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

PDB-id

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

Class

DNA binding protein

Method

cryo-EM (2.83 Å)

Summary

cryo-EM structure of cascade-DNA (p23) complex in type i-b cast system

Reference

Wang S, Gabel C, Siddique R, Klose T, Chang L (2023): "Molecular mechanism for Tn7-like transposon recruitment by a type I-B CRISPR effector." Cell, 186, 4204-4215.e19. doi: 10.1016/j.cell.2023.07.010.

Abstract

Tn7-like transposons have co-opted CRISPR-Cas systems to facilitate the movement of their own DNA. These CRISPR-associated transposons (CASTs) are promising tools for programmable gene knockin. A key feature of CASTs is their ability to recruit Tn7-like transposons to nuclease-deficient CRISPR effectors. However, how Tn7-like transposons are recruited by diverse CRISPR effectors remains poorly understood. Here, we present the cryo-EM structure of a recruitment complex comprising the Cascade complex, TniQ, TnsC, and the target DNA in the type I-B CAST from Peltigera membranacea cyanobiont 210A. Target DNA recognition by Cascade induces conformational changes in Cas6 and primes TniQ recruitment through its C-terminal domain. The N-terminal domain of TniQ is bound to the seam region of the TnsC spiral heptamer. Our findings provide insights into the diverse mechanisms for the recruitment of Tn7-like transposons to CRISPR effectors and will aid in the development of CASTs as gene knockin tools.