Metalloriboswitches: RNA-based inorganic ion sensors that regulate genes [Gene Regulation] (Journal of Biological Chemistry)

Divalent ions fulfill essential cellular roles and are required for virulence by certain bacteria. Free intracellular Mg2+ can approach 5 mm, but at this level Mn2+, Ni2+, or Co2+ can be growth-inhibitory, and magnesium fluoride is toxic. To maintain ion homeostasis, many bacteria have evolved ion sensors embedded in the 5´-leader sequences of mRNAs encoding ion uptake or efflux channels. Here, we review current insights into these `metalloriboswitches,` emphasizing ion-specific binding by structured RNA aptamers and associated conformational changes in downstream signal sequences. This riboswitch-effector interplay produces a layer of gene regulatory feedback that has elicited interest as an antibacterial target.