Retargeting Clostridium difficile Toxin B to Neuronal Cells as a Potential Vehicle for Cytosolic Delivery of Therapeutic Biomolecules to Treat Botulism

Figure 1

Engineered recombinant TcdB proteins. Native TcdB contains a glucosyltransferase domain (GT), a cysteine-protease domain (CPD), a translocation domain (TD), and a receptor-binding domain (RBD) as shown. The AGT-tag coding DNA was appended to the amino terminus in frame with the full-size TcdB coding DNA to create the AGT-TcdB expression vector. The TcdB RBD was replaced in frame with the full-size BoNT/A heavy chain carboxyl terminus (BoNT/A-Hc, amino acids 861–1296), containing the receptor-binding domain for BoNT/A, to generate AGT-TcdB-BoNT/A-Hc. The sizes of the boxes are approximately proportional to the sizes of the protein domains. Restriction sites used in preparing the constructions are indicated.