Cell envelope gene expression in phosphate-limited Bacillus subtilis cells.

Area of Science:

• Microbiology
• Molecular Biology
• Cell Biology

Background:

• Bacillus subtilis cell walls have high phosphate content, making cell wall metabolism crucial for the PhoPR-mediated phosphate limitation response.
• The WalRK two-component system uniquely regulates its regulon genes, including yocH and cwlO, with distinct expression patterns compared to other autolysin genes.

Purpose of the Study:

• To investigate the expression profiles of cell-envelope and PhoPR regulon genes in Bacillus subtilis under phosphate limitation.
• To understand the role of the PhoPR and WalRK two-component systems in regulating cell wall metabolism during phosphate stress.

Main Methods:

• Live cell array analysis
• Transcriptome analysis
• Gene expression profiling in exponentially growing and phosphate-limited B. subtilis cells.

Main Results:

• The PhoPR two-component system is activated specifically under phosphate limitation, showing rapid induction and sustained activity.
• Phosphate-limited cells exhibit altered expression of cell wall metabolism genes (MreBH, WapA, WprA) and sulfur metabolism genes.
• The WalRK system confers unique expression profiles on its regulon genes, with yocH and cwlO showing distinct regulation.

Conclusions:

• The PhoPR response significantly reshapes cell wall metabolism and gene expression in B. subtilis during phosphate limitation.
• Cell wall metabolism differs substantially between phosphate-limited and exponentially growing/stationary phases.
• The PhoPR response is rapidly reversible upon phosphate reintroduction, leading to increased cell wall metabolic gene expression.