Abstract
Cyclic di-adenosine monophosphate (c-di-AMP) has emerged as an important bacterial signaling molecule that functions both as an intracellular second messenger in bacterial cells and an extracellular ligand involved in bacteria-host cross-talk. In this study, we identify and characterize proteins involved in controlling the c-di-AMP concentration in the oral commensal and opportunistic pathogen Streptococcus mitis (S. mitis). We identified three known types of c-di-AMP turnover proteins in the genome of S. mitis CCUG31611: a CdaA-type diadenylate cyclase as well as GdpP-, and DhhP-type phosphodiesterases. Biochemical analyses of purified proteins demonstrated that CdaA synthesizes c-di-AMP from ATP whereas both phosphodiesterases can utilize c-di-AMP as well as the intermediary metabolite of c-di-AMP hydrolysis 5′-phosphadenylyl-adenosine (pApA) as substrate to generate AMP, albeit at different catalytic efficiency. Using deletion mutants of each of the genes encoding c-di-AMP turnover proteins, we show by high resolution MS/MS that the intracellular concentration of c-di-AMP is increased in deletion mutants of the phosphodiesterases and non-detectable in the cdaA-mutant. We also detected pApA in mutants of the DhhP-type phosphodiesterase. Low and high levels of c-di-AMP were associated with longer and shorter chains of S. mitis, respectively indicating a role in regulation of cell division. The deletion mutant of the DhhP-type phosphodiesterase displayed slow growth and reduced rate of glucose metabolism.
Highlights
Cyclic-di-adenosine monophosphate (c-di-AMP) is a bacterial nucleotide messenger molecule that participates in both intracellular and extracellular signaling
We identified one CdaA-type diadenylate cyclase, one GdpP-type phosphodiesterase (Pde1) and one DhhP-type phosphodiesterase (Pde2) involved in regulating the c-di-AMP concentration of S. mitis CCUG 31611
This set of proteins involved in c-di-AMP turnover is preserved in all streptococci in which c-di-AMP signalling has been studied to date
Summary
Cyclic-di-adenosine monophosphate (c-di-AMP) is a bacterial nucleotide messenger molecule that participates in both intracellular and extracellular signaling. It functions as a second messenger, relaying intracellular and extracellular signals into bacterial cell responses. C-di-AMP can act as an extracellular ligand involved in bacteria-host cross-talk, modulating the host’s immune response. It is recognized by the sensor STING and the pattern recognition receptors DDX41, RECON and ERAdP of the host, leading to the induction of a type I interferon response or activation of NF-κB [8,9,10,11,12]. Mice models have highlighted the importance of the c-di-AMP signaling network in pathogenesis, where elevated c-di-AMP levels lead to attenuated virulence [3,14,15,16,17]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
