The mutational landscape of STING-induced immunity

Stimulator of interferon genes (STING) is an evolutionary conserved immune signalling protein with key roles in host defence, cancer, senescence and inflammation.STING activation leads to type I interferon (IFN), NF-κB pathway and non-canonical autophagy responses. Despite its central role in immunity and relevance as therapeutic target, the sequence elements that govern STING (in)activation in cells remain poorly understood. Here we developed a massively parallel assay to systematically chart the sequence-function landscape of STING. Profiling thousands of single amino-acid variants, we reconstructed structural and functional determinants that moderate or enable, respectively, STING’s immunostimulatory capacity and its ability to translate ligand recognition into cellular effector responses. Cryo-electron microscopy structures of distinct STING hyperactive variants revealed novel regulatory principles dictating conformational transition from inactive to signalling-competent states of STING. Collectively, these findings define the molecular principles that tune STING activity and chart the full landscape of its functional potential across immune contexts.