a, Ribbon representation of the structure of human TBK1 bound to the human STING CTD EMW mutant (residue 155–379, T376E, F378M and S379W). The kinase domains (KD) are in yellow and cyan, the ubiquitin-like domains (ULD) are in pink and red, the scaffold and dimerization domains (SDD) are in green and slate. The STING CTDs are shown by the blue and magenta ball-and-stick models. The TBK1 inhibitor BX795 is shown by the orange stick models. b, SDS–PAGE analysis of crystals of human TBK1 in complex with the human STING CTD EMW mutant. The data are representative of two independent experiments. c, Difference map of human STING CTT bound to mouse TBK1 contoured at 2.5σ. The σ A -weighted F o − F c map was calculated with the STING CTT omitted from the model. The CTT of STING is shown by the slate ball-and-stick model. TBK1 dimer is shown by the ribbon representation coloured in green and cyan. d, Difference map of human STING CTD bound to human TBK1 contoured at 2.5σ. The σ A -weighted F o − F c map was calculated with STING CTD omitted from the model. The CTT of STING is shown by the purple stick model. The TBK1 dimer is shown by the ribbons coloured green and cyan. e, Anomalous difference maps of Se-Met derivative of the human STING CTT EMW mutant bound to human TBK1. The blue map was calculated with model phases (ϕ c ) and the magenta map was calculated with experimental phases after density modification (ϕ dm ). The STING peptide is shown by the magenta ribbon and TBK1 shown by the green and cyan ribbons. f, Superposition of the structures of the human STING CTD EMW mutant (magenta) and human STING CTT (yellow) bound to human and mouse TBK1. Mouse TBK1 is shown by the green and cyan cartoon representation. Residues Glu376, Met378 and Trp379 from the STING CTD EMW mutant are shown by the magenta ball-and-stick models. Residues Thr376, Phe378 and Ser379 from the STING CTT are shown as the yellow ball-and-stick models.