CRISPR-associated endonuclease Cas12a - A0Q7Q2 (CS12A_FRATN)


Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for A0Q7Q2: 10
CRISPR (clustered regularly interspaced short palindromic repeat), is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). Has endonuclease activity on pre-crRNA and dsDNA, using different active sites. A single-RNA guided endonuclease that is also capable of guiding crRNA processing; correct processing of pre-crRNA requires only this protein and the CRISPR locus (PubMed:26422227, PubMed:27096362). pre-crRNA processing proceeds by an intramolecular nucleophilic attack on the scissile phosphate by the 2'-OH of the upstream ribonucleotide, the divalent cation (which is bound by the crRNA) is probably required for ordering the crRNA pseudoknot and/or increasing RNA binding (PubMed:28431230). RNA mutagenesis studies show pre-crRNA cleavage is highly sequence- and structure-specific (PubMed:27096362). Forms a complex with crRNA and complementary dsDNA, where the crRNA displaces the non-target DNA strand and directs endonucleolytic cleavage of both strands of the DNA (PubMed:26422227, PubMed:27096362, PubMed:28431230). Cleavage results in staggered 5-base 5' overhangs 14-18 and 21-23 bases downstream of the PAM (protospacer adjacent motif) on the non-target and target strands respectively (PubMed:26422227, PubMed:28431230, PubMed:28562584). Both target and non-target strand DNA are probably independently cleaved in the same active site (PubMed:28431230, PubMed:28562584). When this protein is expressed in E.coli it prevents plasmids homologous to the first CRISPR spacer from transforming, formally showing it is responsible for plasmid immunity (PubMed:26422227). UniProt
Catalytic Activity
RNA = a 5'-hydroxy-ribonucleotide + n nucleoside-2',3'-cyclophosphates. UniProt
Pathway Maps
      ESCHER  BiGG
Subunit Structure
Might be a homodimer (PubMed:26422227). Might be a monomer (PubMed:27096362, PubMed:28431230). UniProt
Has bilobed structure, with the REC lobe (residues 25-591) connected to the NUC lobe (662-1300) by a discontinuous wedge domain (PubMed:28431230, PubMed:28562584). The REC lobe binds the (pre-)crRNA and the crRNA-target DNA heteroduplex (PubMed:28431230, PubMed:28562584). The heteroduplex as well as part of the DNA downstream of the heteroduplex is protected in the central cavity formed by the NUC and REC lobes, which also positions target and non-target DNA for cleavage after domain rearrangement (PubMed:28431230, PubMed:28562584). The LKL region (residues 662 to 679) inserts into target dsDNA initiating its disruption to allow crRNA hybridization, is also involved in determining the non-target strand cleavage site (PubMed:28562584). A 'septum' formed by resdiues 197-204 and 1061-1070 separates the 2 DNA strands, preventing their reannealing, this region also influences the non-target cleavage site (PubMed:28562584). UniProt
  • Other Gene names: cas12a, cpf1, FTN_1397
This protein in other organisms (by gene name):
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Data in green originates from UniProtKB  
Variation data (sourced from UniProt) shows non-genetic variation from the ExPASy   and dbSNP   websites.
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
Data in purple originates from Phosphosite  .
Data in orange originates from the SCOP   (version 1.75) and SCOPe   (version 2.04) classifications.
Data in grey has been calculated using BioJava  . Protein disorder predictions are based on JRONN (Troshin, P. and Barton, G. J. unpublished), a Java implementation of RONN  
  • Red: potentially disorderd region
  • Blue: probably ordered region.
Hydropathy has been calculated using a sliding window of 15 residues and summing up scores from standard hydrophobicity tables.
  • Red: hydrophobic
  • Blue: hydrophilic.
Data in lilac represent the genomic exon structure projected onto the UniProt sequence.
Data in blue originates from PDB
  • Secstruc: Secondary structure projected from representative PDB entries onto the UniProt sequence.
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Validation Track

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Data in red indicates combined ranges of Homology Models from the SWISS-MODEL Repository  
The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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