Structure of the central Staphylococcus aureus AAA+ protease MecA/ClpC/ClpP

Area of Science:

• Molecular biology
• Structural biology
• Biochemistry

Background:

• Bacterial AAA+ proteases, like ClpC/ClpP, are vital for stress response and virulence.
• These proteases require adaptor proteins, such as MecA, for activation and complex assembly.

Purpose of the Study:

• To determine the cryo-electron microscopy (cryo-EM) structure of the MecA/ClpC/ClpP complex from Staphylococcus aureus.
• To elucidate the molecular mechanisms of substrate transfer and allosteric activation within this bacterial protease complex.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to visualize the MecA/ClpC/ClpP complex.
• Structural analysis to identify key interaction interfaces and functional domains.

Main Results:

• The structure shows MecA positioned to facilitate substrate transfer to ClpC.
• ClpC P-loops and ClpP β-hairpins mediate complex formation and interact within the ClpC channel.
• ClpP binding allosterically enhances ClpC's ATPase and threading activities in a β-hairpin-dependent manner.

Conclusions:

• The MecA/ClpC/ClpP structure reveals an intricate mechanism for substrate processing in bacterial AAA+ proteases.
• Allosteric regulation via ClpP binding is critical for coordinating the activities of the ATPase and peptidase components.