The Pseudomonas aeruginosa sensor RetS switches Type III and Type VI secretion via c-di-GMP signalling
Article first published online: 28 SEP 2011
© 2011 Society for Applied Microbiology and Blackwell Publishing Ltd
Thematic Issue: Human Microbiome
Volume 13, Issue 12, pages 3128–3138, December 2011
How to Cite
Moscoso, J. A., Mikkelsen, H., Heeb, S., Williams, P. and Filloux, A. (2011), The Pseudomonas aeruginosa sensor RetS switches Type III and Type VI secretion via c-di-GMP signalling. Environmental Microbiology, 13: 3128–3138. doi: 10.1111/j.1462-2920.2011.02595.x
- Issue published online: 30 NOV 2011
- Article first published online: 28 SEP 2011
- Received 21 March 2011; accepted 15 August 2011.
Acute bacterial infections are associated with motility and cytotoxicity via the type III secretion system (T3SS), while chronic infections are linked to biofilm formation and reduced virulence. In Pseudomonas aeruginosa, the transition between motility and sessility involves regulatory networks including the RetS/GacS sensors, as well as the second messenger c-di-GMP. The RetS/GacS signalling cascade converges on small RNAs, RsmY and RsmZ, which control a range of functions via RsmA. A retS mutation induces biofilm formation, and high levels of c-di-GMP produce a similar response. In this study, we connect RetS and c-di-GMP pathways by showing that the retS mutant displays high levels of c-di-GMP. Furthermore, a retS mutation leads to repression of the T3SS, but also upregulates the type VI secretion system (T6SS), which is associated with chronic infections. Strikingly, production of the T3SS and T6SS can be switched by artificially modulating c-di-GMP levels. We show that the diguanylate cyclase WspR is specifically involved in the T3SS/T6SS switch and that RsmY and RsmZ are required for the c-di-GMP-dependent response. These results provide a firm link between the RetS/GacS and the c-di-GMP pathways, which coordinate bacterial lifestyles, as well as secretion systems that determine the infection strategy of P. aeruginosa.