Crystallization and preliminary X-ray analysis of the Clostridium botulinum type D nontoxic nonhaemagglutinin.

Clostridium botulinum produces botulinum neurotoxin (BoNT) as a large toxin complex assembled with nontoxic nonhaemagglutinin (NTNHA) and/or haemagglutinin components. Complex formation with NTNHA is considered to be critical in eliciting food poisoning because the complex shields the BoNT from the harsh conditions in the digestive tract. In the present study, NTNHA was expressed in Escherichia coli and crystallized. Diffraction data were collected to 3.9 A resolution. The crystal belonged to the trigonal space group P321 or P3121/P3221, with unit-cell parameters a = b = 147.85, c = 229.74 A. The structure of NTNHA will provide insight into the assembly mechanism that produces the unique BoNT–NTNHA complex.