Ligand-induced translation by the allosteric ribosome bearing an aptamer-fused rRNA.

An RNA aptamer obtained by in vitro evolution can be used as an artificial molecular switch to regulate RNA function by additing a specific ligand. To construct novel translational control system in the cell, we created an "allosteric ribosome" consisted of 16S ribosomal (r) RNA that bears theophylline apatmer. The activity of the allosteric ribosome was monitored by enzymatic activity of chloramphenicol acetyl transferase (CAT) whose SD sequence in mRNA was altered to be recognized by the allosteric ribosome. Addition of theophylline caused a significant increase of CAT activity in dose-dependent manner, and conferred resistance against chloramphenicol on the cell.