Antiswitches

Antiswitches, trans-RNA molecules that regulate translation of mRNA based on ligands, were first developed by Smolke and Bayer (2005) in Saccharomyces cerevisiae. Two types of antiswitches were engineered: on-switches and off-switches. On-switches turn on gene expression in the presence of the ligand while off-switches turn off gene expression in the presence of ligand.

Design

Antiswitches are made of an aptamer and two stems: the aptamer stem and the antisense stem. (insert picture of antiswitch)

The aptamer is the sequence that binds the ligand and causes a conformational (shape) change of the antiswitch molecule. While Smolke and Bayer used the aptamer for the ligand theophylline, aptamers for many other molecules are now being generated using rational design. The large number of possible aptamers provides versatility in what will control gene expression.