Cyclic di-GMP-Dependent Signaling Pathways in the Pathogenic Firmicute Listeria monocytogenes

Authors

Li-Hong Chen, University of Wyoming
Volkan K. Köseoğlu, University of Wyoming
Zehra T. Güvener, University of Wyoming
Tanya Myers-Morales, University of KentuckyFollow
Joseph M. Reed, University of Wyoming
Sarah E. F. D'Orazio, University of KentuckyFollow
Kurt W. Miller, University of Wyoming
Mark Gomelsky, University of Wyoming

Abstract

We characterized key components and major targets of the c-di-GMP signaling pathways in the foodborne pathogen Listeria monocytogenes, identified a new c-di-GMP-inducible exopolysaccharide responsible for motility inhibition, cell aggregation, and enhanced tolerance to disinfectants and desiccation, and provided first insights into the role of c-di-GMP signaling in listerial virulence. Genome-wide genetic and biochemical analyses of c-di-GMP signaling pathways revealed that L. monocytogenes has three GGDEF domain proteins, DgcA (Lmo1911), DgcB (Lmo1912) and DgcC (Lmo2174), that possess diguanylate cyclase activity, and three EAL domain proteins, PdeB (Lmo0131), PdeC (Lmo1914) and PdeD (Lmo0111), that possess c-di-GMP phosphodiesterase activity. Deletion of all phosphodiesterase genes (ΔpdeB/C/D) or expression of a heterologous diguanylate cyclase stimulated production of a previously unknown exopolysaccharide. The synthesis of this exopolysaccharide was attributed to the pssA-E (lmo0527-0531) gene cluster. The last gene of the cluster encodes the fourth listerial GGDEF domain protein, PssE, that functions as an I-site c-di-GMP receptor essential for exopolysaccharide synthesis. The c-di-GMP-inducible exopolysaccharide causes cell aggregation in minimal medium and impairs bacterial migration in semi-solid agar, however, it does not promote biofilm formation on abiotic surfaces. The exopolysaccharide also greatly enhances bacterial tolerance to commonly used disinfectants as well as desiccation, which may contribute to survival of L. monocytogenes on contaminated food products and in food-processing facilities. The exopolysaccharide and another, as yet unknown c-di-GMP-dependent target, drastically decrease listerial invasiveness in enterocytes in vitro, and lower pathogen load in the liver and gallbladder of mice infected via an oral route, which suggests that elevated c-di-GMP levels play an overall negative role in listerial virulence.

Document Type

Article

Publication Date

8-7-2014

Notes/Citation Information

Published in PLOS Pathogens, v. 10, no. 8, article e1004301, p. 1-15.

© 2014 Chen et al.

This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1371/journal.ppat.1004301

Funding Information

This work was supported in part by a Postdoctoral Fellowship from The China Scholarship Council (to LHC), and by grants from United States National Science Foundation (MCB1052575 to MG), National Institutes of Health (AI091918 to SEFD), and University of Wyoming Agriculture Experimental Station (to KWM and MG). JMR was a recipient of undergraduate research scholarships from the National Science Foundation Wyoming Experimental Program to Stimulate Competitive Research (EPSCoR) and the Wyoming National Aeronautics and Space Administration Space Grant Consortium. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Repository Citation

Chen, Li-Hong; Köseoğlu, Volkan K.; Güvener, Zehra T.; Myers-Morales, Tanya; Reed, Joseph M.; D'Orazio, Sarah E. F.; Miller, Kurt W.; and Gomelsky, Mark, "Cyclic di-GMP-Dependent Signaling Pathways in the Pathogenic Firmicute Listeria monocytogenes" (2014). Microbiology, Immunology, and Molecular Genetics Faculty Publications. 73.
https://uknowledge.uky.edu/microbio_facpub/73