Bacillus subtilis CodY represses early-stationary-phase genes by sensing GTP levels

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Genetics

Background:

• CodY is a conserved protein in low G+C, gram-positive bacteria.
• It regulates genes involved in the transition from exponential growth to stationary phase and sporulation in Bacillus subtilis.
• This transition is linked to a decrease in intracellular guanosine triphosphate (GTP).

Purpose of the Study:

• To investigate the role of CodY in regulating stationary-phase genes.
• To determine if CodY's function is mediated by intracellular GTP levels.
• To understand CodY's role in preventing sporulation under nutrient-rich conditions.

Main Methods:

• In vitro GTP-binding assays for CodY.
• Analysis of gene expression in wild-type and codY-null mutant Bacillus subtilis strains.
• Treatment with decoyinine, a GMP synthetase inhibitor, to mimic GTP depletion.

Main Results:

• CodY binds GTP in vitro.
• CodY-mediated repression of gene promoters is dependent on high GTP concentrations.
• A codY-null mutant sporulated under nutrient excess, indicating CodY normally prevents this.

Conclusions:

• Bacillus subtilis CodY is a novel GTP-binding protein.
• CodY acts as a nutrient sensor by monitoring intracellular GTP levels.
• CodY regulates the transcription of early-stationary-phase and sporulation genes for adaptation to nutrient limitation.