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DNA-affinity-purified Chip DAP-chip Method to Determine Gene Targets for Bacterial Two component Regulatory Systems
Published on: July 21, 2014
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Characterization of two co-regulated response regulators in Clostridioides difficile.
Caitlin Lee Williams1,2, Anchal Mehra2, Emily K Harrison2
1Department of Biology, Virginia Wesleyan University, Virginia Beach, Virginia, USA.
Journal of Bacteriology
|September 12, 2025
Summary
Clostridioides difficile regulators CmrR and CmrT form homodimers and potentially heterodimers. These regulators control key phenotypes and bind DNA, suggesting a role in transcriptional responses within the host gut environment.
Area of Science:
- Microbiology
- Bacterial Physiology
- Signal Transduction
Background:
- Clostridioides difficile is an anaerobic bacterium residing in the gut, requiring environmental sensing mechanisms.
- The cmrRST locus encodes an atypical two-component system with response regulators CmrR and CmrT.
- These regulators influence critical C. difficile phenotypes like motility and biofilm formation.
Purpose of the Study:
- To investigate the dimerization properties of CmrR and CmrT.
- To determine DNA-binding capabilities of CmrR.
- To understand the functional interactions within the CmrRST system.
Main Methods:
- Bacterial two-hybrid systems in Escherichia coli and Clostridioides difficile.
- Pull-down assays in Escherichia coli.
- Site-directed mutagenesis of CmrT active site residues.
Main Results:
- CmrR forms homodimers and binds a specific DNA sequence upstream of cmrRST.
- CmrT forms homodimers; significant reduction in activity requires multiple active site mutations.
- Evidence suggests CmrR and CmrT can form heterodimers, though functional significance is uncertain.
Conclusions:
- CmrR and CmrT dimerization is crucial for their function in C. difficile.
- The CmrRST system integrates environmental signals to regulate gene expression.
- This study elucidates novel regulatory mechanisms in C. difficile.
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