SNAP output for PDB entry 8wmc [SNAP web server]

PDB-id

8wmc; SNAP-derived features in text and JSON formats; DNAproDB

Class

immune system

Method

cryo-EM (2.9 Å)

Summary

cryo-EM structure of dicas7-11-crrna in complex with regulator

Reference

Hong T, Luo Q, Ma H, Wang X, Li X, Shen C, Pang J, Wang Y, Chen Y, Zhang C, Su Z, Dong H, Tang X (2024): "Structural basis of negative regulation of CRISPR-Cas7-11 by TPR-CHAT." Signal Transduct Target Ther, 9, 111. doi: 10.1038/s41392-024-01821-4.

Abstract

CRISPR‒Cas7-11 is a Type III-E CRISPR-associated nuclease that functions as a potent RNA editing tool. Tetratrico-peptide repeat fused with Cas/HEF1-associated signal transducer (TPR-CHAT) acts as a regulatory protein that interacts with CRISPR RNA (crRNA)-bound Cas7-11 to form a CRISPR-guided caspase complex (Craspase). However, the precise modulation of Cas7-11's nuclease activity by TPR-CHAT to enhance its utility requires further study. Here, we report cryo-electron microscopy (cryo-EM) structures of Desulfonema ishimotonii (Di) Cas7-11-crRNA, complexed with or without the full length or the N-terminus of TPR-CHAT. These structures unveil the molecular features of the Craspase complex. Structural analysis, combined with in vitro nuclease assay and electrophoretic mobility shift assay, reveals that DiTPR-CHAT negatively regulates the activity of DiCas7-11 by preventing target RNA from binding through the N-terminal 65 amino acids of DiTPR-CHAT (DiTPR-CHAT_NTD). Our work demonstrates that DiTPR-CHAT_NTD can function as a small unit of DiCas7-11 regulator, potentially enabling safe applications to prevent overcutting and off-target effects of the CRISPR‒Cas7-11 system.