Crystallization and preliminary crystallographic studies of the HA3 subcomponent of the type B botulinum neurotoxin complex

The haemagglutinin subcomponent HA3 of the type B botulinum neurotoxin complex, which is important in toxin absorption from the gastrointestinal tract, has been expressed, purified and subsequently crystallized in two crystal forms at different pH values. Form I belonged to space group R32, with unit-cell parameters a = b = 357.4, c = 249.5 Å, α = β = 90, γ = 120°. Form II belonged to space group I4₁32, with unit-cell parameters a = b = c = 259.0 Å, α = β = γ = 90°. Diffraction data were collected from these crystals to a resolution of 3.0 Å for both form I and form II.