6GTD image
Entry Detail
PDB ID:
6GTD
EMDB ID:
Keywords:
Title:
Transient state structure of CRISPR-Cpf1 (Cas12a) I2 conformation
Biological Source:
PDB Version:
Deposition Date:
2018-06-18
Release Date:
2018-12-19
Method Details:
Experimental Method:
Resolution:
4.24 Å
Aggregation State:
PARTICLE
Reconstruction Method:
SINGLE PARTICLE
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:CRISPR-associated endonuclease Cas12a
Chain IDs:A
Chain Length:1329
Number of Molecules:1
Biological Source:Francisella tularensis subsp. novicida (strain U112)
Polymer Type:polyribonucleotide
Description:RNA (28-MER)
Chain IDs:B
Chain Length:43
Number of Molecules:1
Biological Source:Francisella tularensis subsp. novicida U112
Polymer Type:polydeoxyribonucleotide
Description:DNA (5'-D(P*TP*GP*AP*CP*TP*TP*CP*TP*CP*TP*AP*AP*CP*AP*AP*GP*CP*TP*CP*G)-3')
Chain IDs:C
Chain Length:55
Number of Molecules:1
Biological Source:Francisella tularensis subsp. novicida U112
Polymer Type:polydeoxyribonucleotide
Description:DNA (5'-D(P*CP*GP*AP*GP*CP*TP*CP*GP*TP*TP*AP*GP*AP*GP*AP*AP*GP*T)-3')
Chain IDs:D
Chain Length:55
Number of Molecules:1
Biological Source:Francisella tularensis subsp. novicida U112
Ligand Molecules
Primary Citation
Conformational Activation Promotes CRISPR-Cas12a Catalysis and Resetting of the Endonuclease Activity.
Cell 175 1856 1871.e21 (2018)
PMID: 30503205 DOI: 10.1016/j.cell.2018.10.045

Abstact

Cas12a, also known as Cpf1, is a type V-A CRISPR-Cas RNA-guided endonuclease that is used for genome editing based on its ability to generate specific dsDNA breaks. Here, we show cryo-EM structures of intermediates of the cleavage reaction, thus visualizing three protein regions that sense the crRNA-DNA hybrid assembly triggering the catalytic activation of Cas12a. Single-molecule FRET provides the thermodynamics and kinetics of the conformational activation leading to phosphodiester bond hydrolysis. These findings illustrate why Cas12a cuts its target DNA and unleashes unspecific cleavage activity, degrading ssDNA molecules after activation. In addition, we show that other crRNAs are able to displace the R-loop inside the protein after target DNA cleavage, terminating indiscriminate ssDNA degradation. We propose a model whereby the conformational activation of the enzyme results in indiscriminate ssDNA cleavage. The displacement of the R-loop by a new crRNA molecule will reset Cas12a specificity, targeting new DNAs.

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Primary Citation of related structures