A riboswitch is a part of an mRNA molecule that can directly bind a small target molecule, and whose binding of the target affects the gene’s activity. Riboswitches were first identified in 2002 and can sense when a protein is needed and stop the creation of that protein when it is not needed.
Previously identified riboswitches respond to organic compounds such as nucleotides and sugars. In a first of its kind, however, researchers from the Washington University School of Medicine in St. Louis, have identified a riboswitch in Salmonella which sense and respond to a metal ion, in this case Magnesium.
When Groisman and his colleagues created a mutant strain lacking the phoQ gene, though, they were surprised to find that production of the instructions to make the MgtA protein could still somehow respond to magnesium, producing less of its protein at high magnesium levels.
Magnesium ions are essential to the stability of several different critical processes and structures in the cell. This research may be instrumental in elucidating the role of magnesium in the regulation of cellular processes. Read the full report on the Salmonella riboswitch from WUSTL.