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Publication Abstract from PubMed

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.

Structural basis of negative regulation of CRISPR-Cas7-11 by TPR-CHAT.,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 Signal Transduct Target Ther. 2024 May 13;9(1):111. doi: , 10.1038/s41392-024-01821-4. PMID:38735995^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.