PF01881: Cas_Cas6_C

Grounding

PF01881: CRISPR associated protein Cas6, C-terminal
IPR049435: integrated entry for CRISPR associated protein Cas6, C-terminal

Source 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 [InterPro reference PUB00020781]. 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 [InterPro reference PUB00106643]. Cas5 contains an endonuclease motif, whose inactivation leads to loss of resistance, even in the presence of phage-derived spacers [InterPro reference PUB00109113]. In Type I and III CRISPR/Cas systems, the Cas6 family of endoribonucleases generates functional CRISPR-derived RNAs by site-specific cleavage of repeat sequences in precursor transcripts. The structure of Cas6 [InterPro reference PUB00098896] showed it adopts a tandem ferredoxin/RRM fold. This entry represents the C-terminal domain.

Evidence and references

• InterPro entry and its literature references. PUB identifiers are internal InterPro references, not PubMed identifiers. Unresolved citations link to the originating entry.
• Frozen description source: InterPro/Pfam API

Source descriptions and links are provenance, not independent functional validation.

Evidence counts: not scored.

Curated functional assertions

No curated functional assertions supplied.

Protein sequence examples

6 verified sequence examples. FASTA

Pfam membership is not functional evidence. Whole-protein sequences do not establish domain boundaries. A coverage gap here is not absence from UniProt.

Sequences and metadata: UniProt Consortium, CC BY 4.0.

Domain matches

No residue-level domain match evidence is available in this build. Structure and AlphaFold counters do not supply coordinates or establish function.

Snapshot counters

proteins

1,831

matches

1,832

proteomes

1,415

taxa

2,926

structures

7

alphafold models

1,415

domain architectures

4

Classification basis

pfam previous unknown name

No scoring reasons supplied.

Related Mech records

This family joined the worklist after the frozen cross-Mech scan, so other Mechs were not searched for it. Missing links here are not evidence that other Mechs lack it; rows shown come from mentions of a former DUF/UPF name.

No cross-Mech examples are present in the supplied snapshot.

Curation history and reviews

No retained curation events supplied.

No retained review supplied.

Record source

data/families/PF01881.yaml
Family YAML in this build

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