Structural highlights
FunctionPublication Abstract from PubMedSome 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. Sequential 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 CC, Shigematsu H, Shirai T, Numata T Nucleic Acids Res. 2026 Jan 5;54(1):gkaf1415. doi: 10.1093/nar/gkaf1415. PMID:41495894[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
| ||||||||||||||||||||
This page was last modified 07:31, 11 February 2026.