Research ArticleMicrobiology

Control of potassium homeostasis is an essential function of the second messenger cyclic di-AMP in Bacillus subtilis

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Sci. Signal.  18 Apr 2017:
Vol. 10, Issue 475, eaal3011
DOI: 10.1126/scisignal.aal3011

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c-di-AMP controls potassium homeostasis in bacteria

In Bacillus subtilis, the second messenger cyclic di-AMP (c-di-AMP) regulates the expression of many genes encoding potassium transporters by binding to a regulatory RNA structure called a riboswitch in a gene called ydaO, preventing transcription beyond the riboswitch. Gundlach et al. found that ydaO encoded a high-affinity potassium transporter and renamed it kimA (K+ importer A). Binding of c-di-AMP to the kimA riboswitch under high external concentrations of potassium and the resulting inhibition of kimA expression were essential to ensure bacterial viability under these conditions. KimA is a member of an evolutionarily conserved family of potassium transporters, suggesting that this regulatory mechanism for potassium homeostasis could be widespread among diverse bacterial taxa.