Structure-activity correlations of variant forms of the B pentamer of Escherichia coli type II heat-labile enterotoxin LT-IIb with Toll-like receptor 2 binding

Structural data for the S74D variant of the pentameric B subunit of type II heat-labile enterotoxin of Escherichia coli reveal a smaller pore opening that may explain its reduced Toll-like receptor binding affinity compared to that of the wild type enterotoxin. The explanation for the enhanced Toll-like receptor binding affinity of the S74A variant is more complex than simply being attributed to the pore opening.