A new base pair for DNA nanotechnology

A new DNA base pair that works with at least one enzyme that replicates DNA opens up new possibilities for nanotech. Biology-based pathways to productive nanosystems might be even more promising than they already are if the exquisite molecular recognition system of DNA could be expanded to include more than two types of base pairs. Other base pairs have been tested in the past, but failed to work with the necessary enzymes. Robert Adler at NewScientist.com news service reports that scientists at the Scripps Research Institute have now succeeded. An excerpt from “Artificial letters added to life’s alphabet“:

Two artificial DNA “letters” that are accurately and efficiently replicated by a natural enzyme have been created by US researchers. Adding the two artificial building blocks to the four that naturally comprise DNA could allow wildly different kinds of genetic engineering, they say.

Eventually, the researchers say, they may be able to add them into the genetic code of living organisms.

The diversity of life on earth evolved using genetic code made from arrangements of four genetic “bases”, sometimes described as letters. They are divided into two pairs, which bond together from opposite strands of a DNA molecule to form the rungs of its characteristic double-helix shape.

The unnatural but functional new base pair is the fruit of nearly a decade of research by chemical biologist Floyd Romesberg, at the Scripps Research Institute, La Jolla, California, US.

…Romesberg notes that DNA and RNA are now being used for hundreds of purposes: for example, to build complex shapes, build complex nanostructures, silence disease genes, or even perform calculations. A new, unnatural, base pair could multiply and diversify these applications.

It’s too early to say just how useful this will be to the development of atomically precise manufacturing (APM), but one can imagine near-term use in structures and devices built from DNA. The fact that at least one DNA polymerase recognizes the new base pair might be a real advantage in using in vitro evolution to produce DNA or RNA sequences that bind a specific target or have a desired catalytic activity. Longer term, expanding the genetic code to use additional, unnatural amino acids might enable evolving proteins with functions useful for APM.
—Jim