Riboregulators

After observing the many and varied naturally occuring post-transcriptional, regulatory RNA systems, Isaacs et al. designed and engineered a modular synthetic system where RNA turns on and off gene expression by controlling translation. The modularity of their system allows any gene to be regulated instead of only a specific gene to which the riboregulator is targeted.

The design itself has two components: a short cis-repressed RNA sequence (crRNA) that is inserted upstream of the gene and a transactivating RNA sequence (taRNA) that targets the crRNA. The crRNA sequence contains two fundamental components: the complement of the ribosomal binding site (RBS) and a pyrimidine-uracil-nucleotide-purine (YUNR) sequence. When not interacting with the taRNA, the complement of the RBS binds to the RBS, causing the crRNA to loop and block the ribosome's access to the RBS. The YUNR sequence has a complement on the taRNA. When the taRNA finds a crRNA, the interaction with the YUNR sequence begins pulling the crRNA off the RBS.