Efforts to expand the genetic code

Abstract

In an effort to develop an unnatural base pair with which to expand the genetic code we have examined a wide variety of simple phenyl rings derivatized with methyl, fluoro, or nitrogen. The small aromatic surface of these base pairs should prevent inter-strand intercalation, which is thought to inhibit the polymerase-mediated synthesis of base pairs with larger aromatic surface area. Surprisingly, despite reduced aromatic surface area and hydrogen-bonding potential, some of these base pairs are stable and synthesized with reasonable efficiency. We have also been examining the use of activity-based selection systems to evolve DNA polymerases to more efficiently recognize the unnatural substrates, and our initial successes are described.