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-Structure paper
Title | Structure basis for RNA-guided DNA degradation by Cascade and Cas3. |
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Journal, issue, pages | Science, Vol. 361, Issue 6397, Year 2018 |
Publish date | Jul 6, 2018 |
Authors | Yibei Xiao / Min Luo / Adam E Dolan / Maofu Liao / Ailong Ke / |
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 ...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. |
External links | Science / PubMed:29880725 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.66 Å |
Structure data | |
Chemicals | ChemComp-FE: |
Source |
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Keywords | DNA BINDING PROTEIN/DNA/RNA / CRISPR-Cas / Cascade / Cas3 / DNA BINDING PROTEIN / DNA BINDING PROTEIN-DNA-RNA complex |