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CRISPR-associated endonuclease Cas9/Csn1 - Q99ZW2 (CAS9_STRP1)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

Number of PDB entries for Q99ZW2: 6
 
Function
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 spacers, sequences complementary to antecedent mobile elements, and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). In type II CRISPR systems correct processing of pre-crRNA requires a trans-encoded small RNA (tracrRNA), endogenous ribonuclease 3 (rnc) and this protein. The tracrRNA serves as a guide for ribonuclease 3-aided processing of pre-crRNA; Cas9 only stabilizes the pre-crRNA:tracrRNA interaction and has no catalytic function in RNA processing (PubMed:24270795). Subsequently Cas9/crRNA/tracrRNA endonucleolytically cleaves linear or circular dsDNA target complementary to the spacer; Cas9 is inactive in the absence of the 2 guide RNAs (gRNA). The target strand not complementary to crRNA is first cut endonucleolytically, then trimmed 3'-5' exonucleolytically. DNA-binding requires protein and both gRNAs, as does nuclease activity. Cas9 recognizes the protospacer adjacent motif (PAM) in the CRISPR repeat sequences to help distinguish self versus nonself, as targets within the bacterial CRISPR locus do not have PAMs. DNA strand separation and heteroduplex formation starts at PAM sites; PAM recognition is required for catalytic activity. Confers immunity against a plasmid with homology to the appropriate CRISPR spacer sequences (CRISPR interference). (data source: UniProt  )
Subunit structure
Monomer. Binds crRNA and tracrRNA. (data source: UniProt  )
Domain
The PAM-interacting domain (PI domain, approximately residues 1099-1368) recognizes the PAM motif; swapping the PI domain of this enzyme with that from S.thermophilus St3Cas9 (AC Q03JI6) prevents cleavage of DNA with the endogenous PAM site (5'-NGG-3') but confers the ability to cleave DNA with the PAM site specific for St3 CRISPRs (PubMed:24529477). (data source: UniProt  )
UniProtKB:
Species: 
Gene names: cas9 csn1 SPy_1046
Length:
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Data origin/color codes
The vertical color bar on the left side indicates data provenance.
Data in green originates from UniProtKB  
Data in yellow originates from Pfam  , by interacting with the HMMER3 web site  
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.
Data in red indicates combined ranges of Homology Models from SBKB   and the Protein Model Portal  

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).