Structural insights into distinct filamentation states reveal a regulatory mechanism for bacterial STING activation.

ABSTRACT: The cyclic oligonucleotide-based antiphage signaling system (CBASS) is a bacterial immune mechanism that was evolutionarily linked to the eukaryotic cGAS-STING pathway, which protects against phage infection through abortive cell death. CBASS operons encode cyclic dinucleotide synthases (CD-NTases) and effector proteins (Caps), such as bacterial STING, which senses cyclic dinucleotides like 3'3'-c-di-GMP to trigger defense. Although bacterial STING oligomerizes into filaments upon ligand binding, the functional roles of distinct filament states remain unclear. Here, we resolve cryo-EM structures of Epilithonimonas lactis TIR-STING (ElSTING) bound to 3'3'-c-di-GMP, revealing two oligomeric states: spiral-shaped single filaments and fiber bundles composed of straight protofibri

SUBMITTER: Yang Y 

PROVIDER: S-EPMC12421889 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature