Structural insights into the regulation of Cas7-11 by TPR-CHAT

Babatunde Ekundayo; Davide Torre; Bertrand Beckert; Sergey Nazarov; Alexander Myasnikov; Henning Stahlberg; Dongchun Ni

doi:10.1038/s41594-022-00894-5

Structural insights into the regulation of Cas7-11 by TPR-CHAT

Nat Struct Mol Biol. 2023 Feb;30(2):135-139. doi: 10.1038/s41594-022-00894-5. Epub 2022 Dec 5.

Authors

Babatunde Ekundayo¹, Davide Torre¹, Bertrand Beckert², Sergey Nazarov², Alexander Myasnikov², Henning Stahlberg³, Dongchun Ni⁴

Affiliations

¹ Laboratory of Biological Electron Microscopy, Institute of Physics, School of Basic Sciences, EPFL, and Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland.
² Dubochet Center for Imaging, EPFL, University of Lausanne and University of Geneva, Lausanne, Switzerland.
³ Laboratory of Biological Electron Microscopy, Institute of Physics, School of Basic Sciences, EPFL, and Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland. henning.stahlberg@epfl.ch.
⁴ Laboratory of Biological Electron Microscopy, Institute of Physics, School of Basic Sciences, EPFL, and Department of Fundamental Microbiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland. dongchun.ni@epfl.ch.

Abstract

The CRISPR-guided caspase (Craspase) complex is an assembly of the target-specific RNA nuclease known as Cas7-11 bound to CRISPR RNA (crRNA) and an ancillary protein known as TPR-CHAT (tetratricopeptide repeats (TPR) fused with a CHAT domain). The Craspase complex holds promise as a tool for gene therapy and biomedical research, but its regulation is poorly understood. TPR-CHAT regulates Cas7-11 nuclease activity via an unknown mechanism. In the present study, we use cryoelectron microscopy to determine structures of the Desulfonema magnum (Dm) Craspase complex to gain mechanistic insights into its regulation. We show that DmTPR-CHAT stabilizes crRNA-bound DmCas7-11 in a closed conformation via a network of interactions mediated by the DmTPR-CHAT N-terminal domain, the DmCas7-11 insertion finger and Cas11-like domain, resulting in reduced target RNA accessibility and cleavage.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

CRISPR-Associated Proteins* / metabolism
CRISPR-Cas Systems / genetics
Cryoelectron Microscopy
Nucleic Acid Conformation
Protein Conformation
RNA, Bacterial / chemistry
Tetratricopeptide Repeat*

Substances

RNA, Bacterial
CRISPR-Associated Proteins