Quantification of high-specificity cyclic diguanylate signaling

• Published in: Proceedings of the National Academy of Sciences - PNAS 2012-07, Vol.109 (31), p.12746-12751
• Main Authors: Massie, Jonathan P, Reynolds, Evan L, Koestler, Benjamin J, Cong, Jian-Ping, Agostoni, Marco, Waters, Christopher M
• Format: Article
• Language: English
• Subjects: Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; biofilm; Biofilms; Biofilms - growth & development; Biological Sciences; Correlation analysis; Correlations; Cyclic GMP - analogs & derivatives; Cyclic GMP - genetics; Cyclic GMP - metabolism; Cytometry; Enzymes; Escherichia coli - genetics; Escherichia coli - metabolism; Escherichia coli Proteins - genetics; Escherichia coli Proteins - metabolism; Gene expression; Gene expression regulation; Genes; Inductive reasoning; lifestyle; Molecules; Phosphorus-Oxygen Lyases - genetics; Phosphorus-Oxygen Lyases - metabolism; Quantification; Second Messenger Systems - physiology; signal transduction; Vibrio cholerae; Vibrio cholerae - physiology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1115663109

Cyclic di-GMP (c-di-GMP) is a second messenger molecule that regulates the transition between sessile and motile lifestyles in bacteria. Bacteria often encode multiple diguanylate cyclase (DGC) and phosphodiesterase (PDE) enzymes that produce and degrade c-di-GMP, respectively. Because of multiple inputs into the c-di-GMP–signaling network, it is unclear whether this system functions via high or low specificity. High-specificity signaling is characterized by individual DGCs or PDEs that are specifically associated with downstream c-di-GMP–mediated responses. In contrast, low-specificity signaling is characterized by DGCs or PDEs that modulate a general signal pool, which, in turn, controls a global c-di-GMP–mediated response. To determine whether c-di-GMP functions via high or low specificity in Vibrio cholerae , we correlated the in vivo c-di-GMP concentration generated by seven DGCs, each expressed at eight different levels, to the c-di-GMP–mediated induction of biofilm formation and transcription. There was no correlation between total intracellular c-di-GMP levels and biofilm formation or gene expression when considering all states. However, individual DGCs showed a significant correlation between c-di-GMP production and c-di-GMP–mediated responses. Moreover, the rate of phenotypic change versus c-di-GMP concentration was significantly different between DGCs, suggesting that bacteria can optimize phenotypic output to c-di-GMP levels via expression or activation of specific DGCs. Our results conclusively demonstrate that c-di-GMP does not function via a simple, low-specificity signaling pathway in V. cholerae .