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-affinity receptor (sIL-10R1) has been crystallized from polyethylene glycol solutions. Crystals suitable for diffraction analysis required the modification of the NXS/T glycosylation sites on sIL-­10R1 by site-directed mutagenesis and inclusion of the detergent cyclohexyl-methyl-β-D-maltopyranoside in the crystallization experiments. The crystals belong to space group P3₂12 or its enantimorph P3₁12, with unit-cell parameters a = b = 46.23, c = 307.78 Å, α = β = 90, γ = 120°, and diffract X-rays to ∼2.9 Å. The IL-10 dimer is positioned on a crystallographic twofold, resulting in one IL-10 chain and one sIL-10R1 chain in the asymmetric unit, which corresponds to a solvent content of approximately 44%.