ZNFX1 is a highly conserved, interferon-induced RNA helicase (1,913 amino acids) implicated in antiviral defence, inflammation control, and RNA regulation. Biallelic mutations in ZNFX1 cause immunodeficiency-91, a monogenic disorder marked by recurrent infections, systemic inflammation, and organ dysfunction. ZNFX1 contains a DExH-box helicase core and a zinc finger domain, as well as a large C-terminal region of unknown function. This suggests that it has modular roles in RNA binding, unwinding and protein interactions.

Although ZNFX1 binds double-stranded RNA and activates MAVS-dependent signalling, its structural organisation and molecular interactions remain poorly defined. We propose to characterise the architecture of human ZNFX1 using cross-linking mass spectrometry (XL-MS) and complementary proteomics.

By integrating structural modelling with advanced cross-linking techniques, we aim to identify interdomain contacts and RNA-protein interaction surfaces. Based on parallels with other RNA helicases, we expect to identify autoinhibitory domains that may regulate ZNFX1 activation.

These insights could inform future strategies to harness or dampen innate immune responses. Our data will also support the interpretation of 20 patient-derived ZNFX1 variants associated with immunodeficiency-like phenotypes, shared by our clinical collaborator