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Identification of a membrane-bound transcriptional regulator that links chitin and natural competence in Vibrio cholerae
- Source :
- mBio, mBio, Vol 5, Iss 1 (2014)
- Publication Year :
- 2014
-
Abstract
- Vibrio cholerae is naturally competent when grown on chitin. It is known that expression of the major regulator of competence, TfoX, is controlled by chitin; however, the molecular mechanisms underlying this requirement for chitin have remained unclear. In the present study, we identify and characterize a membrane-bound transcriptional regulator that positively regulates the small RNA (sRNA) TfoR, which posttranscriptionally enhances tfoX translation. We show that this regulation of the tfoR promoter is direct by performing electrophoretic mobility shift assays and by heterologous expression of this system in Escherichia coli. This transcriptional regulator was recently identified independently and was named “TfoS” (S. Yamamoto et al., Mol. Microbiol., in press, doi:10.1111/mmi.12462). Using a constitutively active form of TfoS, we demonstrate that the activity of this regulator is sufficient to promote competence in V. cholerae in the absence of chitin. Also, TfoS contains a large periplasmic domain, which we hypothesized interacts with chitin to regulate TfoS activity. In the heterologous host E. coli, we demonstrate that chitin oligosaccharides are sufficient to activate TfoS activity at the tfoR promoter. Collectively, these data characterize TfoS as a novel chitin-sensing transcriptional regulator that represents the direct link between chitin and natural competence in V. cholerae.<br />IMPORTANCE Naturally competent bacteria can take up exogenous DNA from the environment and integrate it into their genome by homologous recombination. This ability to take up exogenous DNA is shared by diverse bacterial species and serves as a mechanism to acquire new genes to enhance the fitness of the organism. Several members of the family Vibrionaceae become naturally competent when grown on chitin; however, a molecular understanding of how chitin activates competence is lacking. Here, we identify a novel membrane-bound transcriptional regulator that is required for natural transformation in the human pathogen Vibrio cholerae. We demonstrate that this regulator senses chitin oligosaccharides to activate the competence cascade, thus, uncovering the molecular link between chitin and natural competence in this Vibrio species.
- Subjects :
- DNA, Bacterial
Regulator
Chitin
Electrophoretic Mobility Shift Assay
macromolecular substances
Biology
medicine.disease_cause
Microbiology
03 medical and health sciences
chemistry.chemical_compound
Virology
medicine
Transcriptional regulation
Escherichia coli
Vibrio cholerae
030304 developmental biology
Regulation of gene expression
0303 health sciences
030306 microbiology
DNA Transformation Competence
fungi
Natural competence
Gene Expression Regulation, Bacterial
QR1-502
Recombinant Proteins
Cell biology
carbohydrates (lipids)
chemistry
Heterologous expression
Protein Binding
Transcription Factors
Research Article
Subjects
Details
- ISSN :
- 21507511
- Volume :
- 5
- Issue :
- 1
- Database :
- OpenAIRE
- Journal :
- mBio
- Accession number :
- edsair.doi.dedup.....67dfa9e0542a0c90d1a27f004e86584f