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A Fluorescence-based Method to Study Bacterial Gene Regulation in Infected Tissues
Published on: February 19, 2019
The LiaFSR system regulates the cell envelope stress response in Streptococcus mutans
Prashanth Suntharalingam1, M D Senadheera, Richard W Mair
1Dental Research Institute, Faculty of Dentistry, University of Toronto, 124 Edward St., Toronto, Ontario M5G1G6, Canada.
Journal of Bacteriology
|March 3, 2009
Summary
Streptococcus mutans uses the LiaFSR system to sense and respond to cell envelope stress, crucial for bacterial survival in the oral cavity. This system helps maintain cell integrity against environmental challenges.
Area of Science:
- Microbiology
- Bacterial Physiology
- Molecular Biology
Background:
- Cell envelope integrity is vital for bacterial survival, especially in dynamic environments like the human oral cavity.
- Streptococcus mutans, a key cause of dental caries, utilizes two-component signal transduction systems (TCSTSs) for environmental sensing.
- The LiaSR TCSTS in S. mutans is known to influence virulence factors such as acid tolerance and biofilm formation.
Purpose of the Study:
- To investigate the role of liaSR and its upstream gene liaF in the cell envelope stress response of Streptococcus mutans.
- To elucidate the function of the LiaFSR system in maintaining cell envelope integrity and bacterial tolerance to stress.
Main Methods:
- Transcriptional analysis to define the liaSR gene's operon structure.
- Phenotypic analysis of mutants deficient in liaFSR genes exposed to cell envelope antimicrobials and membrane-perturbing chemicals.
- Gene expression studies under stress conditions (e.g., bacitracin) to identify regulated pathways.
Main Results:
- LiaSR was confirmed as part of the pentacistronic liaFSR-ppiB-pnpB operon.
- Mutants lacking liaFSR genes exhibited increased susceptibility to antibiotics targeting the Lipid II cycle and chemicals disrupting cell membrane integrity.
- Bacitracin stress induced liaR transcription and the expression of genes involved in membrane synthesis, peptidoglycan biosynthesis, and stress response.
- LiaF demonstrated a regulatory role, repressing LiaR-regulated expression in the absence of stress and allowing derepression upon stress induction.
Conclusions:
- The LiaFSR system plays a novel and significant role in sensing cell envelope stress in Streptococcus mutans.
- LiaFSR is essential for preserving cell envelope integrity and bacterial survival under various environmental challenges.
- This study expands the understanding of bacterial stress response mechanisms, particularly in oral pathogens.
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