Evidence for a modular structure of the homologous repetitive C-terminal carbohydrate-binding sites of Clostridium difficile toxins and Streptococcus mutans glucosyltransferases

The homologous C-terminal repeats of Clostridium difficile toxins and streptococcal glucosyltransferases appear to be involved in carbohydrate-protein interaction. A consensus sequence of 134 repeating units derived from gram-positive bacteria indicates that these repeats have a modular design. It was proposed that the highly homologous sequences act as the initial attachment sites for carbohydrates and mediate a nonspecific carbohydrate interaction with the proteins.