Please note: this site relies heavily on the use of javascript. Without a javascript-enabled browser, this site will not function correctly. Please enable javascript and reload the page, or switch to a different browser.
0  structures 37  species 0  interactions 39  sequences 1  architecture

Family: Cas6 (PF09559)

Summary: Cas6 Crispr

Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.

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.

Cas6 Crispr Provide feedback

The Cas6 Crispr family of proteins averaging 140 residues are characterised by having a GhGxxxxxGhG motif, where h indicates a hydrophobic residue, at the C-terminus [1]. The CRISPR-Cas system is possibly a mechanism of defence against invading pathogens and plasmids that functions analogously to the RNA interference (RNAi) systems in eukaryotes [2].

Literature references

  1. Haft DH, Selengut J, Mongodin EF, Nelson KE; , PLoS Comput Biol. 2005;1:e60.: A guild of 45 CRISPR-associated (Cas) protein families and multiple CRISPR/Cas subtypes exist in prokaryotic genomes. PUBMED:16292354 EPMC:16292354

  2. Makarova KS, Grishin NV, Shabalina SA, Wolf YI, Koonin EV; , Biol Direct. 2006;1:7.: A putative RNA-interference-based immune system in prokaryotes: computational analysis of the predicted enzymatic machinery, functional analogies with eukaryotic RNAi, and hypothetical mechanisms of action. PUBMED:16545108 EPMC:16545108


This tab holds annotation information from the InterPro database.

InterPro entry IPR014174

The CRISPR-Cas system is a prokaryotic defense mechanism against foreign genetic elements. The key elements of this defense system are the Cas proteins and the CRISPR RNA.

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 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).

The defense reaction is divided into three stages. In the adaptation stage, the invader DNA is cleaved, and a piece of it is selected to be integrated as a new spacer into the CRISPR locus, where it is stored as an identity tag for future attacks by this invader. During the second stage (the expression stage), the CRISPR RNA (pre-crRNA) is transcribed and subsequently processed into the mature crRNAs. In the third stage (the interference stage), Cas proteins, together with crRNAs, identify and degrade the invader [PUBMED:17379808, PUBMED:16545108, PUBMED:21699496].

The CRISPR-Cas systems have been sorted into three major classes. In CRISPR-Cas types I and III, the mature crRNA is generally generated by a member of the Cas6 protein family. Whereas in system III the Cas6 protein acts alone, in some class I systems it is part of a complex of Cas proteins known as Cascade (CRISPR-associated complex for antiviral defense). The Cas6 protein is necessary for crRNA production whereas the additional Cas proteins that form the Cascade complex are needed for crRNA stability [PUBMED:24459147].

Members of this entry resemble the Cas6 proteins described by INTERPRO in having a C-terminal motif GXGXXXXXGXG, where the single X of each GXG is hydrophobic and the spacer XXXXX has at least one Lys or Arg. Examples are found in cas gene operons of CRISPR regions in Anabaena variabilis (strain ATCC 29413/PCC 7937), Leptospira interrogans, Gemmata obscuriglobus UQM 2246, and twice in Myxococcus xanthus (strain DK 1622). Oddly, an orphan member is found in Thiobacillus denitrificans (strain ATCC 25259), whose genome does not seem to contain other evidence of CRISPR repeats or cas genes.

Domain organisation

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

Loading domain graphics...

Pfam Clan

This family is a member of clan RAMPS-Cas5-like (CL0362), which has the following description:

This group of families is one of several protein families that are always found associated with prokaryotic CRISPRs, themselves a family of clustered regularly interspaced short palindromic repeats, DNA repeats found in nearly half of all bacterial and archaeal genomes. These DNA repeat regions have a remarkably regular structure: unique sequences of constant size, called spacers, sit between each pair of repeats [1]. It has been shown that the CRISPRs are virus-derived sequences acquired by the host to enable them to resist viral infection. The Cas proteins from the host use the CRISPRs to mediate an antiviral response. After transcription of the CRISPR, a complex of Cas proteins termed Cascade cleaves a CRISPR RNA precursor in each repeat and retains the cleavage products containing the virus-derived sequence. Assisted by the helicase Cas3, these mature CRISPR RNAs then serve as small guide RNAs that enable Cascade to interfere with virus proliferation [2]. Cas5 contains an endonuclease motif, whose inactivation leads to loss of resistance, even in the presence of phage-derived spacers [3].

The clan contains the following 7 members:

Cas6 Cas_Cas5d Cas_Cas6 Cas_Cmr3 CRISPR_assoc DUF2276 RAMPs

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 (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets, the UniProtKB sequence database, the NCBI sequence database, and our metagenomics sequence database. More...

View options

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
(35)
Full
(39)
Representative proteomes UniProt
(130)
NCBI
(183)
Meta
(26)
RP15
(10)
RP35
(36)
RP55
(44)
RP75
(51)
Jalview View  View  View  View  View  View  View  View  View 
HTML View  View               
PP/heatmap 1 View               

1Cannot generate PP/Heatmap alignments for seeds; no PP data available

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

Format an alignment

  Seed
(35)
Full
(39)
Representative proteomes UniProt
(130)
NCBI
(183)
Meta
(26)
RP15
(10)
RP35
(36)
RP55
(44)
RP75
(51)
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
(35)
Full
(39)
Representative proteomes UniProt
(130)
NCBI
(183)
Meta
(26)
RP15
(10)
RP35
(36)
RP55
(44)
RP75
(51)
Raw Stockholm Download   Download   Download   Download   Download   Download   Download   Download   Download  
Gzipped Download   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.

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: 35
Number in full: 39
Average length of the domain: 198.20 aa
Average identity of full alignment: 33 %
Average coverage of the sequence by the domain: 90.91 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 11927849 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 26.6 26.6
Trusted cut-off 117.7 117.5
Noise cut-off 26.5 26.5
Model length: 191
Family (HMM) version: 7
Download: download the raw HMM for this family

Species distribution

Sunburst controls

Hide

Weight segments by...


Change the size of the sunburst

Small
Large

Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence

Selections

Align selected sequences to HMM

Generate a FASTA-format file

Clear selection

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...

Loading sunburst data...

Tree controls

Hide

The tree shows the occurrence of this domain across different species. More...

Loading...

Please note: for large trees this can take some time. While the tree is loading, you can safely switch away from this tab but if you browse away from the family page entirely, the tree will not be loaded.