Crystallization and preliminary X-ray diffraction analysis of human IL-22 bound to the extracellular IL-22R1 chain

Interleukin-22 (IL-22) is a potent mediator of cellular inflammatory responses. Crystals of IL-22 bound to the extracellular high-affinity cell-surface receptor sIL-22R1 have been grown from polyethylene glycol solutions. Crystals suitable for X-ray diffraction analysis were only obtained with mutants of IL-22 and sIL-22R1 that removed the N-linked glycosylation sites found in the wild-type amino-acid sequences. The crystals belonged to space group P2(1), with unit-cell parameters a = 50.43, b = 76.33, c = 114.92 A, beta = 92.45 degrees , and diffracted X-rays to 3.2 A resolution. The crystallographic asymmetric unit contained two IL-22-sIL-22R1 complexes, corresponding to a solvent content of approximately 52%.