scholarly journals The Second Type VI Secretion System ofPseudomonas aeruginosaStrain PAO1 Is Regulated by Quorum Sensing and Fur and Modulates Internalization in Epithelial Cells

2012 ◽  
Vol 287 (32) ◽  
pp. 27095-27105 ◽  
Author(s):  
Thibault G. Sana ◽  
Abderrahman Hachani ◽  
Iwona Bucior ◽  
Chantal Soscia ◽  
Steve Garvis ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Quorum Sensing ◽  
Secretion System ◽  
Type Vi Secretion System ◽  
Type Vi Secretion

scholarly journals Expression of the Type VI Secretion System 1 Component Hcp1 Is Indirectly Repressed by OpaR inVibrio parahaemolyticus

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Lizhi Ma ◽  
Yiquan Zhang ◽  
Xiaojuan Yan ◽  
Liping Guo ◽  
Li Wang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Stress Responses ◽  
Structural Component ◽  
Vibrio Parahaemolyticus ◽  
Secretion System ◽  
Upstream Region ◽  
Bacterial Protein ◽  
Type Vi Secretion System ◽  
Type Vi Secretion ◽  
System 1

The type VI secretion system (T6SS) is bacterial protein injection machinery with roles in virulence, symbiosis, interbacterial interaction, antipathogenesis, and environmental stress responses. There are two T6SS loci, T6SS1 and T6SS2, in the two chromosomes ofVibrio parahaemolyticus, respectively. This work disclosed that the master quorum sensing (QS) regulator OpaR repressed the transcription ofhcp1encoding the structural component Hcp1 of T6SS1 inV. parahaemolyticus, indicating that QS had a negative regulatory action on T6SS1. A singleσ54-dependent promoter was transcribed forhcp1inV. parahaemolyticus, and its activity was repressed by the OpaR regulator. Since the OpaR protein could not bind to the upstream region ofhcp1, OpaR would repress the transcription ofhcp1in an indirect manner.

scholarly journals The Type VI Secretion System Plays a Role in Type 1 Fimbria Expression and Pathogenesis of an Avian Pathogenic Escherichia coli Strain

2010 ◽  
Vol 78 (12) ◽  
pp. 4990-4998 ◽  
Author(s):  
Fernanda de Pace ◽  
Gerson Nakazato ◽  
Alline Pacheco ◽  
Jacqueline Boldrin de Paiva ◽  
Vanessa Sperandio ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Disease Process ◽  
Secretion System ◽  
Coli Strain ◽  
Economic Losses ◽  
Type Vi Secretion System ◽  
Type 1 Fimbriae ◽  
Type Vi Secretion

ABSTRACT Avian pathogenic Escherichia coli (APEC) strains frequently cause extraintestinal infections and are responsible for significant economic losses in the poultry industry worldwide. APEC isolates are closely related to human extraintestinal pathogenic E. coli (ExPEC) strains and may also act as pathogens for humans. Known APEC virulence factors include adhesins such as type 1 fimbriae and curli, iron acquisition systems, and cytotoxins. Here we show that APEC strain SEPT362, isolated from a septicemic hen, expresses a type VI secretion system (T6SS); causes cytoskeleton rearrangements; and invades epithelial cells, replicates within macrophages, and causes lethal disease in chicks. To assess the contribution of the T6SS to SEPT362 pathogenesis, we generated two mutants, hcp (which encodes a protein suggested to be both secreted and a structural component of the T6SS) and clpV (encoding the T6SS ATPase). Both mutants showed decreased adherence and actin rearrangement on epithelial cells. However, only the hcp mutant presented a mild decrease in its ability to invade epithelial cells, and none of these mutants were defective for intramacrophage replication. Transcriptome studies showed that the level of expression of type 1 fimbriae was decreased in these mutants, which may account for the diminished adhesion and invasion of epithelial cells. The T6SS seems to be important for the disease process, given that both mutants were attenuated for infection in chicks. These results suggest that the T6SS influences the expression of type 1 fimbriae and contributes to APEC pathogenesis.

scholarly journals RpoN-Dependent Direct Regulation of Quorum Sensing and the Type VI Secretion System inPseudomonas aeruginosaPAO1

