Crystallization and preliminary crystallographic studies of human RIG-I in complex with double-stranded RNA.

Retinoic acid inducible gene-I (RIG-I) is an essential component of the innate immune system that is responsible for the detection and elimination of invading viruses. RIG-I recognizes viral RNAs inside the cell and then initiates downstream signalling to activate the IRF-3 and NF-kappaB genes, which results in the production of type I interferons. RIG-I is composed of an N-terminal CARD domain for signalling and C-terminal helicase and repressor domains for RNA recognition. A RIG-I-RNA binding assay was performed to investigate the in vitro RIG-I-RNA binding properties. Selenomethionine-incorporated RIG-I was expressed using Escherichia coli and purified for crystallization. X-ray data were collected from RIG-I-dsRNA complex crystals to 2.8 A resolution using synchrotron radiation.