Cryo-EM-guided engineering of T-box-tRNA modules with enhanced selectivity and sensitivity in translational regulation.

Riboswitches are non-coding RNA elements that play vital roles in regulating gene expression. Their specific ligand-dependent structural reorganization facilitates their use as templates for design of engineered RNA switches for therapeutics, nanotechnology and synthetic biology. T-box riboswitches bind tRNAs to sense aminoacylation and control gene expression via transcription attenuation or translation inhibition.

Determinants of target prioritization and regulatory hierarchy for the bacterial small RNA SgrS.

Small RNA (sRNA) regulators promote efficient responses to stress, but the mechanisms for prioritizing target mRNA regulation remain poorly understood. This study examines mechanisms underlying hierarchical regulation by the sRNA SgrS, found in enteric bacteria and produced under conditions of metabolic stress. SgrS posttranscriptionally coordinates a nine-gene regulon to restore growth and homeostasis.

New tRNA contacts facilitate ligand binding in a T box riboswitch.

T box riboswitches are RNA regulatory elements widely used by organisms in the phyla Firmicutes and Actinobacteria to regulate expression of amino acid-related genes. Expression of T box family genes is down-regulated by transcription attenuation or inhibition of translation initiation in response to increased charging of the cognate tRNA. Three direct contacts with tRNA have been described; however, one of these contacts is absent in a subclass of T box RNAs and the roles of several structural domains conserved in most T box RNAs are unknown.

SHAPE analysis of the RNA thermometer from .

RNA thermometers regulate expression of some genes involved in virulence of pathogenic bacteria such as , , and They often function through temperature-dependent conformational changes that alter accessibility of the ribosome-binding site. The 5'-untranslated region (UTR) of the mRNA from contains a very short RNA thermometer. We have systematically characterized the structure and dynamics of this thermometer at single-nucleotide resolution using SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) assays.