Expression, purification, crystallization and preliminary X-ray studies of Vibrio cholerae pseudopilin EpsH.

EpsH is a minor pseudopilin protein of the Vibrio cholerae type II secretion system. A truncated form of EpsH with a C-terminal noncleavable His tag was constructed and expressed in Escherichia coli, purified and crystallized by sitting-drop vapor diffusion. A complete data set was collected to 1.71 A resolution. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 53.39, b = 71.11, c = 84.64 A. There were two protein molecules in the asymmetric unit, which gave a Matthews coefficient V(M) of 2.1 A(3) Da(-1), corresponding to 41.5% solvent content.