Crystallization of DsbC, the disulfide bond isomerase of Escherichia coli

Abstract

DsbC is a 2 x 23 kDa soluble dimeric protein molecule involved in protein disulfide bond formation in the E. coli periplasm, primarily catalyzing disulfide bond rearrangements. Crystals of both the native and selenomethione protein suitable for structure determination were obtained using the hanging-drop vapour-diffusion method. The best crystals were obtained using 18-22% (v/v) polyethylene glycol 550 monomethyl ether in 100 mM Tris-HCl (pH 8.9). Seeding methods were used to produce large crystals diffracting to 2 A resolution, and the detergent n-octyl-beta-glucoside was used to improve crystal quality. Significant variation in cell dimensions and crystal order was observed. Cell dimensions obtained for frozen crystals were in the range a = 58.8 (0.3), b = 78.9 (0.5), c = 95.2 (5.0) A. The lattice is orthorhombic and systematic absences indicate that the space group is P2(1)2(1)2(1)