By combining cryo-electron microscopy, AlphaFold 2 predictions, molecular dynamics simulations and various biochemical assays, Grabarczyk et al. revealed that RNA-induced dimerization activates ZNFX1. They found that ZNFX1 can ubiquitinate RNA at the ribose 2′OH to form ribonucleoprotein condensates. The team also showed that ZNFX1 can be activated by single-stranded RNA or DNA (ssRNA or ssDNA) in a length-dependent manner. The translocase activity of the helicase module drives the unidirectional movement of ZNFX1 along an ssRNA molecule. When the ssRNA molecule is long enough to form loops, two ZNFX1 molecules on it can run into each other and form a homodimer, activating ZNFX1 by bringing the E2-binding ZF12 on one ZNFX1 monomer into proximity with the RZ domain on the other monomer. Cellular assays show that the RNA-ubiquitination activity is essential for the protective role of ZNFX1 during interferon signaling. Overall, this study provides a framework for understanding the activation mechanism of ZNFX1 and its role in viral infections.
Original reference: Cell https://doi.org/10.1016/j.cell.2025.08.006 (2025)
