FIG. 1.

Structure-function properties of the BoNT. Ribbon (A) and line (B) diagrams of BoNT/A (Protein Data Bank entry no. 3BTA) are shown. BoNTs are organized into three domains: the N terminus, LC, encodes a zinc protease (red), and the C terminus, HC, encodes an HCT (yellow) and an HCR (blue). (C) Purification of HCR/A to HCR/G. Individual plasmids encoding HCR (serotypes A to G) were expressed as six-His-tag fusion proteins in E. coli. Proteins were purified by affinity- and size-exclusion chromatography. Five micrograms of each HCR was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The gel was stained with Coomassie blue and is shown. To the left are the migrations of three molecular size markers (kDa).