8B2X

Structure of the type I-G CRISPR effector

Summary for 8B2X

• Entry DOI: 10.2210/pdb8b2x/pdb
• EMDB information: 15540 15820
• Descriptor: Type I-G CRISPR Cascade large subunit CSX17 (1 entity in total)
• Functional Keywords: crispr, effector, immune system, gene regulation
• Biological source: Thioalkalivibrio sulfidiphilus HL-EbGr7
• Total number of polymer chains: 1
• Total formula weight: 79372.02

Authors

Shangguan, Q.,Graham, S.,Sundaramoorthy, R.,White, M.F. (deposition date: 2022-09-15, release date: 2022-11-09, Last modification date: 2024-07-24)

Primary citation

Shangguan, Q.,Graham, S.,Sundaramoorthy, R.,White, M.F.
Structure and mechanism of the type I-G CRISPR effector.
Nucleic Acids Res., 50:11214-11228, 2022

PubMed Abstract: Type I CRISPR systems are the most common CRISPR type found in bacteria. They use a multisubunit effector, guided by crRNA, to detect and bind dsDNA targets, forming an R-loop and recruiting the Cas3 enzyme to facilitate target DNA destruction, thus providing immunity against mobile genetic elements. Subtypes have been classified into families A-G, with type I-G being the least well understood. Here, we report the composition, structure and function of the type I-G Cascade CRISPR effector from Thioalkalivibrio sulfidiphilus, revealing key new molecular details. The unique Csb2 subunit processes pre-crRNA, remaining bound to the 3' end of the mature crRNA, and seven Cas7 subunits form the backbone of the effector. Cas3 associates stably with the effector complex via the Cas8g subunit and is important for target DNA recognition. Structural analysis by cryo-Electron Microscopy reveals a strikingly curved backbone conformation with Cas8g spanning the belly of the structure. These biochemical and structural insights shed new light on the diversity of type I systems and open the way to applications in genome engineering.

PubMed: 36305833
DOI: 10.1093/nar/gkac925

Experimental method

ELECTRON MICROSCOPY (8 Å)