page_title: T-box leader
section_title: tRNA-mediated attenuation
hierarchical_section_title: T-box leader / tRNA-mediated attenuation
caption_attribution_description: English: When the uncharged tRNA is abundant, the tRNA binds, the T-Box Leader takes on its antiterminator form, and transcription is not terminated
context_page_description: 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.
context_section_description: Although the exact mechanism of T box leader is still unclear and currently being studied, it has recently been recognized as a member of an expanding group of RNAs that are phylogenetically conserved across many gram-positive bacteria. They are structurally complex and able to directly sense physiological signals which results in the control of downstream gene expression. This controlling of gene expression is accomplished by transcriptional attenuation—a general transcriptional regulation strategy that senses when an alteration in the rate of transcription is necessary and initiating alteration at a particular site (sometimes preceding one or more genes of an operon). The operons that encode aminoacyl-tRNA synthetases, regulated by tRNA-mediated transcriptional attenuation, contain a leader region that specifies a transcript segment that can fold and eventually form a complex set of structures. Two of the most crucial segments to attenuation function as both the terminator and the antiterminator in different regulatory situations.
caption: When the uncharged tRNA is abundant, the tRNA binds, the T-Box Leader takes on its antiterminator form, and transcription is not terminated
exif: {"Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image ExifOffset": "78", "EXIF ExifImageWidth": "720", "EXIF ExifImageLength": "540"}