GSE203590
Translation initiation of the MgtL leader peptide is essential for the expression of mgtA in Escherichia coli
Riboswitches are cis-acting regulating RNA elements mostly found in the 5'-UTR of bacterial mRNAs. The Salmonella enterica mgtA riboswitch controls mgtA expression upon the sensing of intracellular Mg2+ ions. A leader peptide (MgtL) is contained within the mgtA riboswitch and its translation has been previously shown to be affected by Mg2+ concentrations. The current regulatory model suggests that the efficiency of MgtL translation is inversely related to mgtA transcription. Herein we show that the orthologue mgtA riboswitch of Escherichia coli also contains a leader peptide but, unlike S. enterica, that its translation is proportionally related to mgtA expression. Our results also suggest that ribosome stalling at mgtL is crucial for mgtA expression. Together, our results indicate that in E. coli, the expression of the MgtL leader peptide and mgtA are positively coordinated according to the intracellular Mg2+ concentration, a unique mechanism among known riboswitches. Overall design: Comparative ribosome profiling analysis for escherichia coli k-12 under 20 µM MgSO4 and 50 µM MgSO4.