Crystallization of the B chain of Shiga-like toxin I from Escherichia coli

Shiga-like toxin I (SLT-I) is produced by several pathogenic strains of Escherichia coli associated with diarrheal disease. The toxin consists of an A chain, which attacks eukaryotic ribosomes, inhibiting protein synthesis, and multiple copies of a 69 amino acid B chain. The B subunit mediates cell binding and uptake through its interactions with cell surface carbohydrate moieties. Here we report that the B chain has been crystallized in a form suitable for high-resolution X-ray analysis. The space group is P2(1)2(1)2(1), with a = 56.2 A, b = 59.9 A and c = 102.5 A. A rotation function using three-dimensional diffraction data suggests that the asymmetric unit is a tetramer.