Synthetic genetics – XNA

Philipp Holliger, of the UK Medical Research Council’s Laboratory of Molecular Biology, and his team of scientists have taken a new approach to the molecule of life and developed ‘synthetic DNA’. The ladder-like structure of the DNA double helix has bases that make up the rungs and sugar-phosphates as the sides. The synthetic version has been developed to have the same bases but different sugars, giving rise to its name xeno-nucleic acids (XNA), xeno being Greek for foreign.

Naturally occurring enzymes called polymerases carry out the copying of DNA molecules and scientists have engineered polymerases that can carry out this process to produce XNA from DNA in the laboratory, with 95 percent accuracy.

What’s got scientists excited is that this molecule shows the ability to evolve, in an experiment where a particular protein target was made that would specifically attach to XNA of certain sequences – the right order of rungs in the ladder – and the other XNA would wash away. As multiple copies of the attached XNA were made by the engineered polymerases, variations in the sequences of bases occurred to produce XNAs that could attach even more tightly to their protein target.

This discovery has shown that DNA is not unique in being able to evolve, which exobiologists (who study the idea of how life could occur on planets other than earth) believe has implications in their studies.

XNA has much potential in pharmaceutical research, as the body cannot break down its novel structure. The reason this is such a useful property is because current use of nucleic acids as antiviral and anticancer drugs has many pitfalls as enzymes in the bloodstream often rapidly break down the drugs, which would not be the case with XNA-based alternatives. The future of XNA and its uses is bright and could lead to some life-changing therapies.