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Stripping Bacillus: ComK auto-stimulation is responsible for the bistable response in competence development
Wiep Klaas Smits1, Caroline C Eschevins, Kim A Susanna
1Groningen Biomolecular Sciences and Biotechnology Institute, Department of Genetics, University of Groningen, Kerklaan 30, 9751 NN Haren, the Netherlands.
Molecular Microbiology
|April 12, 2005
Summary
Bacillus subtilis competence, a trait for genetic transformation, arises from ComK auto-stimulation. This mechanism, independent of other inputs, creates bistable expression, determining which cells develop competence.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Bacillus subtilis exhibits phenotypic heterogeneity in competence development for genetic transformation.
- The molecular basis for this heterogeneity in competence is not fully understood.
Purpose of the Study:
- To investigate the molecular mechanisms driving phenotypic heterogeneity in Bacillus subtilis competence.
- To identify the minimal regulatory requirements for competence development.
Main Methods:
- Stepwise simplification of the signal transduction cascade leading to competence.
- Analysis of ComK auto-stimulation as a potential driver of bistable gene expression.
Main Results:
- A simplified strain, lacking previously identified regulatory inputs, still develops competence.
- Auto-stimulation of ComK, the master regulator, is essential and sufficient for bistable competence gene expression.
- Transcriptional regulation defines the ComK threshold for auto-stimulation, while basal ComK levels (MecA-controlled) dictate the competent cell fraction.
Conclusions:
- ComK auto-stimulation is a key driver of phenotypic heterogeneity in Bacillus subtilis competence.
- The interplay between transcriptional regulation and basal ComK levels determines competence establishment in individual cells.