6O7B

Crystal structure of Csm1-Csm4 cassette in complex with cA4

Summary for 6O7B

• Entry DOI: 10.2210/pdb6o7b/pdb
• Descriptor: CRISPR system single-strand-specific deoxyribonuclease Cas10/Csm1 (subtype III-A), Csm4, Cyclic RNA cA4, ... (4 entities in total)
• Functional Keywords: type iii-a crispr-cas system, csm1-csm4 cassette in complex with ca4, immune system, immune system-dna complex, immune system-rna complex, immune system/rna
• Biological source: Thermococcus onnurineus (strain NA1); More
• Total number of polymer chains: 4
• Total formula weight: 124595.39

Authors

Jia, N.,Patel, D.J. (deposition date: 2019-03-07, release date: 2019-07-31, Last modification date: 2024-10-16)

Primary citation

Jia, N.,Jones, R.,Sukenick, G.,Patel, D.J.
Second Messenger cA4Formation within the Composite Csm1 Palm Pocket of Type III-A CRISPR-Cas Csm Complex and Its Release Path.
Mol.Cell, 75:933-943.e6, 2019

PubMed Abstract: Target RNA binding to crRNA-bound type III-A CRISPR-Cas multi-subunit Csm surveillance complexes activates cyclic-oligoadenylate (cA) formation from ATP subunits positioned within the composite pair of Palm domain pockets of the Csm1 subunit. The generated cA second messenger in turn targets the CARF domain of trans-acting RNase Csm6, triggering its HEPN domain-based RNase activity. We have undertaken cryo-EM studies on multi-subunit Thermococcus onnurineus Csm effector ternary complexes, as well as X-ray studies on Csm1-Csm4 cassette, both bound to substrate (AMPPNP), intermediates (pppA), and products (cA), to decipher mechanistic aspects of cA formation and release. A network of intermolecular hydrogen bond alignments accounts for the observed adenosine specificity, with ligand positioning dictating formation of linear pppA intermediates and subsequent cA formation by cyclization. We combine our structural results with published functional studies to highlight mechanistic insights into the role of the Csm effector complex in mediating the cA signaling pathway.

PubMed: 31326272
DOI: 10.1016/j.molcel.2019.06.013

Experimental method

X-RAY DIFFRACTION (2.4 Å)