EMD-33439
Structure of Craspase-NTR
EMD-33439
Single-particle3.08 Å
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Map released: 09/11/2022
Last modified: 03/07/2024
Sample Organism:
Candidatus Scalindua brodae
Sample: Craspase-NTR complex
Fitted models: 7xt4 (Avg. Q-score: 0.536)
Deposition Authors: Feng Y
,
Zhang L
Sample: Craspase-NTR complex
Fitted models: 7xt4 (Avg. Q-score: 0.536)
Deposition Authors: Feng Y
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Target RNA activates the protease activity of Craspase to confer antiviral defense.
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) Mol Cell , 82 , 4503 - 4518.e8
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(2022) Mol Cell , 82 , 4503 - 4518.e8
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.
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.