Project description:In this study we determined the gene expression of THP-1 derived macrophages during the interaction with V. cholerae wildtype cells, biofilm-deficient or hemolysin-deficient mutants.
Project description:Biofilm formation is generally recognized as a bacterial defense mechanism against environmental threats, including antibiotics, bacteriophages, and leukocytes of the human immune system. Here, we show that for the human pathogen Vibrio cholerae, biofilm formation is not only a protective trait, but also an aggressive trait to collectively predate different types of immune cells. We find that V. cholerae forms biofilms on the eukaryotic cell surface using an extracellular matrix comprising primarily mannose-sensitive hemagglutinin pili, toxin-coregulated pili, and the secreted colonization factor TcpF, which is distinct from the matrix composition of biofilms on abiotic surfaces. These biofilms encase immune cells and establish a high local concentration of a secreted hemolysin to kill the immune cells, before the biofilms disperse in a c-di-GMP-dependent manner. Together, these results uncover a mechanism for how bacteria employ biofilm formation as a multicellular strategy to invert the typical relationship between the human immune system as the hunter and bacteria as the hunted.
Project description:Biofilm formation is generally recognized as a bacterial defense mechanism against environmental threats, including antibiotics, bacteriophages, and leukocytes of the human immune system. Here, we show that for the human pathogen Vibrio cholerae, biofilm formation is not only a protective trait, but also an aggressive trait to collectively predate different types of immune cells. We find that V. cholerae forms biofilms on the eukaryotic cell surface using an extracellular matrix comprising primarily mannose-sensitive hemagglutinin pili, toxin-coregulated pili, and the secreted colonization factor TcpF, which is distinct from the matrix composition of biofilms on abiotic surfaces. These biofilms encase immune cells and establish a high local concentration of a secreted hemolysin to kill the immune cells, before the biofilms disperse in a c-di-GMP-dependent manner. Together, these results uncover a mechanism for how bacteria employ biofilm formation as a multicellular strategy to invert the typical relationship between the human immune system as the hunter and bacteria as the hunted.
Project description:Cholera is a deadly diarrheal disease that affects millions of people globally. Although V. cholerae, the causative agent of the disease, has been extensively studied in isolation, it was relatively recently that scientists started investigating its interactions with the gut microbiota. Our group and others previously showed that microbiota-derived metabolites significantly influence V. cholerae behavior. By investigating how an organic extract of human feces affects V. cholerae gene expression, we recently showed that gut metabolites strongly suppress swimming motility, a virulence factor important for host colonization. Interestingly, extracts of pure cultures of a single gut commensal, Enterocloster citroniae, recapitulated this inhibitory effect. Here, we present a comprehensive examination of the effect of small molecules produced by E. citroniae and related species on V. cholerae behavior. We show that E. citroniae small molecules inhibit motility by various V. cholerae strains. We also show that several phylogenetically related species produce this activity, although the magnitude of the effect varies between strains. Using biofilm formation assays in static and shear flow conditions, we show that V. cholerae strongly induces biofilm formation in response to E. citroniae metabolites. Transcriptome and reporter analyses show that several genes involved in the synthesis of an extracellular polysaccharide are induced by growth in the presence of E. citroniae metabolites. Lastly, we show that V. cholerae interactions with host epithelial cells are also modulated by compounds produced by this commensal. These findings advance our understanding of microbiome-pathogen interactions and how commensal bacteria influence V. cholerae virulence through the production of small molecules. In the future, this knowledge may be used to design novel microbiome-based therapeutic approaches to combat cholera and other infections.
Project description:Biofilms are matrix-encased microbial communities that increase the environmental fitness and infectivity of many human pathogens including Vibrio cholerae. Biofilm matrix assembly is essential for biofilm formation and function. Known components of the V. cholerae biofilm matrix are the polysaccharide VPS, matrix proteins RbmA, RbmC, Bap1, and extracellular DNA, but the majority of the protein composition is uncharacterized. This study comprehensively analyzed the biofilm matrix proteome and revealed the presence of outer membrane proteins (OMPs). Outer membrane vesicles (OMVs) were also present in the V. cholerae biofilm matrix and were associated with OMPs and many biofilm matrix proteins suggesting that they participate in biofilm matrix assembly. Consistent with this, OMVs had the capability to alter biofilm structural properties depending on their composition. OmpU was the most prevalent OMP in the matrix, and its absence altered biofilm architecture by increasing VPS production. Using single-cell force spectroscopy, we further showed that OmpU, the matrix proteins RbmA, RbmC, and Bap1, and VPS contribute to cell-surface adhesion forces, which are critical for biofilm formation. Our findings provide new insights into the molecular mechanisms underlying biofilm matrix assembly in V. cholerae, which may open up new opportunities to develop inhibitors that specifically alter biofilm matrix properties and, thus, affect either the environmental survival or pathogenesis of Vibrio cholerae.
