In Vivo Detection of Cyclic-di-AMP in Staphylococcus aureus .

Cyclic-di-AMP (CDA) is a signaling molecule that controls various cellular functions including antibiotic tolerance and osmoregulation in Staphylococcus aureus ( S. aureus ). In this study, we developed a novel biosensor ( bsuO P6-4) for in vivo detection of CDA in S. aureus . The fluorescent biosensor is based on a natural CDA riboswitch from Bacillus subtilis connected at its P6 stem to the dye-binding aptamer Spinach. Our study showed that bsuO P6-4 could detect a wide concentration range of CDA in both laboratory and clinical strains, making it suitable for use in both basic and clinical research applications.