Multiple enzymatic activities of a Sir2-HerA system cooperate for anti-phage defense.
Tang, D., Chen, Y., Chen, H., Jia, T., Chen, Q., Yu, Y.(2023) Mol Cell 83: 4600-4613.e6
- PubMed: 38096825 
- DOI: https://doi.org/10.1016/j.molcel.2023.11.010
- Primary Citation of Related Structures:  
8J4U - PubMed Abstract: 
In response to the persistent exposure to phage infection, bacteria have evolved diverse antiviral defense mechanisms. In this study, we report a bacterial two-component defense system consisting of a Sir2 NADase and a HerA helicase. Cryo-electron microscopy reveals that Sir2 and HerA assemble into a ∼1 MDa supramolecular octadecamer. Unexpectedly, this complex exhibits various enzymatic activities, including ATPase, NADase, helicase, and nuclease, which work together in a sophisticated manner to fulfill the antiphage function. Therefore, we name this defense system "Nezha" after a divine warrior in Chinese mythology who employs multiple weapons to defeat enemies. Our findings demonstrate that Nezha could sense phage infections, self-activate to arrest cell growth, eliminate phage genomes, and subsequently deactivate to allow for cell recovery. Collectively, Nezha represents a paradigm of sophisticated and multifaceted strategies bacteria use to defend against viral infections.
Organizational Affiliation: 
Department of Urology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610041, China.