsive manner by introducing 5-hydroxyuracil (UOH) bases at the termini of DNA strands. To resolve the sequence limitation of the UOH bases, an N,N-dicarboxymethyl-5-aminouracil (dcaU) base with an iminodiacetate ligand was developed and the GdIII-dependent base pair switching was achieved with a single incorporation of dcaU. Finally, it was demonstrated that UOH-modified DNA tweezers were reversibly opened and closed upon addition and removal of GdIII ions, respectively, under isothermal conditions. The introduction of modified uracil bases instead of natural T bases has little effect on the thermal stability and structures of DNA assemblies. Therefore, metal-responsive base pair switching is expected to be widely applicable to the dynamic control of DNA supramolecules. This chapter summarizes the achievements of this study and overviews future perspectives of the “base pair switching” technology.