Creation of unnatural base pairs for genetic alphabet expansion toward synthetic xenobiology

Artificial extra base pairs (unnatural base pairs, UBPs) expand the genetic alphabet of DNA, thus broadening entire biological systems in the central dogma. UBPs function as third base pairs in replication, transcription, and/or translation, and have created a new research area, synthetic xenobiology, providing genetic engineering tools to generate novel DNAs, RNAs, and proteins with increased functionalities. Several UBPs have been developed and applied to PCR technology, DNA aptamer generation, and semi-synthetic organism creation. Among them, we developed a series of UBPs and demonstrated unique quantitative PCR and high-affinity DNA aptamer generation methods.