Summary information and primary citation
- PDB-id
-
7xt4;
DSSR-derived features in text and
JSON formats
- Class
- immune system-RNA
- Method
- cryo-EM (3.08 Å)
- Summary
- Structure of craspase-ntr
- Reference
-
Liu X, Zhang L, Wang H, Xiu Y, Huang L, Gao Z, Li N, Li
F, Xiong W, Gao T, Zhang Y, Yang M, Feng Y (2022):
"Target RNA
activates the protease activity of Craspase to confer
antiviral defense." Mol.Cell,
82, 4503-4518.e8. doi: 10.1016/j.molcel.2022.10.007.
- Abstract
- In the type III-E CRISPR-Cas system, a Cas effector
(gRAMP) is associated with a TPR-CHAT to form Craspase
(CRISPR-guided caspase). However, both the structural
features of gRAMP and the immunity mechanism remain unknown
for this system. Here, we report structures of gRAMP-crRNA
and gRAMP:cRNA:target RNA as well as structures of Craspase
and Craspase complexed with cognate target RNA (CTR) or
non-cognate target RNA (NTR). Importantly, the 3' anti-tag
region of NTR and CTR binds at two distinct channels in
Craspase, and CTR with a non-complementary 3' anti-tag
induces a marked conformational change of the TPR-CHAT,
which allosterically activates its protease activity to
cleave an ancillary protein Csx30. This cleavage then
triggers an abortive infection as the antiviral strategy of
the type III-E system. Together, our study provides crucial
insights into both the catalytic mechanism of the gRAMP and
the immunity mechanism of the type III-E system.
