P45956 · CAS2_ECOLI

Function

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) (PubMed:21255106, PubMed:24793649, PubMed:24920831).
CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). The Cas1-Cas2 complex is involved in CRISPR adaptation, the first stage of CRISPR immunity, being required for the addition/removal of CRISPR spacers at the leader end of the CRISPR locus (PubMed:24793649, PubMed:24920831, PubMed:25707795).
The Cas1-Cas2 complex introduces staggered nicks into both strands of the CRISPR array near the leader repeat and joins the 5'-ends of the repeat strands with the 3'-ends of the new spacer sequence (PubMed:24920831).
Spacer DNA integration requires supercoiled target DNA and 3'-OH ends on the inserted (spacer) DNA and probably initiates with a nucleophilic attack of the C 3'-OH end of the protospacer on the minus strand of the first repeat sequence (PubMed:25707795).
Expression of Cas1-Cas2 in a strain lacking both genes permits spacer acquisition (PubMed:24793649, PubMed:24920831).
Cas2 not seen to bind DNA alone; the Cas1-Cas2 complex preferentially binds CRISPR-locus DNA (PubMed:24793649).
Highest binding is seen to a dual forked DNA complex with 3'-overhangs and a protospacer-adjacent motif-complement specifically positioned (PubMed:26478180).
The protospacer DNA lies across a flat surface extending from 1 Cas1 dimer, across the Cas2 dimer and contacting the other Cas1 dimer; the 23 bp-long ds section of the DNA is bracketed by 1 Tyr-22 from each of the Cas1 dimers (PubMed:26478180, PubMed:26503043).
Cas1 cuts within the 3'-overhang, to generate a 33-nucleotide DNA that is probably incorporated into the CRISPR leader by a cut-and-paste mechanism (PubMed:26478180).
This subunit's probable nuclease activity is not required for spacer acquisition (PubMed:24793649).

GO annotations

AspectTerm
Molecular FunctionDNA binding
Molecular Functionendonuclease activity
Biological ProcessCRISPR-cas system
Biological Processdefense response to virus
Biological Processmaintenance of CRISPR repeat elements

Keywords

Enzyme and pathway databases

Names & Taxonomy

Protein names

  • Recommended name
    CRISPR-associated endoribonuclease Cas2
  • EC number

Gene names

    • Name
      ygbF
    • Synonyms
      cas2
    • Ordered locus names
      b2754, JW5438

Organism names

  • Taxonomic identifier
  • Strains
    • K12
    • K12 / MG1655 / ATCC 47076
    • K12 / W3110 / ATCC 27325 / DSM 5911
  • Taxonomic lineage
    Bacteria > Pseudomonadota > Gammaproteobacteria > Enterobacterales > Enterobacteriaceae > Escherichia

Accessions

  • Primary accession
    P45956
  • Secondary accessions
    • Q2MA75

Proteomes

Phenotypes & Variants

Disruption phenotype

Loss of plasmid silencing (PubMed:21255106).

Features

Showing features for mutagenesis.

TypeIDPosition(s)Description
Mutagenesis9No effect on spacer acquisition, Cas1-Cas2 complex formation or CRISPRDNA-binding by complex.
Mutagenesis10No effect on spacer acquisition.
Mutagenesis14Slight decrease in spacer acquisition.
Mutagenesis14-16No in vivspacer acquisition, significantly decreased protospacer binding.
Mutagenesis16Slight decrease in spacer acquisition.
Mutagenesis16Dramatically decreased spacer acquisition in vivo.
Mutagenesis18Very little spacer acquisition.
Mutagenesis27Slight decrease in spacer acquisition.
Mutagenesis38-40Very little in vivo spacer acquisition.
Mutagenesis65No effect on spacer acquisition.
Mutagenesis65Slight decrease in spacer acquisition, Cas1-Cas2 complex formation or CRISPRDNA-binding by complex. Loss of spacer acquisition; when associated with R-84.
Mutagenesis77No change in spacer acquisition in vivo.
Mutagenesis77-78No spacer acquisition, significantly decreased protospacer binding.
Mutagenesis78Dramatically decreased spacer acquisition in vivo.
Mutagenesis79-94Loss of spacer acquisition, no Cas1-Cas2 complex formation, loss of CRISPRDNA-binding by complex (beta6-beta7 deletion).
Mutagenesis84No effect on spacer acquisition.
Mutagenesis84Slight decrease in spacer acquisition. Loss of spacer acquisition; when associated with R-65.

PTM/Processing

Features

Showing features for chain.

TypeIDPosition(s)Description
ChainPRO_00001693121-94CRISPR-associated endoribonuclease Cas2

Proteomic databases

Expression

Induction

Repressed by H-NS (PubMed:20132443).
Activated by LeuO (PubMed:19429622).
Activated by the BaeSR two-component regulatory system, possibly due to envelope stress (PubMed:21255106).
Part of the casABCDE-ygbT-ygbF operon (PubMed:19429622).

Interaction

Subunit

Homodimer (Ref.10). Part of the Cas1-Cas2 complex (PubMed:24793649, PubMed:24920831, PubMed:25707795, PubMed:26478180, PubMed:26503043, Ref.12). Forms a hexamer with 2 Cas1 dimers sandwiching a Cas2 dimer (PubMed:24793649).
The DNA lies across a flat surface extending from 1 Cas1 dimer, across the Cas2 dimer and contacting the other Cas1 dimer. Only 1 Cas1 protein from each dimer is catalytic, the other interacts with the Cas2 dimer and possibly target DNA (PubMed:26478180, PubMed:26503043).

Binary interactions

TypeEntry 1Entry 2Number of experimentsIntact
BINARY P45956ygbT Q468968EBI-9150552, EBI-1130209

Protein-protein interaction databases

Family & Domains

Domain

Substrate DNA-binding induces large structural changes that generate a surface for DNA-binding across the Cas2 dimer and formation of an optimal catalytic site (PubMed:26478180).

Sequence similarities

Phylogenomic databases

Family and domain databases

Sequence

  • Sequence status
    Complete
  • Length
    94
  • Mass (Da)
    10,518
  • Last updated
    2000-05-30 v2
  • Checksum
    D1C159D924B477B4
MSMLVVVTENVPPRLRGRLAIWLLEVRAGVYVGDVSAKIREMIWEQIAGLAEEGNVVMAWATNTETGFEFQTFGLNRRTPVDLDGLRLVSFLPV

Keywords

Sequence databases

Nucleotide SequenceProtein SequenceMolecule TypeStatus
M27059
EMBL· GenBank· DDBJ
-Unassigned DNA No translation available.
U29579
EMBL· GenBank· DDBJ
AAA69264.1
EMBL· GenBank· DDBJ
Genomic DNA
U00096
EMBL· GenBank· DDBJ
AAC75796.2
EMBL· GenBank· DDBJ
Genomic DNA
AP009048
EMBL· GenBank· DDBJ
BAE76831.1
EMBL· GenBank· DDBJ
Genomic DNA

Genome annotation databases

Similar Proteins

Disclaimer

Any medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care. Our staff consists of biologists and biochemists that are not trained to give medical advice.
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