Riboswitches

In the post-genomic era, many genes and regulatory elements remain uncharacterized, including riboswitches — RNA structures that control gene expression by directly binding metabolites. Here, a new type of metal-responsive riboswitch that senses sodium cations expands the bacterial Na⁺ metabolic repertoire.

Hiroshide Saito discusses two seminal papers that provided foundational evidence for the hypothesis that RNA with both genetic information and catalytic activity had an essential role in the origin of life.

Reliable quantification and tracing of RNA molecules remain challenging goals. A new fluorescent RNA tag, developed based on a natural adenine-sensing riboswitch and named Squash, offers superior imaging properties and accurate quantification in living cells.

Bacterial T-boxes are regulatory mRNA regions that control the transcription or translation of factors involved in amino acid supply. T-boxes act by directly binding to non-aminoacylated tRNA in response to amino acid starvation. Three studies now capture three-dimensional structures of tRNA–T-box complexes and reveal a set of RNA features that are required for the recognition of specific tRNAs and modulation of gene expression.

Riboswitches enable microbes to rapidly respond to changing levels of metabolites. A high-throughput platform reveals how RNA structural transitions kinetically compete during transcription in a new mechanism for riboswitch function.