Clostridium perfringens enterotoxin interacts with claudins via electrostatic attraction

Area of Science:

• Molecular Biology
• Cell Biology
• Toxicology

Background:

• Clostridium perfringens enterotoxin (CPE) causes food poisoning by forming pores in cell membranes.
• Claudins, proteins in tight junctions, act as cell surface receptors for CPE.
• The specific mechanism of CPE's selective binding to certain claudins is not understood.

Purpose of the Study:

• To identify the specific region of claudin responsible for CPE interaction.
• To elucidate the molecular mechanism underlying CPE's selective binding to claudins.

Main Methods:

• Localization of the CPE-binding region on claudin to the C-terminal of the second extracellular loop.
• Analysis of isoelectric points (pI) of this region in sensitive and insensitive claudins.
• Amino acid substitution experiments to alter claudin sensitivity to CPE.
• Analysis of the steric structure of the CPE-binding domain.

Main Results:

• The CPE-binding region on claudin was identified in the second extracellular loop.
• Sensitive claudins possess a higher pI in this region compared to insensitive claudins.
• Altering the pI of this region modified claudin sensitivity to CPE.
• CPE features an acidic cleft crucial for binding to basic regions on sensitive claudins.

Conclusions:

• The interaction between CPE and claudin is mediated by electrostatic attraction.
• A basic region on claudin's second extracellular loop interacts with an acidic cleft on CPE.
• This charge-based interaction explains the toxin's selective binding to specific claudins.