Summary information and primary citation

PDB-id
6ifn; DSSR-derived features in text and JSON formats
Class
RNA binding protein
Method
X-ray (2.9 Å)
Summary
Crystal structure of type iii-a crispr csm complex
Reference
You L, Ma J, Wang J, Artamonova D, Wang M, Liu L, Xiang H, Severinov K, Zhang X, Wang Y (2019): "Structure Studies of the CRISPR-Csm Complex Reveal Mechanism of Co-transcriptional Interference." Cell, 176, 239-253.e16. doi: 10.1016/j.cell.2018.10.052.
Abstract
Csm, a type III-A CRISPR-Cas interference complex, is a CRISPR RNA (crRNA)-guided RNase that also possesses target RNA-dependent DNase and cyclic oligoadenylate (cOA) synthetase activities. However, the structural features allowing target RNA-binding-dependent activation of DNA cleavage and cOA generation remain unknown. Here, we report the structure of Csm in complex with crRNA together with structures of cognate or non-cognate target RNA bound Csm complexes. We show that depending on complementarity with the 5' tag of crRNA, the 3' anti-tag region of target RNA binds at two distinct sites of the Csm complex. Importantly, the interaction between the non-complementary anti-tag region of cognate target RNA and Csm1 induces a conformational change at the Csm1 subunit that allosterically activates DNA cleavage and cOA generation. Together, our structural studies provide crucial insights into the mechanistic processes required for crRNA-meditated sequence-specific RNA cleavage, RNA target-dependent non-specific DNA cleavage, and cOA generation.

Cartoon-block schematics in six views (download the tarball)

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