Crystallization and preliminary X-ray diffraction studies of the water-soluble state of the pore-forming toxin sticholysin II from the sea anemone Stichodactyla helianthus

Sticholysin II (StnII) is a potent cytolytic protein produced by the sea anemone Stichodactyla helianthus. StnII belongs to the actinoporin family, a group of proteins which are characterized by their ability to spontaneously interact with biological membranes. The cytolytic character of these proteins is currently explained in terms of a molecular mechanism involving the formation of transmembrane pores. StnII has been crystallized using the hanging-drop vapour-diffusion method at 291 K. Diffraction-quality crystals have unit-cell parameters a = 32.30, b = 119.73, c = 43.42 Å, β = 90.04° and belong to the monoclinic space group P2₁. Diffraction data to a resolution of 1.71 Å were collected at synchrotron facilities.