A Multimodal Strategy Used by a Large c-di-GMP Network

Area of Science:

• Microbiology
• Molecular Biology
• Systems Biology

Background:

• Cyclic diguanylate (c-di-GMP) is a crucial second messenger regulating bacterial biofilm formation.
• Microbes possess extensive protein networks for c-di-GMP synthesis, degradation, and binding.
• Understanding signaling specificity within these networks is a key challenge.

Purpose of the Study:

• To investigate the Pseudomonas fluorescens c-di-GMP signaling network.
• To determine how nutrient availability impacts biofilm formation via c-di-GMP.
• To elucidate the regulatory mechanisms governing c-di-GMP signaling.

Main Methods:

• Systematic analysis of over 50 predicted c-di-GMP proteins across 188 nutrient conditions.
• Transcriptional profiling of network members under approximately 50 nutrient conditions.
• Bacterial two-hybrid assays to map approximately 2,000 protein-protein interactions.

Main Results:

• A majority of c-di-GMP enzymes and effectors influence biofilm formation in a context-dependent manner.
• Nutrient-induced gene expression explains some, but not all, biofilm responses.
• Multimodal regulation involving ligand sensing, protein interactions, and transcriptional control fine-tunes c-di-GMP responses.

Conclusions:

• The Pseudomonas fluorescens c-di-GMP network employs a sophisticated regulatory strategy for cellular decision-making.
• Combinations of signaling pathways ensure precise control over biofilm formation.
• This work provides a foundation for modeling and engineering bacterial signaling circuitry.