Angew. Chem. Int. Edn doi:10.1002/anie.200907082 (2010)

DNA structures can be created to manipulate other molecules, but controlling their activity has been a challenge. Xingguo Liang, Hiroyuki Asanuma and their colleagues at Nagoya University in Japan have now constructed one such single-molecule DNA 'nanomachine' that cleaves RNA and is controlled by light. This avoids the need to add small DNA or other 'fuel' molecules that would accumulate and interfere with the reactions.

The 'DNAzyme' is hairpin-shaped, with two parallel arms connected by a loop at one end, and both arms bind to the RNA. When illuminated with ultraviolet light, the hairpin opens, cleaving the RNA. It could be used to regulate gene expression, the authors suggest.