Purification, crystallization and preliminary X-ray analysis of a thermostable direct haemolysin from Grimontia hollisae

Vibrio hollisae, a halophilic species recently reclassified as Grimontia hollisae, is a causative agent of gastroenteritis and septicaemia. One important pathogenic Vibrio factor, thermostable direct haemolysin (TDH), has been purified and crystallized in two crystal forms using the vapour-diffusion method. The crystals belonged to an orthorhombic space group, with unit-cell parameters a = 104.8, b = 112.4, c = 61.3 Å and a = 122.9, b = 123.3, c = 89.8 Å. The crystals contained either four or eight molecules per asymmetric unit, with predicted solvent contents of 49.4 and 46.3% and Matthews coefficients (V_M) of 2.4 and 2.3 Å³ Da^-1, respectively. These crystals were suitable for structure determination, which would yield structural details related to the cytotoxicity and oligomeric structure of this pore-forming toxin.