cyclic oligonucleotide-based anti-phage signaling system-associated NucC nuclease and similar proteins
Cyclic oligonucleotide-based anti-phage signaling system (CBASS)-associated NucC nuclease kills phage-infected cells through genome destruction. It is allosterically activated by a cyclic triadenylate (cA3) second messenger that is synthesized by CBASS upon infection. NucC is related to restriction endonucleases but it adopts a homotrimeric structure. Binding of cA3 causes two NucC homotrimers to assemble into a homohexamer, which brings together a pair of active sites to activate DNA cleavage. NucC has also been integrated into type III CRISPR/Cas systems as an accessory nuclease.
Feature 1:putative cAAA binding site [chemical binding site]
Evidence:
Comment:Binding of cAAA (or cA3) causes two NucC homotrimers to assemble into a homohexamer, and the activation of the enzyme. There are two cAAA binding sites in the homohexamer.
Structure:6Q1H: Pseudomonas aeruginosa NucC with bound cAAA; contacts at 4A - View structure with Cn3D
Structure:6P7P: Escherichia coli MS 115-1 NucC with bound cyclic tri-AMP (5'-3' linked); contacts at 4A - View structure with Cn3D
Lu S et al.(2020). "CDD/SPARCLE: the conserved domain database in 2020.",