Abstract
Cold shock-domain family proteins (Csps) are highly conserved nucleic acid binding proteins regulating the expression of various genes including those involved in stress resistance and virulence in bacteria. We show here that Csps are involved in virulence, cell aggregation and flagella-based extracellular motility of Listeria monocytogenes. A L. monocytogenes mutant deleted in all three csp genes (ΔcspABD) is attenuated with respect to human macrophage infection as well as virulence in a zebrafish infection model. Moreover, this mutant is incapable of aggregation and fails to express surface flagella or exhibit swarming motility. An evaluation of double csp gene deletion mutant (ΔcspBD, ΔcspAD and ΔcspAB) strains that produce single csp genes showed that there is redundancy as well as functional differences among the three L. monocytogenes Csps in their contributions to virulence, cellular aggregation, flagella production, and swarming motility. Protein and mRNA expression analysis further showed impaired expression of key virulence and motility genes in the csp mutants. Our observations at protein and mRNA level suggest Csp-dependent expression regulation of these genes at transcriptional and post-transcriptional levels. In a mutant lacking all csp genes (ΔcspABD) as well as those possessing single csp genes (ΔcspBD, ΔcspAD, and ΔcspAB) we detected reduced levels of proteins or activity as well as transcripts from the prfA, hly, mpl, and plcA genes suggesting a Csp-dependent transcriptional regulation of these genes. These csp mutants also had reduced or completely lacked ActA proteins and cell surface flagella but contained elevated actA and flaA mRNA levels compared to the parental wild type strain suggesting Csp involvement in post-transcriptional regulation of these genes. Overall, our results suggest that Csps contribute to the expression regulation of virulence and flagella-associated genes thereby promoting host pathogenicity, cell aggregation and flagella-based motility processes in L. monocytogenes.
Highlights
The Gram-positive bacterium Listeria monocytogenes is an opportunistic foodborne pathogen that poses a serious public health risk if introduced into the food chain (Allerberger and Wagner, 2010; Anonymous, 2016)
Since the survival and multiplication of L. monocytogenes within target host cells is crucial step for successful host infections, we initially examined the functional contribution of Cold shock-domain family proteins (Csps) in this bacterium during human macrophage infection in cell culture
This suggests that both long-term growth and survival of L. monocytogenes inside human macrophages are significantly impaired without Csps (Figure 1A)
Summary
The Gram-positive bacterium Listeria monocytogenes is an opportunistic foodborne pathogen that poses a serious public health risk if introduced into the food chain (Allerberger and Wagner, 2010; Anonymous, 2016). The ingestion of contaminated food can lead to listeriosis, a disease associated with severe illnesses, high mortality, abortions, and stillbirths in susceptible or immunocompromised human individuals (Allerberger and Wagner, 2010; Silk et al, 2012) Besides these serious human health risks, listeriosis is responsible for significant food hygiene challenges and substantial economic losses to the food industry (Kramer et al, 2005; Jami et al, 2015; Melo et al, 2015). Various virulence factors mediate the invasion of L. monocytogenes into host cells and facilitate spread to neighboring cells (Dussurget, 2008; Freitag et al, 2009). Intracellular motility and cell-to-cell spread is mediated through the surface protein ActA and the internalin protein InlC (Kocks et al, 1992)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
