Rounding out cyclic dinucleotide signaling in Clostridioides difficile: A role and a mechanism for c-di-AMP.

The second messenger c-di-AMP contributes to various homeostatic and stress responses in bacteria. In this issue of Science Signaling , Oberkampf et al . have identified it as a mediator of osmotic stress and bile salt resistance in the opportunistic pathogen Clostridioides difficile , with additional roles in cell wall homeostasis and biofilm formation.