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2  structures 97  species 0  interactions 119  sequences 3  architectures

Family: Cas_APE2256 (PF09651)

Summary: CRISPR-associated protein (Cas_APE2256)

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The Pfam group coordinates the annotation of Pfam families in Wikipedia, but we have not yet assigned a Wikipedia article to this family. If you think that a particular Wikipedia article provides good annotation, please let us know.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

CRISPR-associated protein (Cas_APE2256) Provide feedback

This entry represents a conserved region of about 150 amino acids found in at least five archaeal and three bacterial species. These species all contain CRISPRs (Clustered Regularly Interspaced Short Palindromic Repeats). In six of eight species, the protein is encoded the vicinity of a CRISPR/Cas locus.

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR013442

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are a family of DNA direct repeats separated by regularly sized non-repetitive spacer sequences that are found in most bacterial and archaeal genomes [PUBMED:17442114]. CRISPRs appear to provide acquired resistance against bacteriophages, possibly acting with an RNA interference-like mechanism to inhibit gene functions of invasive DNA elements [PUBMED:17379808, PUBMED:16545108]. Differences in the number and type of spacers between CRISPR repeats correlate with phage sensitivity. It is thought that following phage infection, bacteria integrate new spacers derived from phage genomic sequences, and that the removal or addition of particular spacers modifies the phage-resistance phenotype of the cell. Therefore, the specificity of CRISPRs may be determined by spacer-phage sequence similarity.

In addition, there are many protein families known as CRISPR-associated sequences (Cas), which are encoded in the vicinity of CRISPR loci [PUBMED:16292354]. CRISPR/cas gene regions can be quite large, with up to 20 different, tandem-arranged cas genes next to a CRISPR cluster or filling the region between two repeat clusters. Cas genes and CRISPRs are found on mobile genetic elements such as plasmids, and have undergone extensive horizontal transfer. Cas proteins are thought to be involved in the propagation and functioning of CRISPRs. Some Cas proteins show similarity to helicases and repair proteins, although the functions of most are unknown. Cas families can be divided into subtypes according to operon organisation and phylogeny.

This entry represents a conserved region of about 150 amino acids found in a family of Cas proteins in at least five archaeal and three bacterial species. In six of eight species, the protein is encoded the vicinity of a CRISPR/Cas locus.

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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Alignments

We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the NCBI sequence database, and our metagenomics sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

  Seed
(28)
Full
(119)
Representative proteomes NCBI
(125)
Meta
(1)
RP15
(32)
RP35
(43)
RP55
(49)
RP75
(56)
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1Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: ✓ available, x not generated, not available.

Format an alignment

  Seed
(28)
Full
(119)
Representative proteomes NCBI
(125)
Meta
(1)
RP15
(32)
RP35
(43)
RP55
(49)
RP75
(56)
Alignment:
Format:
Order:
Sequence:
Gaps:
Download/view:

Download options

We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

  Seed
(28)
Full
(119)
Representative proteomes NCBI
(125)
Meta
(1)
RP15
(32)
RP35
(43)
RP55
(49)
RP75
(56)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   Download   Download   Download   Download   Download   Download   Download  

You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

External links

MyHits provides a collection of tools to handle multiple sequence alignments. For example, one can refine a seed alignment (sequence addition or removal, re-alignment or manual edition) and then search databases for remote homologs using HMMER3.

HMM logo

HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...

Trees

This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

Note: You can also download the data file for the tree.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: TIGRFAMs
Previous IDs: none
Type: Family
Author: TIGRFAMs, Coggill P
Number in seed: 28
Number in full: 119
Average length of the domain: 135.30 aa
Average identity of full alignment: 23 %
Average coverage of the sequence by the domain: 39.62 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 24.8 24.8
Trusted cut-off 25.0 25.1
Noise cut-off 24.2 24.0
Model length: 136
Family (HMM) version: 5
Download: download the raw HMM for this family

Species distribution

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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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Structures

For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Cas_APE2256 domain has been found. There are 2 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.

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