8FD2

Cryo-EM structure of Cascade complex in type I-B CAST system

Summary for 8FD2

• Entry DOI: 10.2210/pdb8fd2/pdb
• EMDB information: 29000
• Descriptor: A Type I-B CRISPR-associated protein Cas5, Type I-B CRISPR-associated protein Cas6, Type I-B CRISPR-associated protein Cas7, ... (6 entities in total)
• Functional Keywords: cascade, i-b, cast, dna binding protein
• Biological source: Nostoc sp. 'Peltigera membranacea cyanobiont' 210A; More
• Total number of polymer chains: 13
• Total formula weight: 408886.58

Authors

Chang, L.,Wang, S. (deposition date: 2022-12-01, release date: 2023-08-09, Last modification date: 2025-06-04)

Primary citation

Wang, S.,Gabel, C.,Siddique, R.,Klose, T.,Chang, L.
Molecular mechanism for Tn7-like transposon recruitment by a type I-B CRISPR effector.
Cell, 186:4204-4215.e19, 2023

PubMed 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.

PubMed: 37557170
DOI: 10.1016/j.cell.2023.07.010

Experimental method

ELECTRON MICROSCOPY (3.65 Å)