Fig. 3: Bacterial STING and human STING share an ancient mechanism of filament formation.
From: Cryo-EM structure of an active bacterial TIR–STING filament complex
a, The tetramer interfaces formed between the filaments within the CBD are similar for SfSTING and human STING. The ‘tetramer’ modelled here for human STING (blue, PDB 6NT5) is based on cryo-EM observation for chicken STING (PDB 6NT8). The dashed squares indicate cross-filament contact surfaces. b–d, Close-up views of SfSTING cross-filament interfaces including electrostatic contacts coordinating STING-to-STING (b), STING-to-TIR (c) and TIR-to-TIR (d) interactions. In TIR-to-TIR contacts, the BB loop and the DD loop of opposing TIR monomers reside flush against each other with only one direct contact from T115 on the DD loop to the backbone amide bond of N40 on the BB loop. Schematic depictions of cross-filament domain contacts (indicated by arrows) are shown in the upper-left insets of b–d.
