Two nucleotide second messengers regulate the production of the Vibrio cholerae colonization factor GbpA

Abstract

BackgroundThe nucleotide second messengers cAMP and c-di-GMP allow many bacteria, including the human intestinal pathogen Vibrio cholerae, to respond to environmental stimuli with appropriate physiological adaptations. In response to limitation of specific carbohydrates, cAMP and its receptor CRP control the transcription of genes important for nutrient acquisition and utilization; c-di-GMP controls the transition between motile and sessile lifestyles often, but not exclusively, through transcriptional mechanisms. In this study, we investigated the convergence of cAMP and c-di-GMP signaling pathways in regulating the expression of gbpA. GbpA is a colonization factor that participates in the attachment of V. cholerae to N-acetylglucosamine-containing surfaces in its native aquatic environment and the host intestinal tract.ResultsWe show that c-di-GMP inhibits gbpA activation in a fashion independent of the known transcription factors that directly sense c-di-GMP. Interestingly, inhibition of gbpA activation by c-di-GMP only occurs during growth on non-PTS dependent nutrient sources. Consistent with this result, we show that CRP binds to the gbpA promoter in a cAMP-dependent manner in vitro and drives transcription of gbpA in vivo. The interplay between cAMP and c-di-GMP does not broadly impact the CRP-cAMP regulon, but occurs more specifically at the gbpA promoter.ConclusionsThese findings suggest that c-di-GMP directly interferes with the interaction of CRP-cAMP and the gbpA promoter via an unidentified regulator. The use of two distinct second messenger signaling mechanisms to regulate gbpA transcription may allow V. cholerae to finely modulate GbpA production, and therefore colonization of aquatic and host surfaces, in response to discrete environmental stimuli.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-015-0506-5) contains supplementary material, which is available to authorized users.

A Nutrient-Regulated Cyclic Diguanylate Phosphodiesterase Controls Clostridium difficile Biofilm and Toxin Production during Stationary Phase

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“…Genome neighborhood analysis revealed that gbpA is near two c-di-GMP binding riboswitches called Vc1 and Vc2 (130). A recent study confirmed that the second messengers c-di-GMP and cyclic AMP (cAMP) regulate gbpA transcription (131). The levels of c-di-GMP and cAMP are regulated by numerous abiotic signals, confirming that GbpA expression is fine-tuned in response to environmental signals (131).…”