Sandbox Reserved 402: Difference between revisions

Metabolite-binding riboswitches are triggered if a high concentration of the metabolite is present within the cell.  Under these conditions, the metabolite will interact with the aptamer domain, with high affinity and selectivity, which will then stabilize the metabolite bound fold in the nascent RNA, and in so doing prevents the formation of the metabolite-free fold.  This typically results in the stabilization or disruption of a regulatory hairpin, which prematurely terminates transcription or sequesters the ribosome-binding site, thereby regulating gene expression.  In the absence of the metabolite when the 5’-UTR is transcribed the riboswitch folds into the metabolite-free fold which does not interfere with the expression of the adjacent open reading frame.

In Bacillus subtilis, the 5'-UTR of xpt-pbuX mRNA binds guanine with high precision to down regulate the expression of genes by forming transcription terminator structures. <ref>PMID: 15610857 </ref>