Structural determinants stabilizing the axial channel of ClpP for substrate translocation

Area of Science:

• Bacterial Proteolysis
• Antibiotic Mechanisms
• Structural Biology

Background:

• Acyldepsipeptides (ADEPs) are antibiotics that activate the ClpP protease in bacteria.
• ADEPs mimic interactions with ClpA/ClpX ATPases, opening the ClpP axial channel for substrate entry.
• Understanding ClpP gating is key to antibiotic mechanism and bacterial protein degradation.

Purpose of the Study:

• Identify structural determinants stabilizing the open conformation of the ClpP axial channel.
• Investigate the role of the N-terminal region in ClpP gate function.
• Elucidate conserved mechanisms of ClpP activation and gating.

Main Methods:

• Construction and analysis of ClpP variants with N-terminal amino acid substitutions.
• Investigating the role of a β-hairpin loop and hydrophobic cluster in axial gate function.
• Comparative analysis of ClpP from Escherichia coli and Bacillus subtilis.

Main Results:

• A β-hairpin loop in the N-terminal region is essential for axial gate opening.
• The integrity of a hydrophobic cluster at the loop's base is critical for efficient substrate translocation.
• These structural requirements for ClpP gating are conserved across bacterial species.

Conclusions:

• The N-terminal β-hairpin loop and associated hydrophobic cluster are key structural elements for ADEP-induced ClpP activation.
• These findings reveal conserved mechanisms governing ClpP protease gating and substrate translocation.
• Provides mechanistic insights into ADEP antibiotic action and bacterial protein homeostasis.