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Genome-wide DNA-binding profile of the Vibrio cholerae histone-like nucleoid structuring protein (H-NS)

ABSTRACT: 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.

ORGANISM(S): Vibrio cholerae

PROVIDER: GSE64249 | GEO | 2015/05/13

SECONDARY ACCESSION(S): PRJNA270531

REPOSITORIES: GEO

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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:The global regulator, H-NS, controls genes related to stress response, biofilm formation, and virulence expression by recognizing the curved DNA and silences gene transcription acquired from lateral gene transfer. Here, we rewired H-NS to control biofilm formation using protein engineering. One H-NS variant, H-NS K57N was obtained to reduce biofilm formation 10-fold compared to H-NS wild-type. Whole-transcriptome analysis (BW25113 hha hns / pCA24N-hns K57N vs. BW25113 hha hns / pCA24N-hns) revealed that H-NS K57N represses biofilm formation through the interactinon with other nucleoid proteins, Cnu and StpA. Remarkably, H-NS K57N enhanced the excision of defective prophage Rac while H-NS wild-type represses it, and H-NS controlled only Rac excision among E. coli prophages. These results imply that the repression of Rac excision is one of the silencing manner for foreign genes by H-NS. Also, the prophage excision not only led to the change of biofilm formation but also resulted in cell lysis through the expression of toxin protein HokD with reduced viability, which are important for cell physiology in response to the change of environmental conditions. Hence, H-NS regulatory system may be evolved easily with specialized functions in terms of biofilm formation, prophage control, and cell lysis. For the whole transcriptome study of BW25113 hha hns / pCA24N-hns K57N versus BW25113 hha hns / pCA24N-hns, cells were grown in 250 mL LB containing 1 mM IPTG for 7 h with 10 g of glass wool (Corning Glass Works, Corning, N.Y.) in 1 L Erlenmeyer flasks to form a robust biofilm. Biofilm cells were obtained by rinsing and sonicating the glass wool in sterile 0.85% NaCl solution at 0Â°C, and RNALater bufferÂ® (Applied Biosystems, Foster City, CA) was added for RNA stabilization and protection during the RNA preparation steps. Total RNA was isolated from biofilm cells. The E. coli GeneChip Genome 2.0 array (Affymetrix, Lot# 4059655) containing 10,208 probe sets for four E. coli strains (MG1655, CFT073, O157:H7-Sakai, and O157:H7-EDL933) was used for DNA microarray. cDNA synthesis, fragmentation, and hybridizations were performed.

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Genome-wide DNA-binding profile of the Vibrio cholerae histone-like nucleoid structuring protein (H-NS)

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