Purification, crystallization and preliminary X-ray diffraction of a complex between IL-10 and soluble IL-10R1

A complex between interleukin-10 and the extracellular domain of its high-a ffinity receptor (sIL-10R1) has been crystallized from polyethylene glycol solutions. Crystals suitable for diffraction analysis required the modifica tion of the NXS/T glycosylation sites on sIL-10R1 by site-directed mutagene sis and inclusion of the detergent cyclohexyl-methyl-beta -D-maltopyranosid e in the crystallization experiments. The crystals belong to space group P3 (2)12 or its enantimorph P3(1)12, with unit-cell parameters a=b=46.23, c=30 7.78 Angstrom, alpha=beta =90, gamma =120 degrees, and diffract X-rays to s imilar to2.9 Angstrom. The IL-10 dimer is positioned on a crystallographic twofold, resulting in one IL-10 chain and one sIL-10R1 chain in the asymmet ric unit, which corresponds to a solvent content of approximately 44%.