2018 ◽  
Vol 200 (16) ◽  
Author(s):  
Xiaolong Shao ◽  
Xiaoning Zhang ◽  
Yingchao Zhang ◽  
Miao Zhu ◽  
Pan Yang ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
High Throughput Sequencing ◽  
Functional Characterization ◽  
Secretion System ◽  
Global Regulator ◽  
Type Vi Secretion System ◽  
Related Factors ◽  
Content Type ◽  
Type Vi Secretion ◽  
Wide Range

ABSTRACTPseudomonas aeruginosais a Gram-negative opportunistic pathogen of humans, particularly those with cystic fibrosis. As a global regulator, RpoN controls a group of virulence-related factors and quorum-sensing (QS) genes inP. aeruginosa. To gain further insights into the direct targets of RpoNin vivo, the present study focused on identifying the direct targets of RpoN regulation in QS and the type VI secretion system (T6SS). We performed chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) that identified 1,068 binding sites of RpoN, mostly including metabolic genes, a group of genes in QS (lasI,rhlI, andpqsR) and the T6SS (hcpAandhcpB). The direct targets of RpoN have been verified by electrophoretic mobility shifts assays (EMSA),luxreporter assay, reverse transcription-quantitative PCR, and phenotypic detection. TheΔrpoN::Tc mutant resulted in the reduced production of pyocyanin, motility, and proteolytic activity. However, the production of rhamnolipids and biofilm formation were higher in theΔrpoN::Tc mutant than in the wild type. In summary, the results indicated that RpoN had direct and profound effects on QS and the T6SS.IMPORTANCEAs a global regulator, RpoN controls a wide range of biological pathways, including virulence inP. aeruginosaPAO1. This work shows that RpoN plays critical and global roles in the regulation of bacterial pathogenicity and fitness. ChIP-seq provided a useful database to characterize additional functions and targets of RpoN in the future. The functional characterization of RpoN-mediated regulation will improve the current understanding of the regulatory network of quorum sensing and virulence inP. aeruginosaand other bacteria.

scholarly journals N-Acylhomoserine lactones involved in quorum sensing control the type VI secretion system, biofilm formation, protease production, and in vivo virulence in a clinical isolate of Aeromonas hydrophila

Microbiology ◽  
2009 ◽  
Vol 155 (11) ◽  
pp. 3518-3531 ◽  
Author(s):  
Bijay K. Khajanchi ◽  
Jian Sha ◽  
Elena V. Kozlova ◽  
Tatiana E. Erova ◽  
Giovanni Suarez ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Aeromonas Hydrophila ◽  
Biofilm Formation ◽  
Secretion System ◽  
Protease Production ◽  
Type Vi Secretion System ◽  
Double Knockout ◽  
Electron Microscopic ◽  
Type Vi Secretion

In this study, we delineated the role of N-acylhomoserine lactone(s) (AHLs)-mediated quorum sensing (QS) in the virulence of diarrhoeal isolate SSU of Aeromonas hydrophila by generating a double knockout ΔahyRI mutant. Protease production was substantially reduced in the ΔahyRI mutant when compared with that in the wild-type (WT) strain. Importantly, based on Western blot analysis, the ΔahyRI mutant was unable to secrete type VI secretion system (T6SS)-associated effectors, namely haemolysin coregulated protein and the valine-glycine repeat family of proteins, while significant levels of these effectors were detected in the culture supernatant of the WT A. hydrophila. In contrast, the production and translocation of the type III secretion system (T3SS) effector AexU in human colonic epithelial cells were not affected when the ahyRI genes were deleted. Solid surface-associated biofilm formation was significantly reduced in the ΔahyRI mutant when compared with that in the WT strain, as determined by a crystal violet staining assay. Scanning electron microscopic observations revealed that the ΔahyRI mutant was also defective in the formation of structured biofilm, as it was less filamentous and produced a distinct exopolysaccharide on its surface when compared with the structured biofilm produced by the WT strain. These effects of AhyRI could be complemented either by expressing the ahyRI genes in trans or by the exogeneous addition of AHLs to the ΔahyRI/ahyR+ complemented strain. In a mouse lethality experiment, 50 % attenuation was observed when we deleted the ahyRI genes from the parental strain of A. hydrophila. Together, our data suggest that AHL-mediated QS modulates the virulence of A. hydrophila SSU by regulating the T6SS, metalloprotease production and biofilm formation.

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