Preliminary X-ray study of papD crystals from uropathogenic Escherichia coli.

The product of the Escherichia coli papD gene is a periplasmic transport protein that forms complexes with pilus subunits, thereby stabilizing them as they cross the periplasmic space to the site of pilus assembly. Purified PapD protein was crystallized by the hanging drop method of vapour diffusion with polyethylene glycol 8000 as the precipitating agent at pH 6.5. The space group is P2(1)2(1)2(1), with unit cell dimensions of a = 67.0 A, b = 58.1 A and c = 64.0 A. The crystal data, together with a subunit molecular weight of 24,500 suggest that there is one monomer in the asymmetric unit. The crystals are stable in X-rays and diffract to a resolution beyond 2.0 A.