The CdaA Regulon in Streptoccus mutans

Nucleotide signaling pathways are found in all kingdoms of life and are utilized to coordinate a rapid response to changes in the environment. One more recently discovered signaling nucleotide is the secondary messenger cyclic diadenosine monophosphate (c-di-AMP), which is widely distributed among bacteria and is also found in several archaea. This cyclic nucleotide has been shown to involve in several important cellular processes, including maintenance of DNA integrity, cell wall metabolism, stress tolerance, transcription regulation and virulence. However, the mechanisms by which c-di-AMP modulates these physiological changes have remained largely unknown.In the present study, we identified and characterized a c-di-AMP synthase (CdaA) in S. mutans UA159. Furthermore, we investigated the role of CdaA in S. mutans cell physiology and global gene expression by utilizing cdaA gene in-frame deletion mutant. Our findings suggest that CdaA is an important global modulator of optimal growth and environmental adaption in this pathogen. Streptococcus mutans UA159 whole-genome arrays (8 x 15 K) were obtained from Agilent and included 1998 probes for S. mutans transcripts. For microarray analysis, S. mutans UA159 and S. mutans ΔcdaA cells were routinely grown at 37°C anaerobically (90% N2, 5% CO2, 5% H2) in brain heart infusion broth (BHI; Difco, Sparks, MD, USA) to an optical density at 600 nm (OD600) of 0.5. Four RNA samples isolated from four independent cultures of UA159 and cdaA mutant strains were hybridized to the arrays and analyzed.