ClpE from Lactococcus lactis promotes repression of CtsR-dependent gene expression

Area of Science:

• Bacteriology
• Molecular Biology
• Stress Response

Background:

• Bacterial heat shock response involves initial protein expression increase followed by adaptation.
• Heat shock regulators like CtsR control gene expression during stress.
• Clp ATPases are involved in protein degradation and cellular regulation.

Purpose of the Study:

• To investigate the role of Clp ATPase (ClpE) in the adaptation phase of the heat shock response in Lactococcus lactis.
• To determine how ClpE influences the expression of genes regulated by the heat shock regulator CtsR.
• To elucidate the mechanism by which ClpE contributes to turning off heat shock gene expression.

Main Methods:

• Northern blot analysis to assess clpP gene expression levels.
• Site-directed mutagenesis to study the function of conserved motifs in ClpE.
• Western blot analysis to quantify ClpE protein levels and processing.

Main Results:

• ClpE is required for the timely decrease in clpP gene expression after heat shock.
• Mutagenesis of the zinc-binding motif in ClpE impairs its ability to repress CtsR-dependent expression.
• ClpE undergoes ClpP-dependent processing at high temperatures, with the zinc finger domain influencing its stability.

Conclusions:

• ClpE plays a regulatory role in attenuating clpP gene expression following heat shock in Lactococcus lactis.
• The regulatory function of ClpE is likely mediated through its interaction with or regulation of CtsR.
• The zinc-binding domain of ClpE is important for its function in heat shock gene repression.