Structural basis for the pore-forming activity of a complement-like toxin.

Area of Science:

• Microbiology
• Structural Biology
• Biochemistry

Background:

• Pore-forming proteins, including MACPF, CDC, and gasdermin superfamilies, create large pores.
• CDC-like proteins (CDCLs) are prevalent in gut microbes for antibacterial antagonism.
• The structural mechanism of CDCL pore formation is currently unknown.

Purpose of the Study:

• To elucidate the structural basis of CDCL pore formation.
• To provide detailed structural snapshots of the CDCL pore-forming pathway.
• To understand the regulatory features governing CDCL pore assembly.

Main Methods:

• Crystal structure determination of a proteolytically activated CDCL.
• Cryo-electron microscopy (cryo-EM) to resolve prepore and pore intermediates.
• Comparative structural analysis with known pore-forming protein families.

Main Results:

• Determined the crystal structure of an activated CDCL.
• Obtained cryo-EM structures of a prepore-like intermediate and a transmembrane pore.
• Revealed sophisticated regulatory features essential for productive pore formation.

Conclusions:

• CDCLs utilize a unique mechanism to assemble giant pores.
• The structural findings place CDCLs within the continuum of MACPF, CDC, and gasdermin pore superfamilies.
• This work clarifies the structural underpinnings of CDCL-mediated antibacterial antagonism.