The T box riboswitch: A novel regulatory RNA that utilizes tRNA as its ligand

The T box riboswitch is a cis-acting regulatory RNA that controls expression of amino acid-related genes in response to the aminoacylation state of a specific tRNA. Multiple genes in the same organism can utilize this mechanism, with each gene responding independently to its cognate tRNA. The uncharged tRNA interacts directly with the regulatory RNA element, and this interaction promotes readthrough of an intrinsic transcriptional termination site upstream of the regulated coding sequence. A second class of T box elements uses a similar tRNA-dependent response to regulate translation initiation. This review will describe the current state of our knowledge about this regulatory system. This article is part of a Special Issue entitled: Riboswitches.