Second messenger c-di-AMP regulates potassium ion transport in bacteria

Abstract:

Potassium ion (K⁺) is a ubiquitous monovalent cation necessary for all living cells. To maintain homeostatic intracellular K⁺ concentration, most prokaryotes possess several unique K⁺ uptake systems to transport K⁺. A newly found second messenger-cyclic diadenosine monophosphate (c-di-AMP), plays an important role in regulating K⁺ transport by binding to several K⁺ transport-related proteins, such as KdpD, KtrA and TrkA. When the intracellular c-di-AMP concentration is high, c-di-AMP can bind its receptor or effector proteins to inhibit transporter activity. In addition, riboswitch could also be targeted by c-di-AMP to control the transcription of downstream K⁺ transporter genes, including ktr, trk and kdp operon and kup gene. High intracellular c-di-AMP concentration depresses bacterial K⁺ uptake. Therefore, understanding the mechanism of K⁺ transport inhibition by c-di-AMP not only enriches the regulation mode of the K⁺ transport, but also sparkle new ideas for the control and applications of bacteria.