Project description:Biofilms are matrix-encased microbial communities that increase the environmental fitness and infectivity of many human pathogens including Vibrio cholerae. Biofilm matrix assembly is essential for biofilm formation and function. Known components of the V. cholerae biofilm matrix are the polysaccharide VPS, matrix proteins RbmA, RbmC, Bap1, and extracellular DNA, but the majority of the protein composition is uncharacterized. This study comprehensively analyzed the biofilm matrix proteome and revealed the presence of outer membrane proteins (OMPs). Outer membrane vesicles (OMVs) were also present in the V. cholerae biofilm matrix and were associated with OMPs and many biofilm matrix proteins suggesting that they participate in biofilm matrix assembly. Consistent with this, OMVs had the capability to alter biofilm structural properties depending on their composition. OmpU was the most prevalent OMP in the matrix, and its absence altered biofilm architecture by increasing VPS production. Single-cell force spectroscopy revealed that proteins critical for biofilm formation, OmpU, the matrix proteins RbmA, RbmC, Bap1, and VPS, contribute to cell-surface adhesion forces at differing efficiency, with VPS showing the highest efficiency whereas Bap1 showing the lowest efficiency. Our findings provide new insights into the molecular mechanisms underlying biofilm matrix assembly in V. cholerae, which may provide new opportunities to develop inhibitors that specifically alter biofilm matrix properties and, thus, affect either the environmental survival or pathogenesis of V. cholerae.
Project description:To determine transcriptome differences in Vibrio cholerae when grown as planktonic and biofilm cultures, whole-genome level transcriptional profiling was performed using RNAseq analysis. Transcriptomes of biofim and planktonic cultures were compared in this study.
Project description:The global transcriptional regulator Hha of Escherichia coli controls hemolysin activity, biofilm formation, and virulence expressions. Earlier, we have reported that Hha represses initial biofilm formation and disperses biofilms as well as controls prophage excision in E. coli. Since biofilm dispersal is a promising area to control biofilms, here we rewired Hha to control biofilm dispersal and formation. The Hha variant Hha13D6 was obtained to have enhanced biofilm dispersal activity along with increased toxicity compared to wild-type Hha (Hha13D6 induces dispersal 60%, whereas wild-type Hha induces dispersal at early biofilms but not at mature biofilms). Toxic Hha13D6 caused cell death probably by the activation of proteases HslUV, Lon, and PrlC, and deletion of protease gene hslV with overproducing Hh13D6 repressed biofilm dispersal, indicating Hha13D6 induces biofilm dispersal through the activity of protease HslV. Furthermore, another Hha variant Hha24E9 was also obtained to decrease biofilm formation 4-fold compared to wild-type Hha by regulation of gadW, glpT, and phnF. However, the dispersal variant Hha13D6 did not decrease biofilm formation, while the biofilm variant Hha24E9 did not induce biofilm dispersal. Hence, Hha may have evolved two ways in response to environmental factors to control biofilm dispersal and formation, but both controlling mechanisms come from different regulatory systems.
Project description:The cholera disease bacterium V. cholerae, can adopt planktonic or biofilm lifestyles depending on the intracellular concentration of the second messenger cyclic diguanylic acid (c-di-GMP). Biofilm formation protects Vibrios from stressful conditions and facilitates disease transmission by enhancing infectivity. The histone-like nucleoid structuring protein (H-NS) is a global regulator of genes associated with pathogenicity and responses to environmental stresses. H-NS represses the transcription of genes vpsT, vpsA and vpsL, which are required for the biosynthesis of the biofilm exopolysacchide matrix. Here we demonstrate that the c-di-GMP-binding protein VpsT disrupts H-NS nucleoprotein complexes at the vpsA and vpsL promoters and that this effect is enhanced by c-di-GMP. We used ChIP coupled with Next Generation Sequencing (ChIP-Seq) and transcriptome analysis (RNA-Seq) to identify additional loci repressed by H-NS affecting biofilm formation. This study showed that H-NS directly represses the transcription of genes encoding proteins present in the biofilm matrix such as the rbmA-F cluster, hemolysin and chitinase. Similar to vpsA and vpsL, the promoter region of vpsU, rbmA and rbmF exhibited overlapping H-NS and VpsT binding motifs. Deletion of vpsT increased H-NS occupancy at the vpsU, vpsA, vpsL, rbmA and rbmF promoters. Conversely, artificially increasing the c-di-GMP pool diminished H-NS occupancy at the above promoters. Deletion of vpsT did not affect H-NS occupancy at its own promoter. However, deletion of genes encoding the regulators AphA and VpsR significantly increased H-NS occupancy at the vpsT promoter. In sum, our study shows that c-di-GMP enhances biofilm formation by acting through VpsT to activate an H-NS anti-repression cascade. The Binding profile of V. cholerae H-NS to the genome was determined by ChIP followed by Next Generation Sequencing (ChIP-Seq) using the Illumina HiSeq2000 platform. V. cholerae C7258 cells expressing H-NS-FLAG fusion protein from the hns transcription and translation signals were collected from LB cultures grown to mid-exponential phase (OD600 0.5). An anti-FLAG Immunoprecipitation (IP) and an Input samples were used for the analysis.
Project description:Enterocloster citroniae and related gut microbiome species modulate Vibrio cholerae biofilm formation through the production of bioactive small molecules