Download MendeleySequential structural rearrangements at the PAM-distal site of a type I-F3 CRISPR-Cas effector enabling RNA-guided DNA transposition.
Ishihara, K., Matsumoto, S., Gerle, C., Gopalasingam, C.C., Shigematsu, H., Shirai, T., Numata, T.(2026) Nucleic Acids Res 54
- PubMed: 41495894
- DOI: https://doi.org/10.1093/nar/gkaf1415
- Primary Citation of Related Structures:
9VTP, 9VTQ, 9VTR - PubMed Abstract:
Some prokaryotes carry CRISPR-associated transposons (CASTs), Tn7-like elements that incorporate genes encoding CRISPR-Cas effectors. CAST insertion is directed by CRISPR-Cas effectors through RNA-guided DNA binding and interactions with transposition-associated proteins. Although efficient sequence-specific DNA integration requires both precise target DNA recognition and coordinated interactions between effectors and transposition-associated proteins, the underlying mechanism remains elusive. Here, we determined three cryo-EM structures of target DNA-bound type I-F3 TniQ-Cascade from Vibrio parahaemolyticus, revealing how Cas8/5 recognizes the protospacer adjacent motif (PAM) and identifying a key residue responsible for the cytidine preference at position -2 of the PAM. We revealed mismatch tolerance at the PAM-proximal site. Structural analyses showed that correct base pairing at the PAM-distal site correlates with conformational changes in the Cas8/5 helical bundle and TniQ, bending the DNA to guide its downstream region toward the transposition machinery. Together, these dynamic rearrangements at the PAM-distal region provide insights into the licensing mechanism of type I-F3 CAST transposition and highlight its potential for genome engineering applications.
- Department of Bioscience and Biotechnology, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 819-0395, Japan.
Organizational Affiliation:
