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Title | Target RNA activates the protease activity of Craspase to confer antiviral defense. |
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Journal, issue, pages | Mol Cell, Vol. 82, Issue 23, Page 4503-44518.e8, Year 2022 |
Publish date | Dec 1, 2022 |
Authors | Xi Liu / Laixing Zhang / Hao Wang / Yu Xiu / Ling Huang / Zhengyu Gao / Ningning Li / Feixue Li / Weijia Xiong / Teng Gao / Yi Zhang / Maojun Yang / Yue Feng / |
PubMed 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 ...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. |
External links | Mol Cell / PubMed:36306795 |
Methods | EM (single particle) |
Resolution | 2.88 - 3.2 Å |
Structure data | EMDB-33429, PDB-7xso: EMDB-33430, PDB-7xsp: EMDB-33431, PDB-7xsq: EMDB-33432, PDB-7xsr: EMDB-33433, PDB-7xss: EMDB-33439, PDB-7xt4: |
Chemicals | ChemComp-ZN: |
Source |
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Keywords | IMMUNE SYSTEM/RNA / IMMUNE SYSTEM-RNA complex |