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Title | Second Messenger cA Formation within the Composite Csm1 Palm Pocket of Type III-A CRISPR-Cas Csm Complex and Its Release Path. |
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Journal, issue, pages | Mol Cell, Vol. 75, Issue 5, Page 933-943.e6, Year 2019 |
Publish date | Sep 5, 2019 |
Authors | Ning Jia / Roger Jones / George Sukenick / Dinshaw J Patel / |
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 ...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. |
External links | Mol Cell / PubMed:31326272 / PubMed Central |
Methods | EM (single particle) / X-ray diffraction |
Resolution | 2.4 - 3.2 Å |
Structure data | EMDB-0640, PDB-6o7e: EMDB-0641, PDB-6o7h: EMDB-0642, PDB-6o7i: PDB-6o73: PDB-6o74: PDB-6o75: PDB-6o78: PDB-6o79: PDB-6o7b: PDB-6o7d: |
Chemicals | ChemComp-NI: ChemComp-ANP: ChemComp-MN: ChemComp-HOH: ChemComp-ATP: ChemComp-ZN: ChemComp-5GP: |
Source |
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Keywords | IMMUNE SYSTEM / Type III-A CRISPR-Cas system / apo Csm1-Csm4 cassette / aCsm1-Csm4 cassette in complex with AMPPNP / immune system/rna / Csm1-Csm4 cassette in complex with pppApA / immune system-dna complex / immune system-rna complex / Csm1-Csm4 cassette in complex with pppApApA / immune sytem/rna / Csm1-Csm4 cassette in complex with cA3 / immune sytem-rna complex / Csm1-Csm4 cassette in complex with cA4 / Csm1-Csm4 cassette in complex with one ATP / cryo-EM structure / Csm-crRNA-target RNA ternary complex in complex with AMPPNP / Type III CRISPR-Cas systerm / immune system/rna/dna / Csm-crRNA-target RNA ternary complex in complex with CA4 / immune system-rna-dna complex / Csm-crRNA-target RNA ternary bigger complex in complex with CA4 |