The CorA-associated type III-B CRISPR–Cas system synthesizes S-adenosyl methionine (SAM)-AMP, triggering immune responses. Through structural characterization and biochemical validation, Duan and Jin et al. unveil unique mechanisms for SAM-AMP synthesis and degradation and provide insights into the molecular basis of type III CRISPR–Cas signaling.
- Benzhen Duan
- Xiaohui Jin
- Baoyu Zhao