Cyclic di-GMP-Responsive Transcriptional Reporter Bioassays in Pseudomonas aeruginosa.

3',5'-cyclic diguanosine monophosphate (cyclic di-GMP) is a bacterial secondary messenger molecule that regulates many important cellular activities and behaviors, such as motility and biofilm formation. While mass spectrometry protocols for quantitative analyses of intracellular cyclic di-GMP concentrations have been developed, they are time intensive, expensive, low-throughput, and incapable of directly monitoring dynamic changes in vivo. In this protocol, we provide a Pseudomonas aeruginosa-specific detailed methodology to assay the intracellular levels of cyclic di-GMP using biological reporters.