7YGH

Crystal Structure of the ring nuclease Sso2081 from Saccharolobus solfataricus in complex with cyclic-tetraadenylate (cA4)

Summary for 7YGH

• Entry DOI: 10.2210/pdb7ygh/pdb
• Descriptor: CRISPR system ring nuclease SSO2081, RNA (5'-R(P*AP*AP*AP*A)-3') (3 entities in total)
• Functional Keywords: sso2081, ring nuclease, cyclic-tetraadenylates(ca4), protein-ca4 complex, hydrolase
• Biological source: Saccharolobus solfataricus P2; More
• Total number of polymer chains: 3
• Total formula weight: 42896.13

Authors

Lin, Z.,Du, L.,Luo, Z. (deposition date: 2022-07-11, release date: 2023-02-15, Last modification date: 2024-11-20)

Primary citation

Du, L.,Zhang, D.,Luo, Z.,Lin, Z.
Molecular basis of stepwise cyclic tetra-adenylate cleavage by the type III CRISPR ring nuclease Crn1/Sso2081.
Nucleic Acids Res., 51:2485-2495, 2023

PubMed Abstract: The cyclic oligoadenylates (cOAs) act as second messengers of the type III CRISPR immunity system through activating the auxiliary nucleases for indiscriminate RNA degradation. The cOA-degrading nucleases (ring nucleases) provide an 'off-switch' regulation of the signaling, thereby preventing cell dormancy or cell death. Here, we describe the crystal structures of the founding member of CRISPR-associated ring nuclease 1 (Crn1) Sso2081 from Saccharolobus solfataricus, alone, bound to phosphate ions or cA4 in both pre-cleavage and cleavage intermediate states. These structures together with biochemical characterizations establish the molecular basis of cA4 recognition and catalysis by Sso2081. The conformational changes in the C-terminal helical insert upon the binding of phosphate ions or cA4 reveal a gate-locking mechanism for ligand binding. The critical residues and motifs identified in this study provide a new insight to distinguish between cOA-degrading and -nondegrading CARF domain-containing proteins.

PubMed: 36807980
DOI: 10.1093/nar/gkad101

Experimental method

X-RAY DIFFRACTION (3.11 Å)