Overexpression, purification, crystallization and preliminary X‐ray studies of Vibrio cholerae EpsG

EpsG is the major pseudopilin protein of the Vibrio cholerae type II secretion system. An expression plasmid that encodes an N‐terminally truncated form of EpsG with a C‐terminal noncleavable His tag was constructed. Recombinant EpsG was expressed in Escherichia coli ; the truncated protein was purified and crystallized by hanging‐drop vapor diffusion against a reservoir containing 6 m M zinc sulfate, 60 m M MES pH 6.5, 15% PEG MME 550. The crystals diffracted X‐rays to a resolution of 2.26 Å and belonged to space group P 2 1 , with unit‐cell parameters a = 88.61, b = 70.02, c = 131.54 Å.