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Bacillus subtilis DesR functions as a phosphorylation-activated switch to control membrane lipid fluidity
Larisa E Cybulski1, Gloria del Solar, Patricio O Craig
1Instituto de Biología Molecular y Celular de Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Departamento de Microbiología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Argentina.
The Journal of Biological Chemistry
|July 13, 2004
Summary
Phosphorylation activates the DesR transcription factor, enabling it to bind DNA and regulate cold-shock gene expression in Bacillus subtilis. This mechanism optimizes membrane fluidity by controlling Delta5-fatty acid desaturase synthesis.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- The Des pathway in Bacillus subtilis controls cold-shock adaptation.
- DesK kinase activates DesR response regulator upon decreased membrane fluidity.
- The precise DNA-binding mechanism of DesR remained unclear.
Purpose of the Study:
- To elucidate the phosphorylation-dependent DNA-binding mechanism of DesR.
- To understand how DesR regulates the Delta5-fatty acid desaturase (Delta5-Des) gene expression.
Main Methods:
- Biochemical assays to study protein-DNA interactions.
- Analysis of DesR phosphorylation and its effect on DNA binding.
- Investigating the cooperative binding of DesR to regulatory DNA sites.
Main Results:
- Only phosphorylated DesR (DesR-P) binds to the Pdes regulatory region.
- DesR-P binds cooperatively to two distinct DNA sites, shifting to a tetrameric form.
- This leads to RNA polymerase recruitment and activation of the des gene.
Conclusions:
- DesR acts as a phosphorylation-activated switch for cold-shock gene regulation.
- This mechanism allows Bacillus subtilis to optimize membrane phospholipid fluidity.
- Provides the first detailed example of this regulatory strategy for a cold-shock gene.