Refolding, Characterization, and Preliminary X-ray Crystallographic Studies on the Campylobacter concisus Plasmid-Encoded Secreted Protein Csep1 p Associated with Crohn’s Disease

摘要

Colonization of Campylobacter concisus in the gastrointestinal tract can lead to the development of inflammatory bowel disease (IBD). Plasmid-encoded C. concisus -secreted protein 1 (Csep1 p ) was recently identified as a putative pathogenicity marker associated with active Crohn’s disease, a clinical form of IBD. Csep1 p shows no significant full-length sequence similarity to proteins of known structure, and its role in pathogenesis is not yet known. This study reports a method for extraction of recombinantly expressed Csep1 p from Escherichia coli inclusion bodies, refolding, and purification to produce crystallizable protein. Purified recombinant Csep1 p behaved as a monomer in solution. Crystals of Csep1 p were grown by the hanging drop vapour diffusion method, using polyethylene glycol (PEG) 4000 as the precipitating agent. A complete data set has been collected to 1.4 ? resolution, using cryocooling conditions and synchrotron radiation. The crystals belong to space group P 6 2 or P 6 4 , with unit cell parameters a = b = 85.8, c = 55.2 ?, α = β = 90, and γ = 120°. The asymmetric unit appears to contain one subunit, corresponding to a packing density of 2.47 ? 3 Da ?1 .