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Conditions that induce Staphylococcus aureus heat shock proteins also inhibit autolysis
M W Qoronfleh1, J E Gustafson, B J Wilkinson
1Department of Biological Sciences, Illinois State University, Normal 61790-4120, USA.
FEMS Microbiology Letters
|September 19, 1998
Summary
Heat shock reduces Staphylococcus aureus cell autolysis by impairing autolysin activity. This finding may influence understanding of bacterial cell wall metabolism and antibiotic resistance mechanisms.
Area of Science:
- Microbiology
- Bacterial Physiology
- Molecular Biology
Background:
- Staphylococcus aureus autolysis is crucial for cell wall remodeling and antibiotic resistance.
- Heat shock response is a cellular defense mechanism against environmental stress.
Purpose of the Study:
- To investigate the effect of heat shock on Staphylococcus aureus cell autolysis.
- To explore the underlying mechanisms of heat shock-induced changes in autolytic activity.
Main Methods:
- Staphylococcus aureus strain 8325 was subjected to heat shock (40°C) and other stress agents (CdCl2, ethanol, NaCl).
- Cell autolysis rates were measured in buffer with and without Triton X-100.
- Freeze-thaw autolysin activity on purified cell walls was assessed.
- Autolytic activity of isolated cell walls was determined.
- Peptidoglycan hydrolase activity profiles were analyzed using renaturing SDS-PAGE.
Main Results:
- Heat shock significantly reduced the rate of cell autolysis in Staphylococcus aureus.
- Cells treated with other stress agents also exhibited decreased autolysis.
- Heat-shocked cells showed reduced freeze-thaw autolysin activity and lower autolytic activity in isolated cell walls.
- No differences in peptidoglycan hydrolase activity profiles were observed between control and heat-shocked cells.
Conclusions:
- Heat shock impairs Staphylococcus aureus autolysin activity, potentially by damaging autolysins or inhibiting their targeting to the cell wall.
- Heat shock proteins may complex with autolysins, inhibiting their function.
- Heat shock also reduced autolytic activity in methicillin-resistant and susceptible strains, suggesting a potential link to methicillin resistance expression.