6C66

CRISPR RNA-guided surveillance complex, pre-nicking

Summary for 6C66

• Entry DOI: 10.2210/pdb6c66/pdb
• Related: 6C66
• EMDB information: 7346 7347
• Descriptor: CRISPR-associated helicase, Cas3 family, FE (III) ION, CRISPR-associated protein, Cse1 family, ... (10 entities in total)
• Functional Keywords: crispr-cas, cascade, cas3, dna binding protein, dna binding protein-dna-rna complex, dna binding protein/dna/rna
• Biological source: Thermobifida fusca (strain YX); More
• Total number of polymer chains: 15
• Total formula weight: 575035.33

Authors

Xiao, Y.,Luo, M.,Liao, M.,Ke, A. (deposition date: 2018-01-17, release date: 2018-06-27, Last modification date: 2023-11-29)

Primary citation

Xiao, Y.,Luo, M.,Dolan, A.E.,Liao, M.,Ke, A.
Structure basis for RNA-guided DNA degradation by Cascade and Cas3.
Science, 361:-, 2018

PubMed Abstract: Type I CRISPR-Cas system features a sequential target-searching and degradation process on double-stranded DNA by the RNA-guided Cascade (CRISPR associated complex for antiviral defense) complex and the nuclease-helicase fusion enzyme Cas3, respectively. Here, we present a 3.7-angstrom-resolution cryo-electron microscopy (cryo-EM) structure of the Type I-E Cascade/R-loop/Cas3 complex, poised to initiate DNA degradation. Cas3 distinguishes Cascade conformations and only captures the R-loop-forming Cascade, to avoid cleaving partially complementary targets. Its nuclease domain recruits the nontarget strand (NTS) DNA at a bulged region for the nicking of single-stranded DNA. An additional 4.7-angstrom-resolution cryo-EM structure captures the postnicking state, in which the severed NTS retracts to the helicase entrance, to be threaded for adenosine 5'-triphosphate-dependent processive degradation. These snapshots form the basis for understanding RNA-guided DNA degradation in Type I-E CRISPR-Cas systems.

PubMed: 29880725
DOI: 10.1126/science.aat0839

Experimental method

ELECTRON MICROSCOPY (3.66 Å)