Crystallization and biochemical studies of the NYN domain of human KHNYN

KHNYN is composed of an N-terminal KH-like RNA-binding domain and a C-terminal PIN/NYN endoribonuclease domain. It forms a complex with zinc-finger antiviral protein (ZAP), leading to the degradation of viral or cellular RNAs depending on the ZAP isoform. Here, the production, crystallization and biochemical analysis of the NYN domain (residues 477-636) of human KHNYN are presented. The NYN domain was crystallized with a heptameric single-stranded RNA from the AU-rich elements of the 3'-UTR of interferon lambda 3. The crystal belonged to space group P4₁32, with unit-cell parameters a = b = c = 111.3 Å, and diffacted to 1.72 Å resolution. The RNase activity of the NYN domain was demonstrated using different single-stranded RNAs, together with the binding between the NYN domain of KHNYN and the zinc-finger domain of ZAP.