The CRISPR effector Cam1 mediates membrane depolarization for phage defence

• 成果类型: Article
• 署名作者: Baca, Christian F.; Yu, You; Rostol, Jakob T.; Majumder, Puja; Patel, Dinshaw J.; Marraffini, Luciano A.
• 署名单位: Rockefeller University; Cornell University; Weill Cornell Medicine; Rockefeller University; Memorial Sloan Kettering Cancer Center; Memorial Sloan Kettering Cancer Center; Rockefeller University; Howard Hughes Medical Institute; Imperial College London
• 刊物名称: Nature
• ISSN/ISSBN: 0028-6642
• DOI: 10.1038/s41586-023-06902-y
• 发表日期: 2024-01-25
• 关键词: horizontal transfer; rna cleavage; cas systems; dna; repeats; sequence; stoichiometry; bacteriophage; degradation; TOPOLOGY

摘要

Prokaryotic type III CRISPR-Cas systems provide immunity against viruses and plasmids using CRISPR-associated Rossman fold (CARF) protein effectors1-5. Recognition of transcripts of these invaders with sequences that are complementary to CRISPR RNA guides leads to the production of cyclic oligoadenylate second messengers, which bind CARF domains and trigger the activity of an effector domain6,7. Whereas most effectors degrade host and invader nucleic acids, some are predicted to contain transmembrane helices without an enzymatic function. Whether and how these CARF-transmembrane helix fusion proteins facilitate the type III CRISPR-Cas immune response remains unknown. Here we investigate the role of cyclic oligoadenylate-activated membrane protein 1 (Cam1) during type III CRISPR immunity. Structural and biochemical analyses reveal that the CARF domains of a Cam1 dimer bind cyclic tetra-adenylate second messengers. In vivo, Cam1 localizes to the membrane, is predicted to form a tetrameric transmembrane pore, and provides defence against viral infection through the induction of membrane depolarization and growth arrest. These results reveal that CRISPR immunity does not always operate through the degradation of nucleic acids, but is instead mediated via a wider range of cellular responses. The prokaryotic non-enzymatic effector protein Cam1 mediates CRISPR immunity by binding tetra-adenylate second messengers and forming a pore in the membrane that induces membrane depolarization and growth arrest.