T-box leader

Usually found in gram-positive bacteria, the T box leader sequence is an RNA element that controls gene expression through the regulation of translation by binding directly to a specific tRNA and sensing its aminoacylation state. This interaction controls expression of downstream aminoacyl-tRNA synthetase genes, amino acid biosynthesis, and uptake-related genes in a negative feedback loop. The uncharged tRNA acts as the effector for transcription antitermination of genes in the T-box leader family. The anticodon of a specific tRNA base pairs to a specifier sequence within the T-box motif, and the NCCA acceptor tail of the tRNA base pairs to a conserved bulge in the T-box antiterminator hairpin.